Marks Daily Apple
Serving up health and fitness insights (daily, of course) with a side of irreverence.
15 Mar

Why Fast? Part One – Weight Loss

“When a person has nothing to eat, fasting is the smartest thing he could do.” – Herman Hesse, Siddhartha.

I like that quote. It’s making (non-caloric) lemonade out of lemons, and for all the transcendental insights contained in Hesse’s book, this line strikes me as a really cool, no-nonsense way to make the best out of a bad situation. No doubt about that. But how useful is it, really, to today’s readers? Very few of us ever have “nothing to eat.” On the contrary, food is ever at our beck and call, with very little effort required to obtain it. Actually, that’s not completely true. Processed junk and fast food is readily available, while the good stuff – fresh meat and veggies, actual, you know, food – requires prep work, cooking, time, and the doing of dishes. But the main point stands: we rarely go without.

That doesn’t mean the quote is useless. In fact, with a few slight modifications, it becomes extremely effective weight loss advice. Check out my version:

“When a person has had too much to eat, fasting is the smartest thing he could do.” – Mark Sisson, Mark’s Daily Apple.

If that sounds harsh or even unrealistic, consider the story of the Scotsman. Back in 1965, an obese Scotsman of 27 years and 456 pounds came to the Department of Medicine in Dundee, Scotland, with a problem. He needed to lose weight. A (1/8 of a) ton of it. The doctors suggested maybe not eating for a few days could help. It was just an offhand recommendation, but our Scotsman (known only as “AB”) really took to it. He stayed at the hospital for several days, taking only water and vitamin pills while undergoing observation to ensure nothing went wrong. When his time was up, he continued the fast back at home, returning to the hospital only for regular monitoring. After a week, he was down five pounds and feeling good. His vitals checked out, blood pressure was normal, and though he had lower blood sugar than most men, he didn’t seem particularly impaired by it. The experiment continued… for 382 days.

Yes, AB fasted for 382 days, drinking only water and taking vitamin, potassium, and sodium supplements. All told, he lost 276 pounds, reaching his target weight of 180 pounds and maintaining the bulk of his weight loss. Over the five following years of observation, AB regained just sixteen pounds, putting him in excellent, but underpopulated territory (at least 80% of dieters eventually regain all the lost weight). Other doctors paid attention. Maybe it was the fact that it was the 60s, and all sorts of crazy stuff was going on – rebellion in the air, good music being made, a war in Vietnam, Ken Kesey and his Merry Pranksters blazing across the U.S. in a beat-up school bus, spreading the good weird word, Kevin Arnold and a young Marilyn Manson coming of age in Anytown, USA – but for whatever reason, placing obese patients on extended and short-term fasts became relatively common practice.

But could this work for the average person looking to lose weight without submitting to constant medical observation?

Absolutely. Study after study shows that whatever you want to call the protocol – intermittent fasting, fasting, alternate day fasting, or alternate day caloric restriction – it works very well for weight loss. A few recent ones:

So, yes: it works. But does fasting work solely through caloric restriction, or is it doing something special?

That’s the real question. There’s no question that fasting causes weight loss through caloric restriction. Obviously, when you don’t eat anything, your body turns to its own stored energy reserves, reserves that take up physical space and have mass. Depletion of those energy stores reduces mass and thus weight. Total and absolute caloric restriction. That’s elementary stuff and the studies from the 1960s show that.

To dig a bit deeper, let’s look at how weight loss occurs during a fast. I’ll stick to research involving humans only (sorry, rodent personal trainers).

Secretion of growth hormone, one of the premier fat burning hormones, increases during a fast. In a five-day fasting protocol, men experienced increased GH secretion on day one and day five (the only two days where GH was measured). A later study showed that during two-day fasting sessions, growth hormone secretions increased in both frequency and intensity in men. They experienced more frequent GH bursts and each burst secreted a higher mass of GH. A more recent study found that 24-hour fasts increased GH by 1300% in women and almost 2000% in men.

Fasting decreases fasting insulin levels. The presence of insulin inhibits lipolysis, the release of stored triglycerides (body fat). Without lipolysis actually releasing stored body fat, it’s rather difficult to, well, burn that body fat for energy. During a fast, fasting insulin decreases and lipolysis increases. This insulin-blunting aspect of fasting quite literally allows the fast to be successful, because without the ability to access stored body fat for energy, making it through a period of zero caloric intake will be nigh impossible.

Fasting improves insulin sensitivity. 20-hour fasts were enough to improve insulin sensitivity in men.

Fasting increases the catecholamines, both adrenaline (epinephrine) and noradrenaline (norepinephrine). Both catecholamines increase resting energy expenditure during a fast, and guess where your fasting body finds the energy to expend? From body fat. Catecholamines activate hormone sensitive lipase present in adipose tissue, spurring the release of said fat. This makes intuitive sense, doesn’t it? If you’re hungry in the wild, you need to hunt (or gather, or fish, or somehow procure food) and you need energy to do it. The catecholamines help provide some of that energy while burning fat in the process.

Hmm, notice anything? All those mechanisms dealt with fat burning specifically. While there may be some weirdo out there who’s interested in reducing bone mineral density and muscle mass while maintaining fat tissue, I would wager that what most people mean by “weight loss” is “fat mass loss.” From the stuff I just linked, it looks like fasting burns fat, rather than just weight. But what about Conventional Wisdom which claims that fasting increases muscle wasting – maybe because your body will totally recognize the lethal nature of all that arterycloggingsaturated animal fat and choose to break down muscle instead? Is it true?

Let’s go to the research:

In one study, normal weight subjects ate just once a day without reducing overall caloric intake. Weight didn’t change, which isn’t really surprising, but body composition did change – and for the better. Body fat decreased and lean weight increased (in addition to a bunch of other beneficial changes) without an overall reduction in calories.

recent review of the relevant literature found that while fasting and caloric restriction are “equally as effective in decreasing body weight and fat mass,” fasting is “more effective for the retention of lean mass.”

Conventional Wisdom strikes out again.

In closing…

It appears that fasting “works” in several different ways:

1. It decreases caloric intake. In order to lose weight, you need a caloric deficit. That really isn’t in contention here, folks.

2. It increases fat oxidation while sparing lean mass. Since what we’re trying to do is lose fat (rather than just “weight”), the fact that fasting increases hormones that preferentially burn fat and decreases hormones that inhibit fat burning is extremely desirable.

3. It improves adherence. In most of the studies surveyed, participants found fasting to be an extremely tolerable way to diet, especially when compared to outright caloric restriction. Even AB, the fasting Scotsman, reported very little difficulty throughout his 382 day fast. If fasting is easier for you than trying to laboriously count calories, fasting is going to be the more effective weight – er, fat – loss method.

All in all, fasting is an effective way to lose body fat. It’s not the only way, and it isn’t “required” for Primal weight loss, but many in the community have found it to be very helpful and the literature backs them up. If you’re looking to jumpstart your fat loss, fasting may be just the ticket. To get some ideas, be sure to check out my post on various fasting methods.

In subsequent installments, I’ll highlight some of the other benefits of fasting. There are a ton, and new research is being released all the time, so I expect I’ll have a lot to discuss. Until then, I’d like to hear about your experiences with fasting for fat loss. Has it worked? Has it failed you? Let us know in the comment section!

Thanks for reading, everyone!

Here’s the entire series for easy reference:

Why Fast? Part One – Weight Loss

Why Fast? Part Two – Cancer

Why Fast? Part Three – Longevity

Why Fast? Part Four – Brain Health

Why Fast? Part Five – Exercise

Why Fast? Part Six – Choosing a Method

Why Fast? Part Seven – Q&A

Dear Mark: Women and Intermittent Fasting

You want comments? We got comments:

Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

  1. Very interesting article, especially since I am trying to lose some weight. It seemed to me that I read somewhere that you told people not to fast until they had their weight under control, but obviously I must have that wrong.

    I personally have found that fasting happens almost effortlessly once you start eating Primal. I often have coffee for breakfast and then start getting hungry and notice I’ve worked right through lunch, and since it’s usually about 4 or 5, might as well wait and have an early supper at 6.

    Haven’t tried fasts of any longer than that yet, but since it seems to work so well for weight loss I’m certainly thinking about it now.

    Joanna wrote on March 15th, 2012
    • Good observation. It’s very easy to go from Primal/Paleo to fasting because both rely on lipolysis to fuel the body. With these fat-burning enzymes already up-regulated, going from lipolysis while eating to lipolysis while fasting is seamless.

      You can imagine how many people eating a SAD (standard American diet) might try fasting and have a terrible experience because their body just does not have enzymes needed for lipolysis in the fasted state because their bodies have up-regulated enzymes to run on glucose (sugar fixes) and not fat.

      Matthew Caton wrote on March 15th, 2012
      • There is another concern for fasting among those who aren’t primal/paleo. Sympathetic tone (aka fat burning hormone influencers) goes down with fasting. This happens at a quicker rate in those without experience missing meals.

        Because of this decrease in sympathetic tone, people may feel more lethargic than just their altered brain fuel mix may lead to. And if you try to buzz yourself with some coffee to increase sympathetic tone, lightheadness may crumple you!

        Not to mention that SAD dieters are more likely to eat things that contain artificial sweeteners, which for some may act as excitotoxins in the brain and screw up the mental picture even more.

        Not to mention that

        Kamal Patel wrote on March 15th, 2012
        • very astute observation, sir.

          luckybastard wrote on March 16th, 2012
      • I was wondering about how fasting went against common wisdom and studies that showed how muscle and bone wasting happened faster than fat loss.

        I’m also wondering if the faster muscle loss was for people who used their brains more than their bodies. Doesn’t the brain need fat, while the other systems can use any fuel, making the fat the most valuable resource to keep the brain going?

        Wild speculation on my part, but worth looking into further.

        Kelekona wrote on March 15th, 2012
        • Actualy, the brain relies purely on glucose for energy. Glucose can be synthesized by protein intake (during fasting muscle catabolism is used for this)

          Lojasmo wrote on March 15th, 2012
        • Only a fraction of the brain’s cells require glucose. I think I have read that it’s around 20%. The long, thin nerve cells in the brain have sections that don’t have mitochondria, so they need glucose for fuel.

          Todd wrote on March 15th, 2012
        • The brain can run on a mix of ketones and glucose. Up to 60% of the brain’s function can be supported by ketone bodies, the product of lipolysis alone; the remaining 40% requires glucose.

          jake3_14 wrote on March 15th, 2012
        • Lojasmo: Wrong. Just like the rest of your body, the brain runs on glucose ONLY IF YOU FEED IT GLUCOSE from carbs. If you cut carbs completely out of the diet, which has been done MANY times for up to a year or more with NO negative effects, your brain runs just fine on protein and fats. The most famous of these experiments was done in 1930 by Vilhjalmur Stefansson. Click on reference #12 to go to the original published paper here:

          “Once again, the “experts” have misled us. First, they told us that our brain wants to run exclusively on sugar (glucose) and that sugar is its preferred fuel. This is absolutely incorrect. Your brain wants to run on ketones produced from burning your own bodyfat, NOT sugar. When carbohydrates are minimized, the brain naturally obtains all the energy it needs from running on your own bodyfat. It is only when overdosiing on carbs that this mechanism is short-circuited.”

          “Surprise #6 — We are told that ketosis will cannibalize our muscle tissue. Medical Fact: After just 3-5 days of fasting, our body requires only
          1/3 the amount of glucose it has been forced to tolerate during “the great
          carbohydrate eating experiment” — we could eat less than 1/3 of a bagel a
          day and maintain superb health. The brain and nervous system start
          to use ketones, because they finally get them.”

          And From Richard Feinman:
          “Under conditions of starvation or carbohydrate restriction, acetyl-CoA can be effectively transported from the liver in the form of ketone bodies. Ketone bodies, then, are a source of acetyl-CoA that can be used by brain and CNS. Red blood cells are still dependent on glucose but the brain’s demand for glucose is reduced by the availability of ketone bodies.”

          cancerclasses wrote on March 15th, 2012
        • Your brain does need a little glucose but you don’t need to ingest that. The liver makes just enough glucose out of protein to keep the brain happy (gluconeogenisis). Ketones take care of the rest of the brain’s needs.

          Frankie wrote on March 15th, 2012
      • Hi can I fast for 3days straight and then eat? At what point will I screw up my metabolism? I don’t want that to happen! What fruits must I avoid?

        Elenor wrote on March 19th, 2012
    • No, don’t believe any of the things Mark says about fasting and weight loss. It is HORSESHIT HE PULLS OUT OF HIS ASS AND MADE-UP STUDIES THAT ARE CONTRADICTED BY OTHER STUDIES AND THE MEDICAL ESTABLISHMENT. Eventually, people will get hungry and feel the need to eat–a basic biological function–and trotting out anecdotes like the Scotsman in 1965 are scientifically worthless. Besides, how is it possible to get nutrients without eating REAL food, since vitamins have not been tested by the FDA or anyone else for proff that they really do get aabsorbed and digested?

      Jeremy wrote on April 20th, 2012
      • Jeremy, no need to be disrespectful, if you don’t like what you read, go elsewhere.

        Alvaro wrote on April 25th, 2012
      • The FDA is part of the problem with todays diet!

        Jim wrote on April 25th, 2012

          MVALITON wrote on November 14th, 2014
      • You seem like you have just enough knowledge to get yourself into arguments, but not quite enough to win them.

        Thor wrote on June 15th, 2012
        • An answer from an expert! Thanks for cotnribtinug.

          Irais wrote on August 13th, 2012
      • Hi Jeremy, I didn’t believe that vitamins were approved by the FDA either, until a pharmacist recommended taking a prescription vitamin called prenate essential or prenate elite because their vitamin c, folate etc content is higher. These vitamins are FDA approved which must mean they aren’t a waste of money. They are just more expensive. I believe prenate essential is over 100$ without insurance.I pay 50$ each month for the vitamins, because my insurance, anthem/ blue cross, pays the rest. My co-pay for meds and doctors is 30 percent, so maybe the vitamins are more expensive.
        I don’t know if men can take prenate elite or prenate essential. I would like to find out if there are prescription vitamins which are not prenatal. I keep hearing that anything that’s not fda approved is questionable…which is scary.

        Lauren wrote on October 9th, 2012
      • If interested, take a moment to look up “Features of a successful therapeutic fast of 382 days’ duration” by W. K. STEWART, M.D., F.R.C.P.E., M.R.C.P. Lond., and LAURA W. FLEMING
        B.Sc., published in Postgraduate Medical Journal (March 1973) 49, 203-209. The Abstract of this scientific article written by the doctors of the above mentioned experiment reads: Summary. A 27-year-old male patient fasted under supervision for 382 days and has subsequently maintained his normal weight. Blood glucose concentrations around
        30 mg/100 ml were recorded consistently during the last 8 months, although the patient was ambulant and attending as an out-patient. Responses to glucose and tolbutamide tolerance tests remained normal. The hyperglycaemic response to glucagon was reduced and
        latterly absent, but promptly returned to normal during carbohydrate refeeding. After an initial decrease was corrected, plasma potassium levels remained normal without supplementation. A temporary period of
        hypercalcaemia occurred towards the end of the fast. Decreased plasma magnesium concentrations were a consistent feature from the first month onwards. After 100 days of fasting there was a marked and persistent
        increase in the excretion of urinary cations and inorganic phosphate, which until then had been minimal. These increases may be due to dissolution of excessive soft tissue and skeletal mass. Prolonged fasting in this patient had no ill-effects.”

        Terri wrote on May 26th, 2013
      • After three days you are no longer hungry. Hunger comes back only when its critical to eat. I fasted for 90 days on just water. It was really easy. I walked 5 miles a day and worked in the garden. I only lost 60 pounds while most people would lose 90. I was 179 and ended up 119. I went up to 135 and kept that weight for four years. Stopped exercising and it all came back. Easiest way to lose weight that there is if you have the time to be off work. I have done several short fasts since (around 21 days) and the hunger always completely disappears after three days. No matter what I do 15 pounds always comes back fast.

        Susan wrote on October 13th, 2013
      • This idea is actually incorrect. The feeling of hunger quickly goes away if ignored because it s based heavily on daily routine. If you eat very early in the morning your body will want to eat then because it has become accustomed to doing so.

        Parker wrote on December 3rd, 2013
    • Eating Primal has removed the need to eat at set times. I have different work/play hours every day, so going several hours between meals is no issue as I don’t have the cravings I used to while eating SAD and taking metformin. I have cut my metformin in half, sugars normalizing so will be able to come off metformin completely soon (started one month ago), weight loss 20 lbs so far, not starving, loving the food, don’t miss carbs. When I don’t have “good quality” food around, I just don’t eat. In addition, I now recognize true hunger, which peeks in only every now and then on my Primal diet. I don’t want to be extreme, so my fasts will be delayed meals caused by busy with work or play rather than scheduled,

      Gringo61 wrote on April 25th, 2012
  2. Every part of me wants to be wary of this, even though the evidence is pretty solid. I guess my semi-irrational concern, comes from meeting many anorexics who use this kind of info to justify very long “fasts”, i.e. the scary “ABC” diet. Then again, any information can be used for good or bad. Great article


    Carlos Morales wrote on March 15th, 2012
    • I come across this stigma all the time. People think of gaunt, zombie-like, figures when they hear the word fasting. I practice IF and I have gained strength and muscle, while losing fat. Check out my website, at the bottom of my “about me” page, and you will not find a picture of a gaunt zombie. I promise. In fact you might even say I look very healthy. 😉

      Matthew Caton wrote on March 15th, 2012
      • Yup Its true I have a friend that does IF and he looks like a Spartan lol

        mimi wrote on April 16th, 2013
    • I understand where you’re coming from on this, but IFing and anorexia are different. Do a google search on anorexia, and read some of the stories. One I read was about a woman that would drink a coke or two and smoke, but not eat anything else during the day. That is NOT what paleo or primal folks do when they fast! I would drink coffee, tea, or lemon water during the fast, and always break it with a decent sized meal (at least a half pound of meat, veggies, maybe some starch thrown in).

      John wrote on March 15th, 2012
    • An anorexic doesn’t need articles like this or any other to justify their actions. IFing is not close to being anorexic. When you suffer from anorexia you don’t ever had a “re-feeding” period. When you do eat, its so small and not much substance. When your feeding window opens for IFing you EAT and in my case eat a lot. I have been following a 16 hour fast/8 hour feeding window for almost 5 weeks. During my 8 hour feeding window I still only eat two meals, maybe 3 if its a hungry day. On average, just two Primal meals. My body fat has gone down, my lean muscle has remained. My CrossFit workouts have improved in all areas, strength, cardio, endurance…. I also feel better mentally. Can’t describe why, just an amazing side effect. 😉

      Tracy Seman wrote on March 15th, 2012
      • This is exactly how I feel as well. I’ve been dabbling with 24 hour fasts once or twice a week with the ocassional 16-8 (when I forget to eat) and I’ve never felt better. My workouts have improved and so has my body!

        Linds @ Linds Eat wrote on March 15th, 2012
      • Hi Tracy – could you please specifically describe the 16hr/8hr fast you do? I’m on hour 11 of my fast. I need to cut fat but need to keep strenght up for my training.

        Amy wrote on May 21st, 2012
    • I know what you are thinking, I am recovered from an eating disorder and I keep my IF between my husband and myself since I do not want anyone else labeling me or lecturing on how bad it is. The whole key to this is only fasting intermittently. You do not just fast indefinitely and then eat as little as possible. The key is to eat regularly and break up that pattern with the occasional fast.

      Team Oberg wrote on March 16th, 2012
    • Just remember that anorexics tend to eat almost nothing all the time – nothing with substance or real nutritional value. They have weights that are dangerously Lowe…but their bodies finally fail, but their brains are the last to drop out, coma etc. Worth noting? And it is extreme, abnormal. IF is not extreme.

      Michelle wrote on March 17th, 2012
  3. Nice job Mark!

    NWPrimate wrote on March 15th, 2012
  4. Inspired to do a 20 hour fast…starting…now! (Note to self: wife’s turn to cook dinner, so I should let her know I won’t be eating tonight.)

    A couple of questions, though.

    What about impact of caffeine during a fast? The idea of no food AND no coffee really strikes terror in me.

    Workout intensity? Should I just be a slug during the fast, normal activity (long, slow walks or bike rides), intense workouts? Intense workouts usually make me hungry shortly after.

    Jerry wrote on March 15th, 2012
    • Caffeine will actually increase catecholemine levels, and burn even more fat. So drink up. Black is best, a “splash” of milk won’t hurt, and sugar will hurt.

      You should keep activity low to moderate. Walking is great and will help to burn even more fat. Extended sessions of “cardio” will only be detrimental. Intense activities are great in the fasted state. Some anecdotal evidence supports increases in strength, probably because of the epinephrine. However, you should eat after an intense workout, because you may experience a drop in leptin, which will slow your metabolic rate and cause you to burn muscle. Contact me through my website if you need more advice.

      Matthew Caton

      Matthew Caton wrote on March 15th, 2012
      • I’ve heard (and kind of experience) that coffee holds off hunger too. Why is that?

        Erika wrote on March 15th, 2012
        • Caffeine is an appetite suppressant.

          Roanne wrote on March 20th, 2012
      • You’re describing my regime to a ‘T’! I started experimenting with IF recently having followed a primal diet for three years, but loaded a bit of extra weight over last Christmas which wouldn’t shift. At first I was worried about ‘lightheadedness’ or hunger, which was apparent during the first couple of goes. But it disappeared quickly and now I don’t notice that I haven’t eaten. In fact what I do notice is a heightened alertness and awareness which doesn’t necessaarily mean caffiene (although I drink @ 4 cups of black coffee a day), I’m buzzing before I have a cup! It’s become a routine for me now during the week but I eat healthily and heartily in the evenings and at weekends. I’m 179cms tall and weigh in at 73 Kg. Feeling good!

        Paul wrote on April 12th, 2012
    • I just did a 20 hour fast and had a good workout 4 hours before breaking it. I felt great all the time. Felt like I could go on like this for a very long time, but moderation is better than fanaticism, so I broke it and will repeat in a week or so. I’ve been primal since 3 months, so it came very easily and naturally to me.

      einstein wrote on March 15th, 2012
      • Did the 20 hours include night time?

        Debbie wrote on March 15th, 2012
    • I prefer to workout intensely during a fast since it boosts the body’s production of growth hormone. Read Mark’s articles about fasting after workouts for reference. Of course this is all about personal preference, but it can help you get the most out of your fast. As a bonus, pushing past hunger helps you appreciate your food much more.

      Team Oberg wrote on March 16th, 2012
    • Hey I start my fasts after lunch usually counting it from about 6pm to 6pm ..for ex lastnight to now about 21 hrs into my fast i weigh 4 pounds less… but i do exercise everyday which accounted for 2 extra pounds of weightloss and i have been eating primal for almost 2 weeks before this fast so my body isnt in shock to the fasts anymore… hoping to lose a good 15 pounds before i stop the fasting ..hopefully by sunday for football party lol

      Jessica wrote on September 27th, 2012
      • point was i always have coffee! it kickstarts my metabolism so i workout for an hour after 2 cups and like i said i continued to lose 2 extra pounds after the coffee and workout

        Jessica wrote on September 27th, 2012
    • While caffeine may suppress appetite and help to burn fat – you should be reminded also that it places a lot of strain on your internal system and especially liver and kidney. If you must take caffeine – take the green coffee extract and/or guarana.

      It appears that many seem to view weight management and nutritional supplements as an activity that can utilise individual approaches. We need to bear in mind that the human body functions via an intricate relationship of complex systems that ideally work to maintain homeostasis.

      For this reason alone there are always pros and cons of ingesting anything. The best thing you can ever take while fasting is WATER. Not distilled water either.

      Why? Because fasting is a detoxification process and will release feel good into the brain – but you will need to flush out all those toxins that your body has stored to gain full benefit. If you can’t handle a full water diet, try miso soup in the evening (full of nutrients) to aid your liver and kidney function.

      After 48 hours appetite will decrease and supposedly the production of grehlin and if you make it to day three you may have halved your GI.

      If you break out and celebrate by a great sugar – insulin spiking feast you will find you quickly regain your appetite and lose any benefits you gained. Yet if you want to continue the system balancing approach – try day 4 onwards to wean yourself back onto foods via vegetable juices (and fruits in balance). Include some fibre and protein and try to stick to this combination to maintain strength and rebuild your metabolism. This is another area where there is conflict opinion that juices etc (fresh not processed) create an insulin spike and should be avoided for weight training. If the vegetable and fruit juice is a balance of the right nutrition – it can in fact assist the body. For example – Carrots are listed with a high GI rating and so are Beets. Yet Beet juice included in your mix will actually help to balance blood sugar. Carrot juice is well known antioxidant and for Vitamin A and B group vitamins – but is also a lesser known phytonutrient – currently being researched for its ability to detoxify and prevent colon cancer. I won’t bore you with the values of other veggies and fruits. The point is – that when in a non processed juice format (some fibre retained) the insulin hit is actually supporting the live energy and nutrients to get quickly into your blood stream, wake up and activate your body systems. Less energy is needed to break down the nutrients from “waste” and that allows greater absorption of the good stuff to give you more power and energy to spend on your work outs. If really worried about the increased insulin spike, combine with protein powder and ice to make a balanced smoothy. Its like high octane instead of 2 stroke.

      If you are only interested in fasting for fat burning and not detoxing and improving your health – remember that detoxing is actually supporting your body systems so that you can process and burn those fats. Fasting on water alone for three days will maximise the benefits if you don’t blob out afterwards. Water will also assist you from side effects of fasting – such as mild headaches etc. from caffeine withdrawal and other toxins.

      If you fast for spiritual purposes or other “endurance” fasting over a long period you will lose weight but you also train your body to adjust to “starvation mode” – this is why the lady who wrote above lost less weight than she should. Alternate and intermittent fasting combined with a health supporting diet that utilises nutritional value will do more than any other type of regime. Exercise before breakfast will also help to curb the hunger cycle during non fast periods. The other important factor to note is that just as our finger prints are individual and unique – so are our bodily responses to diet and exercise. There is no “one” perfect way for everyone. We need to listen to our own bodies – also to evaluate our current position (what is out of balance through noting health issues and conditions) and then working out the relationship plan best suited to us. This takes time and we can benefit from a whole system approach and advice via naturopath and nutritionist who is also sympathetic to our motives i.e. – health, or fitness, or physical appearance.

      A few years ago someone in my neighbourhood died – someone who was a health and fitness instructor – who also was only in his thirties and had been thought to be in perfect health. This person had apparently been approaching weight training with extreme approaches and popping some “health” pills – causing renal failure. If you are going to fast and do HIIT or other intense cardio etc. I recommend you check your heart and organ health before. Otherwise, consider using it as a tool to detox and rebuild vitality for some serious post fast fat busting and workout.

      Just some alternative input to think about.

      Best wishes

      vivienne wrote on April 27th, 2014
  5. I have been IF:on on and off for almost a year now but recently I was told that long term fasting raises cortisol-levels which stress the body if done for to long. I remember it having something to with the circadian rhythm.

    If somebody could shed some info on this it would be appreciated.

    Pasi Hautala wrote on March 15th, 2012
    • I am also interested in thoughts on this. I do the occasional IF or or restrict eating to an 8 hour window, but have been told that anyone suffering from burnout or thyroid issues shouldn’t do this as it raises cortisol levels and puts more pressure on the body.

      cpb wrote on March 15th, 2012
    • I’ve read that the study this information came from was taken out of context. Cortisol will increase during the fast, which is natural and a part of keeping blood sugar stabilized. However, mean cortisol levels did not increase. Only “short-term” increase were found.

      Due to the circadian rhythym, I find that fasting is best in the morning and early afternoon, and eating is best saved for the late afternoon and night. This way eating patterns will be in-sync with the diurnal rise and fall of cortisol. Cortisol is high in the morning and drops at night. Fasting in the evening may not be the best thing because then you will be elevating cortisol at night.

      Matthew Caton wrote on March 15th, 2012
      • This reminds me of The Warrior Diet philosophy. It’s been forever since I read the book though, but I do recall it speaking about this way of eating. Have you read that book?

        Emma wrote on March 16th, 2012
    • Intermittent fasting was one of the changes that helped me get rid of my (admittedly minor) asthma. Thus I would expect that it actually helps to reduce long term cortisol-levels or at least inflammation.

      Victor Venema wrote on March 15th, 2012
    • I don’t know if anyone answered you yet, but what your talking about is the actual fast. Like a 48hr fast vs a 16-20h fast. If you break your fast within even 24 hours you don’t have to worry about that. :) VERY long fasts are what raise cortisol levels.

      Lita wrote on August 1st, 2012
    • I’ve been very interested in and have pealrnosly conducted fasts on my own for the past 25 years. I am currently an alternative health practitioner and have helped people work through many health issues using fasting. For these reasons, I buy every book I can find on the subject. Juice fasting, has been my favorite type of fasting so I was particularly interested in this book prior to receiving. Unfortunately, I wasn’t as enthusiastic after reading it. I found this book in congruent, disjointed and incomplete. It had a lot of anecdotal and miscellaneous information that might be interesting for trivial knowledge about the subject but not congruent enough to be useful when conducting a proper fast. If you want to read a book on juice fasting that’s complete, to the point and relevant, I’ve never read anything better than the old standard by Paavo Airola How to Keep Slim, Healthy and Young With Juice Fasting . It’s amazing how ahead of his time Airola was, after all these years, it still the best book on the subject.

      Berivat wrote on December 19th, 2012
  6. “They were also monitored while eating a normal diet during an additional 24-hour period.” I’d love to know what this “normal diet” consisted of.

    Also, it mentioned the increase in HGH after the fast. Did these people exercise fasted at all? Is it recommended to break your fast THEN exercise?

    Jeff wrote on March 15th, 2012
    • Exercise fasted, it further boosts your HGH production. In fact, people who don’t participate in regular fasting should always train in the morning before they have eaten. I always work out before I eat. Check out the website “Lean Gains” for fasted training information

      Team Oberg wrote on March 16th, 2012
  7. So much of the fasting information I’ve read has to deal with weight loss or body fat loss. Are there benefits of fasting for a lean, athletic female (or male for that matter) that doesn’t have trouble staying lean in their current primalesque lifestyle?

    Joletta wrote on March 15th, 2012
    • I’m guessing that the Part 2 will go into that

      Carlos Morales wrote on March 15th, 2012
    • The study Mark referred to as improving insulin sensitivty was done on young men with who were not obese. It also includes results that show increases in other bio-markers as well.

      Matthew Caton wrote on March 15th, 2012
      • I understand that the study was in non-obese men but it still measured fat oxidation and weight loss. If anything, I trend toward too lean and I don’t need to lose any weight. The study on the non-obese men also mentions that they were hungry during the fasting days. I also don’t like being hungry!

        So I was referring more to the benefits of fasting in lean people at a healthy weight that they have maintained for years that don’t have fixations on meal timing and quantities.

        Joletta wrote on March 15th, 2012
  8. Hi all – can anyone recommend the best book about diabetes and primal diet? my co-worker is so sure he needs to constantly eat to keep his “blood sugar” up so he doesn’t “pass out” that he would never consider fasting. I am doing my best to educate him about primal wisdom (and maybe he will read PB if I shove it at hiim), but I will buy him a book if it specifically in detail discusses diabetes and carbs! thanks!

    Wendy wrote on March 15th, 2012
    • Google this article, you can access it free on-line:

      “Role of glycemic index and glycemic load in the healthy state, in prediabetes, and in diabetes.” Am J Clin Nutr. 2008 Jan;87(1):269S-274S.

      Tim wrote on March 15th, 2012
    • Fiber Menace by Konstantin Monastyrsky ( discusses, among other topics, diabetes and it’s relationship to carbs/fiber. I read this book before I found MDA & the Primal way of life and I found it enlightening. LOTS of parallels with the Blueprint…

      Paul wrote on March 15th, 2012
    • I also have some fine tuning questions about Primal and diabetes, but on the whole I’ve found that the primal lifestyle has been good for me and helpful in keeping blood sugars more regulated. Gary Taubes’ Good Calories Bad Calories addresses the issues pretty well.,_Bad_Calories

      EmmaSofia wrote on March 15th, 2012
    • I can tell you from the personal experience of managing my son’s type 1 diabetes mellitus that the primal lifestyle is absolutely an option and a good one. The key is to watch the insulin levels carefully because you’re going to have to adjust them downward, and fast. My son went from using nearly 55 units total per day to now being in the low 30’s, almost half, which is great from two perspectives 1) more insulin means more fat storage and more hunger pangs and 2) the law of small numbers means that injecting for 10 carbs at a meal is much safer than doing the same for 100. This is because, if you’re wrong, if it’s really 8 carbs and not ten, then you’ll be a tiny bit low… but being wrong by the same percent at 100 carbs can mean a dangerous life threatening low (a major cause of premature death for type one diabetics).

      Obviously any diabetic should consult with their endocrinologist before changing your insulin but I recommend looking into the paleo/primal/ancestral lifestyle. It’s more than just possible, we think it’s great. He’s a lot more stable than he’s ever been before (and thriving, he’s already almost taller than I am and he’s 11) and that’s a very good thing.


      Tim wrote on March 15th, 2012
    • There is web-site
      Did your friend read the book by Dr. R.Bernstein “The diabetes solution”? I am sure he would find the story of Dr. Bernstein quite remarkable and inspiring and probably it is better to get the book first (from any public library) or even free on-line

      Galina L. wrote on March 15th, 2012
  9. The possible implications of the GH increase during a 24 hr fast are very interesting.

    Casey wrote on March 15th, 2012
  10. I like intermittent fasting, but I think you’ve gotta really be adapted to a primal type of diet for it to work. You’ve gotta have good blood sugar control, and stress and sleep under control for it to work well in my opinion.

    Burn wrote on March 15th, 2012
    • A normal metabolism would be helpful, but just extending the time about 30 minutes every morning before eating is an easy way to break into fasting with a bad metabolism.

      Matthew Caton wrote on March 15th, 2012
  11. I find intermittent fasting to be so easy to do compared to calorie restriction.

    Also, if there isn’t anything Primal around to eat, I have no fear that my muscles will wither away if I simple don’t eat until I can eat Primally!

    Cori wrote on March 15th, 2012
  12. I have been eating one meal a day (dinner) and I found after a few days, that I felt more energized and stronger. I workout 6 days a week and have not felt weak, tired, or dizzy because of it. I found the hardest part about it is enduring to constant barrage of CW and explaining why what I’m doing is ok. But its easier when I look in the mirror or when I visit the doc and my resting BP is down. The key for everyone is to try and see what works for their bodies. This works for me and I thank Mark and my Primal family for sharing stories and giving support. This has definitely changed my lifesyle for the MUCH better.

    PaddyMac wrote on March 15th, 2012
    • Isn’t funny how people with metabolic and health ailments can look you in your healthy face and say what your doing is going to kill you? It’s sad that some people are so bound by stigma.

      Matthew Caton wrote on March 15th, 2012
    • I could not have put it better been doing the same for a month now lost 22 pound in two months and have never felt so good when exercising but it’s not for everyone I’m a shift worker and it’s the only eating routine that has ever worked all the best Greg rees

      Greg wrote on April 29th, 2012
  13. I fast 16/8 pretty much every day. Sometimes my fasts extend to 20/4 or something like that… definitely don’t be scared of fasting.

    However, I have not ever, not once, gone over 30 hours. I’m basically at my ideal weight, so I really have no desire to do it for fat loss, but I would consider it just as an experiment of sorts — however, I largely enjoy eating, so I’m not sure if I will at this point in time.

    Lastly, Marilyn Manson wasn’t on The Wonder Years – per

    IniQuity wrote on March 15th, 2012
    • +1 on the Marilyn Manson comment.

      Joe wrote on March 16th, 2012
  14. I am trying more/longer fasts now – but without getting too crazy about it – what happens if you have ONE handful of nuts, or one slice of raw cheese, or some kombuchka – does that entirely elimiate all the benefits of the entire fast????

    Wendy wrote on March 15th, 2012
    • I don’t think so, since foods lacking carbohydrates will have little to no effect on insulin levels and sensitivity. It may blunt some of the effects, but probably not all of them.

      Tim wrote on March 15th, 2012
      • Protein and dairy have a large effect on insulin.

        Carlos Morales wrote on March 15th, 2012
      • Fasting is fasting. The whole point is to give your digestive system a break. Even coffee is not ideal because it tells your body food is coming – digesting coffee is using digestive system. If you want to experience the full benefits of fasting, it needs to be done for at least 24 hours at least once a week. It gets easier every time. READ what Mark has written. Stop asking foolish questions and take the time to read what he has prepared. Another wonderful writer on this subject is Brad Pillon of Eat Stop Eat. Thank god for Mark and Brad.

        Raquel wrote on July 30th, 2012
        • I doubt you’ve actually READ a WORD of Pilon’s writings about fasting. If you had, you’d know that he drinks black coffee daily on his fasts AND he says it is ok for people to drink unsweetened teas and coffee on the fast.

          Drumroll wrote on January 3rd, 2013
    • +1 about the kombucha! I’m in the middle of a 20 hour fast right now and I have a bottle of kombucha right next to me… Calling me… Begging to be consumed…

      Paul wrote on March 15th, 2012
    • Your insulin levels will still rise, definetely not as much as if you eat ice cream though. Depending on how much or how little you ate it would probably take a few hours before insulin levels fell back to fasting levels. For further advice contact me via my website.

      Matthew Caton wrote on March 15th, 2012
    • I recommend checking out for more information about the 16/8 fast – it suggests a splash of cream in your coffee is ok, but anything even getting around to 50 calories is not good for the fast. I would not risk eating the handful of nuts or cheese, it’s not going to temper your appetite at all and will probably make you hungrier. Snacking is more of a psychological mechanism, just don’t do it :)

      Heidi wrote on March 15th, 2012
      • The guys sitting next to me at Mark’s presentation just mentioned the same site… And it seems to line up with Mark’s bullet points on shifting/conforming eating patterns to your body (eat when you’re hungry) as opposed to a set of societal/customary norms (“Breakfast is the MOST IMPORTANT meal of the day”… “Eat 6 small meals a day”… etc.)

        Primal Texas wrote on March 15th, 2012
  15. I’ve been doing daily 16 hour fasts with a relatively low-carb paleo diet during my 8 hour feeding window. Is this long enough of a fast to get the fat-loss benefits or should I try alternating days like in some of the studies mentioned?


    Steve H wrote on March 15th, 2012
    • Alternating days can be hard if you are trying to maintain muscle or train in the Primal context.

      You will start to burn almost entirely fat after 12 hours of fasting, however, after 18 to 20 you will start to break down protein to stabilize your blood glucose. Not a significant amount, but it’s something to think about.

      If you want to split the difference you could do a 20 hour daily fast, but you should eat about an hour after you workout. The 20 hour fast would give you 8 hours of pure fat burning time everyday. Of course you could just change the feeding window back and forth anywhere from 4 to 8 hours whenever it suits you. For further advice contact me through my website.

      Matthew Caton wrote on March 15th, 2012
      • I’m currently eating in an 8 hour window that changes from day to day. Sometimes I reduce the window to less than 8 hours. Seems to be working well so far. However, when it’s time to eat, I really enjoy eating at least 1 lb. of grass fed beef or 8-12 pastured eggs! I absolutely could not do it (I don’t think) if I wasn’t eating at least 1 pretty big meal per day.

        TJ wrote on March 15th, 2012
      • Awesome reply! Thank you kind sir.

        Steve H wrote on March 16th, 2012
  16. Worked like a charm for me to lose the stubborn fat. Esp when combined with low intensity exercise in the fasted state. The high intensity stuff on the otherhand left me feeling a little less inspired.

    2THDOC wrote on March 15th, 2012
  17. One of the best benefits of fasting is that you learn that you can decouple yourself from the 3 meal a day norm and not have your world come crashing in. Fasting can help establish a different relationship with food that makes you realize that you are in control of the Sara lee frozen cheesecake rather than the other way around

    Randy Hagenstein wrote on March 15th, 2012
  18. Wendy, from personal exp I find that snacking during the fast only seems to stimulate my appetite and complicates what is typically an effortless fast.
    You’re bound to inhibit some of the hormonal benefits as well.

    2THDOC wrote on March 15th, 2012
  19. Did anybody else picture Fat ‘B’ from Austin Powers when reading about the obese Scotsman?

    Stevemid wrote on March 15th, 2012
    • LOL “Get in my belly!!”
      Having been primal for 32 days, I find my hunger is usually much less insistent (which is really liberating)… but I haven’t tried IF yet. Does the hunger stay mild? Does energy stay OK if you don’t get too strenuous? Thanks Mark, and for all the info Matthew Caton, I’ll check your site next.

      Tom Bassett-Dilley wrote on March 15th, 2012
  20. 1 meal a day has worked for me for years. Low Carb Paleo w/IF I call it. Keep setting them straight Mark!

    Grokitmus Primal wrote on March 15th, 2012
  21. I’ve given alot of thought to fasting but am not sure how/whether to proceed since I am diabetic (type II) and take daily long-term acting insulin injections. I’ve suspected the insulin is inhibiting the positive effects of the primal lifestyle. Any thoughts and suggestions would be most welcome.

    EmmaSofia wrote on March 15th, 2012
  22. Just a question – one of the related posts was Ten Sure Ways to Sabotage Weight Loss, and it includes things like skipping breakfast and eating one meal a day as ways to sabotage your weight loss. That seems inconsistent with the post here.

    Ed wrote on March 15th, 2012
    • I’m confused about this too. I struggle to eat something for breakfast each day. Now I read that it’s better to skip it? Put us on the right path please!

      Jeff wrote on March 15th, 2012
      • The association between breakfast and weight loss is just an association – as we saw in the previous post about red meat, associations cannot prove that A causes B.

        The observation is that people who eat breakfast tend to lose more weight than people who don’t. Why is that?

        *Maybe breakfast helps weight loss.
        *Maybe the people who have time to eat breakfast are less busy and less stressed than those who don’t eat breakfast.
        *Maybe the people who don’t eat breakfast at home tend to snack on bagels and doughnuts instead.

        All valid explanations as to why there is an association.

        Tim wrote on March 15th, 2012
    • I think that post was from 2006 (the year May 22 was a Tuesday). Marks thinking has evolved. Unfortunately, he doesn’t year mark his posts, so it’s hard to tell sometimes what his latest thinking is.

      Chris Johnson wrote on March 15th, 2012
      • He doesn’t year mark, but the first comment will have a year on it.

        Miranda wrote on March 16th, 2012
  23. I’m doing John Romaniello’s Fat Loss Forever diet (lifestyle) and having success… check it out

    Michael Custer wrote on March 15th, 2012
  24. Fasting is DA BOMB! :)

    semir wrote on March 15th, 2012
  25. just started tinkering with 1 meal a day and its been great…. sleep is prolly the aspect of my life that benefits the most from fasting

    Jake wrote on March 15th, 2012
    • When do you have your meal? I am interested because I would like to mess around with fasting, but I don’t want to eat such a large meal near my bedtime.

      Nick wrote on March 15th, 2012
      • Usually around noon or 1 pm… by the time I’m ready for bed I start feeling a little hungry but its not a problem and I fall asleep much easier and get into a really deep sleep

        Jake wrote on March 15th, 2012
  26. I appreciate that you are writing for what you think is a relatively mentally healthy group, but please consider the ramifications of what you are saying on the unhealthy, in particularly, people with eating disorders. These sick folks want any excuse to think that they are doing the right thing by starving themselves. That story of the Scottsman just scares me because I’ve learned a lot about anorexia and it is a deadly disorder when people of a healthy weight starve themselves for months on end or severely restrict their calories. It is a serious mental disorder and I know that they aren’t the audience you meant this recommendation for, but you are on the internet :)

    If you want to understand the mindset that leads to anorexia, I highly recommend Portia de Rossi’s book “Unbearable Lightness”.

    Stephanie wrote on March 15th, 2012
    • Intermittent fasting is not in any way related to anorexia. (I didn’t go to your link so this doesn’t directly address that) I was aquainted with a women who suffered from anorexia. She didn’t IF….she starved herself. Allowed herself a couple of bites of food over the course of the entire day and then would work out like a fiend. As you said it is a serious mental disorder. The concept of an intermittent fast doesn’t create anorexics

      bbuddha wrote on March 15th, 2012
    • You can’t keep truth away from people because someone might misuse it. I think conversely, an anorexic reading this might find a little education about how to reach their desired end in a healthy way. If anorexia nervosa really is a mental condition, they don’t need an excuse and pointing to someone saying an occasional fast in the context of natural eating will produce optimal health, would not really be reading this anyhow. You can’t control how people will misunderstand your message.

      Joshua wrote on March 22nd, 2012
  27. Awesome, Mark. I used to fast once a week (the feed/fast approach advocated by John Romaniello). I loved the increased energy during my fasts, so I have stepped it up and now do a “mini-fast” of 16 hours on workout days and 24 hours on rest days. Conventional wisdom be damned–it hasn’t hurt my workout intensity, muscle mass, or energy/productivity. If anything, I’m more productive and energetic during my fasts. I’m happy to see the “4 meal a day” recommendation be debunked, because in retrospect it was a *total* pain-in-the-ass.

    Daniel Wallen wrote on March 15th, 2012
  28. I’m a little over 400lbs, and have been just eating one large meal a day for a few weeks now. Not due to weigh for a week, so no idea about weight loss yet, but I now have much more control over my food – I had been really struggling with craving, but somehow eating one meal a day gives me more self control – not sure why, but as its working, who cares why!

    Lee wrote on March 15th, 2012
    • What does your one meal consist of?

      Tee wrote on March 18th, 2012
  29. I have been using intermittent fasting with great succeess to lower and maintain my bodyfat percentage. My last measurement from skinfold calipers was 7.3%. I’m actually in the fasted state as I type this.

    If you have never tried fasting you will notice the effects of the catecholemines almost immediately. The catecholemines epinephrine and norepinephrine will reach a plateau after around 12 hours of fasting and will remain elevated after that. As Mark said the epinephrine will give you energy, but I would like to add that you will also feel very focussed. Coupled with the mentally calming effect of the norepinephrine, you will experience a natural high. You will feel calm, focussed, and energetic. You will become lost in anything you put your mind to. Personally, I look forward to my fasted state every day.

    Tip: Drink a cup of coffee in the fasted state and you will increase your serum level of these catecholemines.

    What’s not to love about IF?
    Increased growth hormone, autophagy, glucogan, insulin sensitivity, catecholemines, with decreases in bodyfat, and serum insulin.

    It’s terrible that fasting has such a negative stigma on it. Most people think that my daily fasting period is bizarre and I’m going to lose all my muscle mass. If you check out my website you’ll see that definetely isn’t the case. In fact, some research indicates that training fasted can lead to greater protein synthesis post-workout.

    Contact me through my website, linked through my name below my picture, and I can help you create the best fasting routine for you.

    Matthew Caton

    Matthew Caton wrote on March 15th, 2012
    • Last year I went on a 10 day water fast in an attempt to find out if I had food/sugar allergies. After the first 48 hrs the hunger pains went away and it actually got easier and easier as the fast progressed. More to the point, the catecholemines release caused a clearing of my mind that was almost spiritual. I now have zero qualms regarding IF and have had great strides forward in my health after fasting.

      MadMav wrote on March 15th, 2012
      • That’s great MadMav. But do you have a website we can contact you through?

        Tim wrote on March 15th, 2012
        • You beat me to it, Ed…;)

          ealachan wrote on March 15th, 2012
        • Love it!!:)

          Chris wrote on March 15th, 2012
      • After reading an article in ‘Harper’s’ magazine a month or two ago, entitled, “Starve yourself to vigor”, I embarked on a 7 day fast. I am 56 years old, have been a vegan for 7 years, take exercise very seriously, both cardio and some weights and am not overweight at all. I felt euphoric from day 2 on and had boundless energy, doing all my normal activities, including running, playing tennis and doing weights. On the morning of the fifth day I decided to call off the fast because I had lost 13 pounds and thought that was enough. I really felt no hunger pangs and felt like I never had to eat again. Since then, I have done numerous one day fasts and find that they are the only way to curb eating that works for me. When I became a vegan 7 years ago my weight dropped to what it was when I was 17 (172 lbs and 6 ft tall). Now it sits at 163 lbs and I feel great. I also feel a spiritual aspect to fasting, a calming of the mind and body. It is great to hear from people who have had similar pleasant experiences.

        David Crowther wrote on April 27th, 2012
    • You fast every day?

      I would love to learn what a good fasting routine would be for me but I can’t pay for a consultation. It’s great that there are people like you out there that can provide real help though. Thanks.

      Emma wrote on March 16th, 2012
    • Matthew-
      No, it’s not such a bad thing that people are a little slow to hop on the latest bandwagon.

      I skip meals myself, and it does work, but I waited until I knew metabolic markers were in line, like rT3, leptin, insulin, and some others.
      People who love their IF just need to realize that it can be a very foolish thing to do if one has a lot of weight to work on and their metabolism is wrecked. Everyone is a bit different.

      I just wish Mark would be a bit more responsible and tell the whole story about when someone may not be ready. Some of us are not 5% away from ideal weight, or trying to get from 13% body fat to 11.5% or whatever!

      I just heard a good interview that Moore did with Kresser about dietary causes for low T3 thyroid hormone and one of them is fasting. Know your rT3.

      DFH wrote on March 26th, 2012
  30. Okay I have been always weary of fasting from my past history with conventional wisdom. I always thought it was for those people you see on Oprah with eating disorders.

    My coworker and I were just talking about this topic last night! I swear Mark can hear us talking and posts with all the information we need (and the points to pretty much prove that everything I was saying was wrong haha). Also, this post uses science, which I am very found of being a biologist.

    All in all, I think I am going to give intermittent fasting a go. Slow at first and then see where it takes me. The great part is it will be fun breaking my fast with a big ass steak!

    Ed wrote on March 15th, 2012
  31. For most of the past year I thrived on IF (intermittent fasting) and in the past month I have experimented with ADF(alternate day fasting.) For me, fasting is very calming. My gut is very quiet and the other bodily systems follow suit and yet I have high energy. I don’t suffer any weakness at all and the only “weird” comes in realizing just how much time I typically spend preparing, eating and cleaning up after meals.

    Nance wrote on March 15th, 2012
  32. I’ve been paleo for about a year now and have lost about 30 pounds… pretty typical story. But it seemed like I had stalled out, with some obvious fat yet to burn. I came across Richard Nikoley’s book “Free the Animal” and was reminded of intermittant fasting. I’ve been doing a 24 hour fast 1-2 times a week for the last month, and have found this very effective in burning fat that I have been having trouble getting rid of. I’m down about 5 pounds, but aside from that, I can see a big difference in how I look. My muscle tone in my arms and shoulders is much more defined, and my gut is slowly shrinking away, much faster than it had been for a while now.

    Brian wrote on March 15th, 2012
    • Congrats on the action and results.

      Not sure what you mean by “24 hour fast”, but if you don’t eat from, for example, Sun night to Tues morning, that’s actually more like a 36 hour fast. I would recommend one meal – either breakfast or dinner, NOT lunch – on fasting days, as it is after about 24 ours that you start losing muscle.

      Jeffrey of Troy wrote on March 15th, 2012
    • Yes…actually that is strangely similar to my experience. I’ve been primal for about a year, and lost about exactly 30 lbs. I have to give credit to the leangains program for outlining a sensible approach to IF. It’s easy, I just skip breakfast and make a big lunch. It drives me crazy when I hear that a paleo diet is hard to maintain. How hard is it to skip breakfast, and have bacon for lunch?

      Eating in Orlando wrote on March 15th, 2012
  33. Fasting is absolutely helpful. I first got serious about fasting after I had an eating disorder and gained a bunch of weight (I got over the ED first, mind you, that’s the first step). I lost the excess fat effortlessly, and as I experimented more and more with fasting, I found that a fasted state made me feel better, more alert, and more productive. Nowadays I try to fast for at least 12 hours overnight, every day, with occasional 18-24 hour fasts thrown in on a really good day. I also do all exercise fasted, except for Kung Fu. I’m a major proponent of fasting for fat loss and general well-being.

    Benjamin wrote on March 15th, 2012
  34. I tried a 24 hour fast for the first time yesterday and my enegery was through the roof! As soon as I got home from work I began my workout and then waited an hour before eating my meal. I plan on doing this from now on every 3 days, which will also be my workout days. Every other day I fast 16 hours and eat 2 meals in a 8 hour window.
    I’ve lost 40 pounds since late December following the Primal Blueprint and I love it!

    Steve wrote on March 15th, 2012
  35. OK, so I am not opposed to intermittent fasting, or any fasting, per se … but where do you draw the line between fasting and anorexia?

    outlookishazy wrote on March 15th, 2012
    • Anorexia is a psychological disorder. If you have or are prone to such a disorder, you may glom onto any information such as this to bolster your rationale for your disorder.

      But this post isn’t about folks who are sick with anorexia.

      HillsideGina wrote on March 15th, 2012
    • Anorexia is continuing to lose weight through extreme dietary measures when one is at 85% or less of their ideal body weight. So, as long as you aren’t underweight, by this definition you can’t be anorexic.

      Alyssa wrote on March 15th, 2012
      • TRUE

        Mary Titus wrote on March 15th, 2012
  36. I’ve always felt the “three meals a day” mantra was a bogus modern construct not based on any science.

    We are so over-fed and food-obsessed in Conventional Wisdom that we call any period of not eating a “fast” and not a normal behavior. But we really don’t know shit.

    Those of you asking how to fast, when to fast, wanting a plan layed out for you – go experiment on yourselves. Do it your way, see what happens.

    HillsideGina wrote on March 15th, 2012
    • Here here!

      We tend to fast on the weekends. We cook food in the morning and just let our kids graze as they wish. It amazes me at ages 2 & 5 how in tune they are with their bodies. Many nights they just don’t feel like eating dinner–so they don’t!

      For me, fasting was more getting over the mind-set that I had to eat. Having been a diagnosed hypoglycemic since I was a kid, I had trained myself to eat every 2-3 hours to prevent low blood sugar. Was I ever a slave to the clock! My first time trying a fast (eating dinner and then not eating until noon the following day) , I had to get over watching the clock and to just listen to my body. Like many people have attested in this post, I felt energized and alive! What a great feeling.

      I do find, as I still turn to sugar in times of emotional turmoil, that it takes me a few days after a binge before I can try fasting again. I can really feel it in my body that it is not ready for a fast.

      Happycyclegirl wrote on March 15th, 2012
  37. I also switched over to the “Warrior Diet” of 1 meal per day several months ago and find it to be the most liberating choice I can remember. Depending on mood I might have 1 or 2 very small snacks, but almost all of my calories come in the form of one giant 4 hour feast at the end of the day. Took a little while to adjust to eating that much, but it was well worth the effort and it’s so nice not constantly worrying about my next meal during the day. A Primal based Warrior Diet is something everything should look into. That being said, I’ve been eating 20/30/50 C/P/F for some time now and CF’ing 5 days a week and can not get lower than 12% bodyfat. So while I love this style and convenience of eating, for some reason I don’t seem to reap the same benefits as others do with the easy fat loss. Ehh, just my input from a few months of experience with daily fasting.

    Topshelf wrote on March 15th, 2012
  38. Without a doubt, fasting is one of the things that really helped me drop about 40 pounds of fat last year. I first tried a full day fast in June (I think it was about 36 hours), and really took to it. I did feel hungry, but at the same time, felt better when doing it. I started skipping breakfast during the week and doing at least 1, sometimes 2, 24 hour fasts in a week. Not sure, but I think I may have been overdoing it a bit toward the end of last year, and I’ve been eating more frequently recently. I still have another 40 pounds of fat or so to get to where I want to be, and I think I’ll get back to more regular fasting again after this weekend.

    But yes, I found it very effective, and quite enjoyable and empowering too. It was great to know that I could easily skip meals if need be. Basically, I used a 5-8 eating window during the week, threw in 1 24 hour fast, and ate a bit freer on the weekends (although I usually just ate breakfast and dinner).

    John wrote on March 15th, 2012
  39. Ok… Paul from the Wonder Years is not Marilyn Manson…

    Dave, RN wrote on March 15th, 2012

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