Fasting Makes You Active
It’s a familiar image we might attribute to stereotype: a sluggish, maybe portly individual lying prostrate on the couch, his/her front littered with Dorito crumbs. Could there, however, be truth behind the picture? Is there indeed a connection between incessant snacking and chronic slothdom? Or considered another way, is there a connection between fasting and being active? As a long-time fan of intermittent fasting (and a believer in the research behind it), I’m convinced. A study out this month sheds even more light on the relationship between lethargy and continuous eating.
For decades now, conventional wisdom has told us that we should eat regularly throughout the day to keep our blood sugar steady. With three regular meals and at least two snacks, we’re counseled to keep our bodies in a perpetual postprandial state. However, newer research, including this month’s study from ETH Zurich, questions this assumption. Scientists focused on the opposing relationship between a transcription factor, Foxa2, and insulin. Foxa2 is found in both the liver and the hypothalamus, the central command for hunger regulation. It has a hand in the expression of two eating and physical activity related neuropeptides, melanin-concentrating hormone (MCH) and orexin. When insulin is present, as it is during and after eating, Foxa2 and the related MCH and orexin are reduced. However, fasting mice showed consistently high levels of Foxa2, MCH and orexin. The researchers then found that “hyperinsulinemic, obese” mice showed reduced Foxa2, MCH, and orexin, regardless of whether they had eaten or not. When the scientists bred mice with continually active Foxa2 (immune to the counter effect of insulin), these mice showed high levels of MCH and orexin – and a correspondingly high level of physical activity whether they had eaten or not. The specially bred mice had low body fat as well as higher muscle mass.
Consider this study another nail in the coffin of conventional wisdom. (It also goes a long way in explaining the snacking couch potato association.) Fasting, even short, between-meal breaks, promotes the activation of Foxa2 and the resulting formation of MCH and orexin – as well as their activity-inducing effects. A simple survival principle explains this: a hungry animal needs to get up and move to find food. On the other hand, if we are constantly swimming in the insulin of eating and post-eating states, we’re undermining our own motivation (and biochemical stimulus) to get up and burn off what we just ate.
CW encourages us to never skip breakfast, bring along a mid-morning snack, make time for a good lunch, grab a mid-afternoon nibble and then have a good dinner. Oh, and if you can’t sleep, you’re supposed to have warm milk and a banana before bed. Our bodies are either eating or processing what we ate. There’s never a recovery period. Nary a resetting opportunity. We’re so focused on the hobby horse of “stable” blood sugar that we’ve forgotten that there’s more to the biochemical story of balanced energy. We make ourselves feel perpetually full to the exclusion of feeling anything else. (How about light, energized?) We continually raise our blood sugar and insulin levels and, in doing so, turn off the body’s chance to activate or upregulate other key substances that promote energy balance – and as this study shows, the physiological motivation to be active. Simple advice: skip the snack. (Besides, dinner never tasted so good as it does on a healthily empty stomach.)
Let me know your thoughts. IFers – have you found this principle to be apparent in your own experiments? Thanks for reading.
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Posted By: Mark Sisson
I love this. Years ago, the conventional wisdom said three square meals a days and that’s what I grew up with. I never get hungry between meals if I eat every 5-6 hours and my meals are “clean” (no starchy carbs).
I clicked too fast. I meant to add that I used to fast all the time for a day of too and have done juice fasts in the past and always felt great. I think it’s a great idea and good research!
Strangely enough oats are the only cereal that doesn’t give me the munchies, I can eat a bowl of porridge with fruit and not suffer from hunger pangs for hours. This may be because I am a Scot…
PS No I’m not eating oats at the moment, I’m trying for the full 30 days free of any cereal.
PPS I eat 4 times a day, and feel like I have good energy levels, even during this -12C snowy weather.
You know, Eat Fat Lose Fat mentioned a woman who experienced less hunger on soaked oatmeal than eggs and bacon (though the book promotes the eggs and bacon!). I would imagine that’s the exception rather than the rule, but it’s interesting to hear someone else had a similar experience. I know it wouldn’t be the case for me!
What amazes me is that we, as thinking, rational animals, often fail to examine, consider or even imagine what might have been the natural gustatory patterns of our ancestors, or at least the need for the gut to take a break.
Even more odd is our insular belief that eating small frequent meals is the right and healthy habit, even though the French and Spaniards hardly ever snack yet don’t suffer the obesity epidemic that continues to grow in our country.
I too am very carb sensitive. I noticed that over a period of two days I seemed to be retaining water. It corresponded with a soup that I made from 3 pounds ground beef and one pound each of green beans, spinach, and carrots. I figured it was probably too carby for me to be having one bowl per day.
I ditched the soup on the third day and had chicken and olive oil for lunch, and a small handful of almonds for dinner. I didn’t eat until lunch today after that. I felt much better and broke through the weight loss plateau I’d been on. Yay!
Anyone have any experience or know of any research about IF while lactating? How does it affect milk production?
I don’t know from experience but I thought I’d throw my two cents in. I think it’s most important to be sure you’re getting the proper nutrients in – plenty of saturated fats and fat-soluble vitamins. Think eggs, cheese, butter, meat, coconut oil, etc.
I really don’t know if IF affects milk production, so I won’t specifically give advice on that part. But unless you hear of a valid reason why not, maybe you could try easing into it? If you’re used to eating three meals a day, try delaying breakfast for an hour and eating normally after that. Then after you get used to it, try eating a really good breakfast and see if it can hold you till dinner. However you do it, just work into it gradually.
If you feel comfortable and satisfied, if you’re consuming enough healthy food and your milk production stays up it might be all right. But I would really listen to your body to make sure it’s a positive thing.
I’d certainly love to hear if someone else has personal experience with this, or know someone who does.
First off, I love the MDA website and am a big fan. I really want to like the IF/MD lifestyle but have some concerns that I was hoping you could help answer.
I am an ex-jock and division I two-sport athlete. I have spent much of my life in the gym and at the training table. However, now in my early 30′s, the main reason that I train at this point is for aesthetic purposes (I admit it!) and trying to stay lean and fit. The science behind your concepts do make complete sense. However, at the Olympia this year in Vegas, I met several of the “big wigs” of paleo/crossfit/IF lifestyle who’s stuff I had been just began to read on the internet. After meeting them, I left thinking “I already look better than them doing more traditional stuff.” After meeting several die-hard crossfitters who subscribe to the IF/Paleo diet principals over the past few months…it confirmed what I saw at the Olympia. Most folks out there who are participating in what I would term as non bodybuilding type workouts and diets really do not have impressive physiques….they just look skinny….not fit. Of course, yourself and Arthur Devany are two notable exceptions.
My wife is an IFBB professional figure competitor and model and eats 6 times a day and does traditional bodybuilding splits and long cardio sessions. She looks fantastic year-round. Everyone that we have ever met in the fitness modeling/ bodybuilding industry eats 6 times a day and includes carbs such as oatmeal,yams, and brown rice into their diet.
Do you see where I am coming from? I really want to get off the traditonal bodybuilding concepts. The science makes sense but besides a few examples, I don’t see the proof. Help?!
I have the same questions as Jeff S.
I used to be in the Obese category – adopted a bodybuilding lifestlye got down to 9% BF and stayed healthy. I like what IF has to offer and I love the idea of not thinking about food all day but I do get foggy and tired if I go longer than 4-5 hrs without food.
Can someone speak to Jeff S. concerns?
Sorry to point out that the French now have a rising obesity epidemic. In the five years that we have lived here, we are seeing increased obesity on the streets.
This corresponds with the huge updrive of junk food now available…all for convenience…
The original French food pattern in our area was two small meals (breakfast and goute -afternoon tea) and two large meals per day (lunch and dinner).
Is the increased obesity with the “native” French people? Or is it the increased immigrant community to France who are the ones who are obese?
Perhaps I just need to let my body get used to it, but I’m the exact opposite. I’m lethargic until I eat my breakfast, but once I do, I feel a burst of energy.
Also, while trying to gain weight right now, I doubt I could fit 4000 calories into a tiny window of the day, especially while trying to cut carbs. Over half my calories come from carbs: rice, pasta, and oats. My calories would be less than 2000.
Hey Allen. I tried I.F. once back when I ate a “standard” diet, and then recently again after I had adjusted to the primal-type of diet that Mark advocates. I found I.F. MUCH easier when eating very low carbohydrate, because my body was more efficient at using fat (dietary, and in my body) for fuel. I was doing 24 hr cycles (ie: eat dinner, breakfast, lunch, then not eat again till the next dinner).
If your body is expecting to be able to use easily converted carbohydrates, then it’s no wonder you feel lethargic, and then a burst of energy after eating them.
I fall into the same trap of overdoing it on the fruits. Also, I find IF much more manageable when I eat a ‘late lunch’ around 3 or so and then fast through the evening and night. When I wake up the next day I actually am quite energetic and usually do a workout, wait an hour or two and then have a nice big breakfast (late around 10 or 11AM).
“I find that when I fast I am more likely to curl into a ball and do nothing – no energy to do stuff.”
“I gave IF a try once, and all I wanted to do was sleep.”
DITTO
That makes at least three of us.
Me too. It felt like a sick day. Just AWFUL. I’m on board with the science, but in practice I had a hard time with it. I couldn’t wait to get up the next day and eat.
I fast at least once a week (24 hours), or sometimes 2 or 3 times a week.
At first my energy levels were low and I was ravenous when I ate (something I soon discovered you don’t want to do!).
Now after over a month of IF I find I do have more energy like this article indicates. I workout heavy too and love it.
For me, fasting has been the magic bullet to weight loss, more energy, and control over my body. Love it!
Mark,
Today is day 5 of my primal diet program. I have ordered your book on amazon but I have been reading your blog for a while now. Based on that, I have been sticking to a very basic primal diet with no grains. I can tell you that I after my first meal (4 eggs, 1 cucumber, 2 strips of nitrate free bacon, 1 tbsp walnuts and 1tbsp olive oil), I don’t feel hungry till 3-4 pm. Even that hunger is very manageable and I seem to have more energy. During this time (just before meal time, I seem to be more active) My strength seems to have remained the same.
My weight has dropped from 168 to 163 pounds. My ab circumference seems to have remained the same. Can anyone explain this? I definitely don’t want to be losing muscle!
Well, it’s just a thought, but if you just started the diet 5 days ago the weight could be water or glycogen stores. These usually distort weight loss during the first week or two. If your strength is the same, that’s a good sign. Keep your saturated fat intake up, too – just fry those eggs in coconut oil or butter (or bacon drippings). It’s healthy and it tastes great, too.
Thanks. I am eating a decent amount of saturated fats. I guess I’ll see if there is a change in a week or two.
you eating saturated fats are crazy! that’s why you’re the fattest people on earth! Eat tons of palmitic acid which interferes with the feeling of satiety in the hypothalamus and causes insulin resistance. Food manufacturers have known this for a long time and feed you to palmitic acid all day and you eat all day, fast food, butter, milk, sweets and lots more is all full of palmitic acid (palm oil and animal fats) ! I’m not a terrorist, I would like to save millions of people from obesity and premature death that all these related diseases it carries. If you really want to lose weight healthy without starving continues ban oilio the coconut palm oilio and everything it contains, Ninte butter bacon bacon! Eat in the evening at 20:00 and then complete fasting only water until 11-12 days after protein meal with no saturated fat as olive oil, mayonnaise, eggs, fish oil also, light ham, dried fruit but no carbohydrates now! 20:00 to eat more carbohydrates you can. pasta with tomato sauce with Italian olive oil and fried onions found the rivets on the net! pizza bread with lean meat or eggs etc.. then stop until the next day .. 11-12 IF this diet is a cyclic dinner 20:00 – 15 hours fasting – 12:00 Lunch – 8 hours fasting – 20:00 dinner with low saturated fat and low simple sugars.
TRY ONE WEEK, you lose weight without hunger forever is a promise from an Italian friend.
Elizabeth, I’m really impressed with your replies, very much agree with your ideas. been to your website, read all the book you recommend. very impressed!
IF rocks… I can go trough the day without any brain fog, mood swings, sleepiness feeling, even anxiety… My energy is on top and i feel really free..
I think in the psychological aspect the fact you don’t have to put any attention to the eating and post-eating process gives you heap of time to get so many stuff done, it definitely makes my day longer so i can finish everything I’m supposed to.
I always feel more active on fasting days. At times I am almost wired. I think the advice about not missing meals applies to carb hounds only. If you have access to your fat you have the opposite, more active effect.
jeff
Jeff and Jenn,
I eat pretty paleo, do intense lifting/calisthenics and plyometrics twice a week, and sometimes yoga. I’m pretty muscular. I’m 183 lbs and 6 feet. If you click on my profile, you can see my physique.
I used to eat 6 or 7 times a day, but found that I look and feel better eating once or twice a day with high fat meat and leafy greens only. When I was downing smoothies and starches, I was in the 190s and less chiseled-looking as well as always feeling bloated.
I’ve been dabbling with IF ever since I began the PB lifestyle about 8 months ago. It started as a couple of skipped breakfasts to a couple of 24 – 36 hr fasts here and there… It seemed to really spark additional fat loss and I didn’t find it too difficult to do. Then over the past two months, I’ve notice that I just don’t get hungry much anymore for breakfasts,.. and my lunches were getting pushed back further and further to a point that i just wasn’t hungry until about 4-5pm… at which point, i just decided to just wait til dinner around 6-7ish when I got home for dinners… basically i started to follow “just eat when hungry” type of mentality. I realized that I’m able to perform 19-24hour fasts during the weekdays, and eat brunch and dinners during the weekends when I’m with the kids more at home. I’ve felt no noticeable change in energy levels one way or the other… Probably a bit more active when fasted, but I can’t say for certain that it’s really elevated it that much more, as to when I was just eating 2-3 primal meals. I’m still able to work out intensely with weights, sprinting and playing intense sports, and feel pretty good overall. There are some days that I do get hungry around 2pm or if there’s an occasion at the office where people are going out to eat,.. then I just eat. I don’t really force the issue of IF, but it seems perfectly natural to just eat whenever you get hungry. I have noticed that I do feel a bit colder while fasting,..but wearing warmer clothes seems to get rid of that. From what I’ve read, I fast more for the added convenience of not having to eat all the time and the added benefits that come along with it.
I’ve always just eaten one meal a day, really. Big dinner with raw milk and a few egg yolks mixed in with it for breakfast. Since going low carb the thing that is somewhat concerning is how few calories I consume. I’m somewhere around 1500/day and I’m STUFFED.
SENDING A STRANGE WAY SO —LET ME KNOW IF YOU GET IT — OK? IMPORTANT!
I think that when you eat mostly fat, your body gets used to converting its fat stores rather than relying on the constant doses of insulin-spiking carbs. So you can go quite a ways without eating and feel great. I base this on Gary Taube’s book as well as my personal experience. You have to eat this way for a while for your body to learn it. I’ve never purposely fasted; never set out to say “I’m gonna fast today” or “I’m gonna skip this meal.” Usually I am trying to gain weight, as my body does not digest carbs well and I really have no choice but to keep it at about 125 grams per day, almost no grains at all or sugar or dairy, and this level of carbs along with my level of activity makes it a bit hard for me to keep on weight. I eat when I’m hungry. But I’m almost never hungry until I’ve been up and moving for many hours. When I’m engaged in strenuous physical pursuits (mountain bike rides with thousands of feet in elevation gain, rock climbing, hauling heavy packs, etc) I’m often satisfied with just a bite of food here or there…and then I will power down thousands of calories later that evening. Sometimes I’m just not hungry even doing day to day stuff. But I usually end up with about 3,000 calories a day on average, for my 120 lbs 5′ 4 frame. A lot of times I scarf my meals standing up. CW says, very bad! I’ll bet Grok ate this way, and Ms. Grok too. I think this is more natural than 3 meals a day–even though people will treat ya like ur a freak for eating this way! I have no doubt that I can go for a long time on fat stores but sometimes I do wonder about hard anaerobic work when my carbs get low…the burst of power, limit-strength type of work. I think I biff sooner on that sorta stuff when my carbs are low, racing heartbeat and bonk. Muscle glycogen is critical–I’m still tinkering with how much I need and how to get it without my small intestine freaking out. Fat stores are not inert blobs, you know if you’ve read Taubes. Fat is always circulating through your system. Some of us have trained our bodies to use it. Some of us eat pears and oatmeal, and then the body uses those carbs instead and begs for more, stores the extra as fat, which eventually cannot be retrieved when the pancreas tires of squirting out all that insulin, then arteries harden from the excess fat, people are hungry all the time and have no energy. That’s the “too many carbs” negative spiral. PS I love a little bit of steel cut oats once in a while for a special treat, just 1/8 a cup with lots of cream and olive oil and blueberries.
I have been IFing for 2 years now and it is my preferred approach to eating. My wife and I have just built a new house with a long period of moving furniture plus lots of landscaping. We have had plenty of people help out over this time. When a scheduled lunch break or whatever is taken – people have noticed I don’t stop and take a break. My answer – I will go to sleep and lose motivation to keep on moving and working. For me not eating during the day means a full day of endless energy where I can get plenty done. No peaks and valleys – just constant energy. But you can be rest assured that at the end of the day there will be plenty of eating in a primal manner to be done.
I lift weights (intensely) during a 20 hour fasted state all the time… I have never, ever had energy problems. And there’s nothing better in this world than stuffing myself after it. :]
Egads! I’ve did a 24 hour fast last Thursday, IF Sunday 15 hours, and IF for 15.5 hours today. I’ve taken 1 day off from Crossfit. On the fasted days i eat two full meals but am running short of my protein amount, eating 80 to 100g, trying to reach my supposed lean body mass of 138 lbs. I weigh 154lbs.Tonight I did a visual check of my BF. Yikes! I noticed more BF around my waist. Have not gained more than 1 lb. the past 6-7 days. Eating good fats (70-90 grams a day) avocado, nuts, almond butter, olive oil. Consuming good carbs, 99% vegetables…low starch or no starch veggies. Do use olive oil and other dressings on salad. Also, sleeping 6 – 7.5 hours a day.
I am puzzled
?? Thought fasting would help lose unwanted fat and by eating the PB way, would not lose muscle nor energy.
Mark, or anybody else. Do you have an idea how I can reverse the BF increase?
Even though I’m a skinny guy (Octomorph) I still find myself eating sometimes just for the sake of it. I’m gonna skip some snacks today and see how I feel. It’s true about constantly eating not letting our body regenerate itself too.
Here in France, having snacks isn’t part of conventional wisdom. Advertisements for several kinds of non-primal products are even required to warn people against eating between meals.
(Now, not skipping breakfast is part of the local CW).
I am personally used to skipping meals, typically breakfast and/or lunch.
Jeff S and Jenn,
To elaborate more… since eating primally, I’ve leaned out and still stayed muscular. Granted, I’ve lost some mass (probably fat and muscle), but from a purely aesthetic standpoint, everyone has commented that I look better. I know I feel better as for as not feeling bloated when I ate six times a day.
Also, I never really wanted the bodybuilder look and when I was near 200 pounds, I noticed a decrease in my functionality (mobility and flexibility). I still do heavy lifting at times. I switch it up though. I never isolate body parts and always do total body, compound movements. I also use kettlebells and do a lot of body weight moves.
By no means am I skinny-looking. I’m not sure why the paleo/CrossFit adherents you met were “skinny.” Maybe they’re not doing a fair amount of resistance. Did you happen to see them shirtless or in shorts? Maybe they looked “skinny,” but were ripped under their clothing. Seriously.
When I first leaned out from eating strictly paleo and IFing, one of my friends thought I looked “small.” (ironic since I still weighed more than him at 183 to his 170, but I;m more muscular than he is so that makes sense sort of), but then when he saw me changing as we prepared to go for a workout, he remarked that I looked ripped and muscular and very defined. Also, he along with others have remarked that my face now looks more chiseled and my features more defined and masculine (not that they were effeminate before)
All in all, I find that I feel better physically living this why, and that’s what’s most important. When I ate starches dairy and overabundant fruits, I was always hungry yet bloated and felt compelled to eat 6 times or I’d “get skinny.” Still not skinny, but have noticed that my body has dropped superfluous mass. Then again, superfluous is relative. Like I said though, when I start approaching bodybuilding dimensions, I note how mobility and flexibility suffer. I find a I like a balanced state of being aesthetically muscular and lean and svelte, but highly functional. Almost ever bodybuilder I know has zero functionality with their proportions.
Thanks for the detailed reply….it is helpful to hear/see your experience. Jeff S.
Until recently I was a dyed-in-the-wool, dedicated FatBoy. (I’m still fat but every day dawns on less of me.) I worshipped daily at the altars of the great gods of Cheeseburgers, Pizzas, Cookies, and Ice Cream. I state, unequivically, that eating all day definitely slows one down. Eating several small meals does the same thing. As Mark notes, the body has no rest time, it is continually working at digesting the constant influx of food.
I did my first fast almost two years ago. After the initial killer headache which are withdrawal pains, I believe, due to the sudden lack of refined carbs, everything has gone swimmingly. I managed to kickstart my weight-loss and I haven’t had even a single ounce of man-made carbs since. I now do two two-day fasts per month at random times. I always notice an increase in energy during and after the fasts.
My job entails working 24-hour shifts. Usually taking three or four short naps during a shift is no problem but when I anticipate a tough shift with little likelihood of getting a nap or two, I start a fast before the tough shift begins. Staying awake for the 24 hours is still a bit difficult but not any where near as difficult as it would be if I had food in my stomach.
Any time, Jeff. If you do decide to fully jump in, I’d be curious to read how your experience goes. If you continue to do explosive total body movements (lifting, plyometrics, intervals as well as some suspension training with things like TRX, elite rings and straps), I think you won’t get skinny.
Mark’s post fully confirms my experience of the last month. I started IFing somewhat sceptical of my own ability to take to it, and now, four weeks later, I am fasting 23-24 hours every other day. The days when I fast, I have as much if not more energy and clarity than the days when I eat. But unfortunately, you can’t not eat EVERY day…:)
I am sure, based on previous, far more negative experience, that eliminating most cereals from my diet for a month before starting IF helped me adapt to the practice easily. (I still take oatmeal porridge with lots of almond butter and fresh cream on the days I eat, which I guess I must be adapted to, as it gives me perfect bowel movements and leaves me uninterested in sweet foods for the rest of the day).
But the greatest gains for me from IF have been psychological. I realised quite quickly that I just don’t get hungry when I fast, not even after 24 hours (tho anticipation of food will make me look forward to it, physilogically as well as mentally). So for the past 45 years, most of the time, I was eating out of fear of being hungry, rather than from hunger itself. I find it hard to exagerate just how liberating this discovery has been.
Thanks to Mark and all the other people whose exposition of the benefits of IF and the paleo diet helped me realise this before it was too late!
Who really understands the interactions within the human body (transcription factor Foxa2?). It is just far too complex and changing one thing affects many other downstream signalling factors. We do not really know all the compounds in the food we eat, etc.
So many people “sold” on PB use logic. How did we evolve – that makes sense to me. And common sense says if you are active all day (tacking animals for example) – you didn’t take a granola bar with you! And here is another thought – it is 11-am on the West Coast, my 10-year-old has been up for a couple of hours. Is she at all interested in eating yet? Not at all. I think if you just let kids eat when they are hungry many would be surprised at the patterns they would adopt. Most of the way we eat is a learned response.
OK that is my thought – now I have a question for experienced IF’s. Do you have tea or coffee or anything when you skip breakfast? I do find I need a cup of tea (admittedly a learned response – being brought up in England).