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

Why Fast? Part Two – Cancer

cancer“Everyone has a physician inside him or her; we just have to help it in its work. The natural healing force within each one of us is the greatest force in getting well. Our food should be our medicine. Our medicine should be our food. But to eat when you are sick is to feed your sickness.” – Hippocrates

and:

“Instead of using medicine, rather fast a day.” – Plutarch

or even:

“No kibble today, thanks. I’m feeling a bit under the weather.” – Fido

For thousands upon thousands of years (during most of which overweight, let alone obese, people were fairly rare), therapeutic fasting was a common protocol for the healing of many a malady. From famous sages like Plato, Aristotle, and the aforementioned Hippocrates and Plutarch to cancer patients unable to eat during chemotherapy to pet dogs and cats who suddenly lose once-voracious appetites upon falling ill, it seems like the natural response to – and perhaps therapy for – major illness is to stop eating for a while.

Now, “natural” is not always good. “Is” does not necessarily imply “ought.” But I think the persistence of this phenomenon throughout nature demands that we look a little more closely into whether or not there’s something to it. From babies putting items they found on the ground into their mouths to introduce novel bacteria to their bodies, to weight lifters craving meat after a hard workout to introduce protein to their hungry muscles, to pregnant women experiencing strong food aversions to minimize the chance of introducing a toxin or poison to the growing fetus, I’m generally of the opinion that there’s usually a physiological explanation for most of our odd cravings and behaviors. I see no reason why a sudden lack of appetite wouldn’t have a similar explanation – especially one that transcends species. What if skipping meals for a day or two kickstarted internal healing in some way? Is that really so outlandish? You already know where I stand on the importance of lessons learned from watching our animal companions, and I think this time is no different.

Luckily for us, we aren’t just flailing around and making guesses. Modern science has deigned research into the phenomenon, particularly regarding cancer, worth pursuing. According to Valter Longo, a cancer researcher from USC, “normal cells” go into survival mode during starvation. They display “extreme resistance to stresses” until the “lean period” ends, much like an animal in hibernation mode. Cancer cells, on the other hand, are always “on.” Their “goal” is to grow and reproduce and consume resources. For cancer cells, there is no novel survival mode to switch on. If this is the case, fasting should both improve our resistance to cancer and our body’s ability to survive it (and the treatments used against it, like chemotherapy).

Though human trials are scant (you can’t exactly inject people with cancer cells and then try out different therapeutic protocols, the animal research is intriguing. Let’s take a look into the literature, shall we?

Animal Trial

In one of the earliest studies, forty-eight rats were split up into two groups of twenty-four. One group ate ad libitum for a week, while the other group underwent alternate day fasting. After one week of the various dietary protocols, both groups were injected with breast cancer. At nine days post-injection, 16 of 24 fasted rats remained alive, while just five of 24 ad-libitum fed rats lived. At ten days post-injection, only three of the 24 ad libitum-fed rats survived; 12 of the 24 fasted rats remained alive. Pretty large disparity, right?

That was in 1988. It wasn’t until the late 90s that more promising research was undertaken. That’s when Longo began studying in earnest the phenomenon of increased cellular resistance to oxidative stress during fasting. Figuring that since chemotherapy exerts its effects on cancer by inducing oxidative stress (to all cells, not just cancerous ones), and fasting triggers survival mode in normal cells but not cancer cells, he conducted a study on mice to determine whether fasting protected the healthy, normal cells from chemotherapy’s side effects while leaving the cancer cells sensitive to the treatment. Tumor-ridden mice were either fasted or fed normally 48 hours prior to a large dose of chemotherapy. Half of the normally-fed mice died from chemotherapy toxicity, while all of the fasted mice survived (PDF). Furthermore, fasting did not improve the survival rate of cancerous cells, meaning it only protected normal, healthy cells.

Research has continued. Longo found that “starvation-dependent stress” protects normal cells, but not cancer cells, against the effects of chemotherapy. Even a “modified” alternate day fasting regimen, in which mice were given 15% of their normal calories on “fasting” days, reduced proliferation rates of tumor cells. This “85%” fasting regimen was even more effective than the full 100%. And most recently, Longo et al found that fasting both retarded the growth of tumors while sensitizing cancer cells to the effects of chemotherapy – across a wide range of tumor types. Most importantly, they concluded that fasting could “potentially replace or augment” certain existing chemotherapy regimens! That’s not some crazy fad diet guru spouting off about ancient traditional wisdom, folks. That’s a cancer researcher.

Human Trial(s)

There has been just one of which I’m aware: a 2009 case study that delivered promising results. Ten cancer patients – four with breast cancer, two with prostate cancer, one each with ovarian, lung, uterine, and esophageal cancers – underwent fasting prior to and after chemotherapy treatment. Fasting times ranged from 48-140 hours prior to and 5-56 hours after; all were affective at reducing side effects of chemotherapy.

In the first case, a 51-year old woman with breast cancer did her first round of chemotherapy in a fasted state of 140 hours. Other than dry mouth, fatigue, and hiccups, she felt well enough to go to work and resume her normal daily activities. For the subsequent two rounds, she did not fast and instead ate her normal diet, and the side effects were extremely pronounced – severe fatigue, diarrhea, weakness, abdominal pain, nausea – and prevented her from returning to work. For her fourth round of chemotherapy, she fasted, and the side effects were again minimized. And it wasn’t just the subjective effects that improved with fasting, but also her physiological markers. Total white blood cell, absolute neutrophil counts, and platelet counts were all highest after the fasting regimens.

More human trials are underway, however. Hopefully we’ll eventually know whether the loss of appetite commonly reported during chemotherapy treatment is a bug or actually a built-in feature (I’m leaning toward the latter, personally).

Other Possible Protective Mechanisms of Prevention

Improved insulin sensitivity. As I showed in last week’s post on fasting and weight loss, intermittent fasting improves insulin sensitivity and reduces insulin resistance. Insulin resistance has been linked to several cancers, including prostate, breast, and pancreatic. Metabolic syndrome, which fasting seems to help prevent and reduce, is linked to cancer in general.

Autophagy. While autophagy – the process by which cells “clean up” cellular “garbage” – has a complex relationship with cancer, it’s generally a positive process that protects cells from excessive oxidative stress. Fasting has been shown to induce “profound” neuronal autophagy, as well as general autophagy.

Fasting versus caloric restriction.

It’s true that caloric restriction appears to offer anti-cancer benefits, but there are a couple ways in which fasting might be superior:

1. Fasting (acute bouts of caloric restriction) is easier than CR (chronic caloric restriction) for most people. As I mentioned in last week’s post, fasting – for some – is just an easier, more natural, more effortless way to reduce your calorie intake. That can pay huge dividends when it comes to weight loss, and it appears likely that it will help with cancer, too. If fasting is easier than constantly counting your calories, fasting is going to work better.

2. Fasting is more effective in a shorter amount of time. Whereas studies on caloric restriction and cancer employ weeks- and months-long CR regimens, studies on fasting and cancer employ hours- and days-long fasting regimens. In most cases, fasting just seems to require far less time to be effective.

It’s an exciting time for fasting and cancer research. While it’s still viewed in most circles as an “alternative” modality, fasting is now being seriously considered as a possible treatment (both adjunct and even primary) for various cancers, including breast and prostate. I can’t wait to see what comes out in the coming years.

Of course, my own feeling is that fasting is both easier and more effective if you have made the transition to a Primal Blueprint way of eating. In other words, when you have up-regulated those fat-burning systems and down-regulated the reliance on glucose, many of the other issues that can make fasting less appealing to “sugar-burners” tend to go away: cortisol levels out, muscle protein is spared, hunger subsides naturally and energy is steady.

What does this mean for you – the person who either has cancer and wants to get rid of it or who doesn’t have cancer and wants to stay that way? Researchers like Valter Longo can’t officially recommend it to cancer patients, but it seems well-tolerated and basically safe. If you or anyone you know has cancer, suggest fasting as a possible strategy. As long as a person keeps their oncologist apprised of the situation and any relevant research on the subject, it might prove helpful. And if you’re currently cancer-free, consider implementing occasional (intermittent) fasts, just to be safe. I know research like the stuff I’ve just outlined has convinced me that it’s definitely worth a shot, and there’s little if any downside.

For those of you readers who currently practice fasting, do the potential cancer benefits motivate and drive you? If you aren’t currently fasting, does this evidence make you want to? Thanks for reading!

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. http://www.nutritionandmetabolism.com/content/7/1/33

    Metabolic management of glioblastoma multiforme using standard therapy together with a restricted ketogenic diet: Case Report

    This is the first report of confirmed GBM treated with standard therapy together with a restricted ketogenic diet. As rapid regression of GBM is rare in older patients following incomplete surgical resection and standard therapy alone, the response observed in this case could result in part from the action of the calorie restricted ketogenic diet.

    http://onlinelibrary.wiley.com/doi/10.1111/j.1528-1167.2008.01853.x/pdf

    Targeting energy metabolism in brain cancer with calorically restricted ketogenic diets

    Our results in mice with brain tumors together with previous studies in children with malignant astrocytoma indicate that brain tumors are potentially manageable with dietary therapies that lower glucose availability and elevate ketone bodies. These diets target tumor energy
    metabolism and reduce tumor growth through integrated anti-inflammatory, antiangiogenic, and proapoptotic mechanisms of action. While diet therapies are not part of the
    current medical practice in the brain cancer field, we are hopeful that physicians and patients will come to appreciate their value in managing malignant brain tumors.

    http://altcancerweb.com/alternative-cancer/ketogenic/ketogenic-diet-case-reports.pdf

    charles grashow wrote on March 20th, 2012
  2. Hooray! As a melanoma survivor, and someone who wants to stay cancer-free for the rest of my life, I really appreciated this article! I haven’t really implemented fasting in my regular regimen, but when I do feel “off,” the first thing I do is not eat.

    Dawn wrote on March 20th, 2012
  3. My quick question is: has anyone heard of IPT (insulin potentiation therapy). In short, cancer cells feed on gluclose, and are most vulnerable to chemo after feeding and preparing to divide/split into two cells.
    I have read articles with research that IPT before chemo accomplished two things: 1) chemo was much more effective b/c of cancer cells vulnerability while splitting, 2) dosages of half the amount of chemo or less used with IPT were way more effective then full dosages of chemo without IPT.
    I was obviously wondering about the possibility of combining a pre-fast with IPT before chemo to try and incorporate the advantages from both into chemo treatments effectiveness.
    Don’t know if this could work/be helpful, but wanted to roll it out there and see what people thought.

    kip ortiz wrote on March 20th, 2012
    • Yes, have heard of IPT and a carbohydrate restricted or ketogenic high fat & protein diet would be a requisite part of & enhance IPT so as to target and direct the chemotherapy drugs to the cancer cells specifically.

      If there’s anything to the theory at all it’s that IPT works by taking advantage of the fact that cancer cells do in fact have 6 to 10 times more insulin receptors than normal tissues, along with the fact that cancer cells have high glycolytic rates & requirement for sugars due to their use of the glycolysis process for energy production.

      So it wouldn’t make sense to try IPT while maintaining a high carb diet that regularly stimulates lots of insulin production and keeps all of your bodies insulin receptors full of and accustomed to regular deliveries of insulin. The chemo drugs are combined with insulin, NOT glucose or sugars from carbs, so keeping your body in a fat burning ketogenic mode keeps all cells starved of sugars AND all insulin receptors starved of insulin so that upon administration of the insulin /chemo mix hopefully it would go directly to the cancer cells first, or exclusively, because of their higher number of insulin receptors.

      If I was dealing with any serious late stage cancer I would seriously consider IPT a viable option. My studies and research about what cancer is and how it operated has taught me that cancer is orders of magnitude easier to PREVENT than to cure, but in a life or death scenario I personally would not be afraid to pull out all the stops, within reason of course and with my physicians guidance.

      Hope that sheds some light on the issue and helps answer some of your questions.

      cancerclasses wrote on March 20th, 2012
      • …how cancer operates. Damn Auto Correct. :-)

        cancerclasses wrote on March 22nd, 2012
  4. I use modified alternate day fasting combined with a small eating window every day, primarily for weight loss right now, but have come to realize that I am very comfortable with the situation. I eat about 500 cals on low calorie days and 1500-1800 the rest of the time. On the low days, I don’t have anything but coffee and HWC until about 4:00 pm and generally delay eating till 8:00 in the morning or later the next day–about 12-16 hour fasting period every day. I am looking to increase the fasting hours.

    I feel great! I prefer the lower days, honestly. I expect to continue this type of meal “schedule” for the long term. This, combined with healthy Paleo food and movement, is my “retirement fund.”

    hummingbird wrote on March 20th, 2012
  5. interesting post. I recently have started eating less because I just wanted to.

    rik wrote on March 20th, 2012
  6. Feed a cold (ie a virus) and starve a fever (ie a bacterial infection) is an old adage which may be relevant.

    http://www.newscientist.com/article/dn1777-feed-a-cold-starve-a-fever-may-be-right.html

    Not sure where cancer fits into this one – whole different mechanism postulated (not inconsistent thought – just more info)

    Rac wrote on March 20th, 2012
  7. Due to candida, I’ve only been eating about once a day for the last few weeks. I honestly feel great, and figure, if I’m not hungry, and am having issues with digestion, why eat?

    It really does makes sense logically, and it gives your entire body a break. I drink lots of tea (huge yerba mate fan here as well!), and feel great.

    Some days I start to trip out a little, HA! But that’s an added bonus of fasting!

    I’m very happy with the results I’m getting. Less really is more!

    Thank you so much for these latest articles, Mark. They are fascinating!

    pat wrote on March 20th, 2012
    • Like cancers, systemic fungus and fungi in general make energy by using glycolysis, fermentation of sugars. That’s why mushrooms can grow in absolute dark, they don’t use photosynthesis and sunlight to produce energy because most fungus does it’s work of breaking down organic matter underground in the soil and therefore away from direct sunlight. Contrarily that’s why all plants that use photosynthesis die when you restrict or remove them from light.

      Fungi’s use of glycolysis makes them much more similar to mammalian life forms that to plants. Since the human body already has tissues that normally produce energy via glycolysis, both aerobic and anerobic such as in short duration fast twitch muscles, the body doesn’t recognize certain systemic fungus as foreign invaders, and that’s also why systemic fungal infections are so virulent and often extremely hard to eradicate without killing the host human in the process.

      The Phase 1 anti fungal diet as advocated by Doug Kaufmann at Know The Cause dot com consists of a food elimination diet that removes foods that are commonly contaminated by various fungi and mycotoxins, and after eliminatiing those groups of foods you’re pretty much left with a paleo style fresh whole and natural foods diet, and that’s why both the Phase 1 and paleo diets work to eradicate systemin fungi.

      cancerclasses wrote on March 20th, 2012
  8. Interesting, I got breast cancer mid last year, had it cut out and then started eating primal. I declined other treatments and have started fasting until about lunch almost daily. I feel better than I ever have my weight is right down and the cancer is still gone :)

    Stacey wrote on March 20th, 2012
  9. There is a natural cure for cancer that was discovered in 1930. It’s sulfur. I can’t seem to copy and paste the link while on my phone but if you google The Live Blood and Cellular Matrix Study there is a great article on ecognitive about sulfur, it’s role in bringing oxygen into the cells and how cancer is anaerobic. My daughter and I have been primal for two years and have been taking sulfur for over a year. She was autistic but the sulfur helped her to talk again after being nonverbal for nine months. I’m not saying sulfur is a miracle but hot damn that stuff works.

    MamaLovey wrote on March 20th, 2012
  10. We had a really nasty respiratory bug floating around the nursing home I work at about two months ago–half the residents got sick and almost all of the therapy staff contracted it at some point. I did 16-18 hour intermittent fasts during this time and although I did get sick, it only lasted for about 5 days with more mild symptoms, as opposed to everyone else who was sick for 3-4 weeks. Considering I have been very suseptible to respiratory infections in the past, I should have been sick longer than anyone else. I attribute this shortened duration and intensity to fasting and eating Primally.

    fritzy wrote on March 20th, 2012
  11. There’s another quote attributed to Prophet Mohammed: “Fast and be healthy”.

    I have been suffering from psoriasis since the age of 17 (I am now 43). Every Ramadhan when I fast for about 15 hours a day for 30 days straight, my skin clears up remarkably.

    Waleed wrote on March 20th, 2012
    • There’s a newer quote from the prophet Dr. William Davis from wheatbellyblog dot com: “The modern mutant wheat that only grows 2 foot tall ain’t your grandmother’s wheat.”

      And from prophet conrack: “Get a clue, drop wheat & grains totally & permanently from your diet and be done with your suffering from psoriasis once and for all.”

      conrack wrote on March 22nd, 2012
  12. Last time I got a stomach bug (barfing and shitting yourself) I fasted and beat it within 12 hours of experiencing my first symptoms; didn’t eat for two days because my body told me not to, but my energy was perfectly stable until my appetite came back.
    A few co-workers also caught the same bug, none of them recovered any faster than 3 days after experiencing their first symptoms because they kept eating and feeding it, whereas I starved it out and recovered within the first day.
    Cut off the food supply for a bacterium, yeast or whatever it is and soon enough it’ll die off from lack of energy and the competition from your own team of bacteria and immune cells.

    Ross Walline wrote on March 20th, 2012
  13. Fasting is a great tool to health. Everyone should at least read up on it if they haven’t yet.

    Now for a little math: If one was to fast one day every week, then that would be 52 days a year. That is almost two full months of not eating.

    If nothing else, it’s a great way to save money! But it is so much more!

    Gabor wrote on March 21st, 2012
  14. I fasted at true north heath center in california..I felt a lot better.I am sure it will clean you body of toxins so that they won’t react further and cause cancer later

    rachel wrote on March 21st, 2012
  15. I drink Yerba Mate every working morning. Oftentimes I do not have any breakfast, which effectively means a 14 hour period without munching anything.

    Does this count as fasting?

    Álvaro wrote on March 21st, 2012
  16. I have chronic myeloid leukemia,CML. I was eating “mostly” paleo before diagnosis in July but more strict now. I don’t do chemotherapy but take an oral cancer drug once a day. I love this article but wonder how it would work on a blood cancer. When we start our cancer drugs the Stem cell that caused our cancer goes into hiding and hibernation. We can be PCRu, leukemic cells undetected in a sample of blood, but we are never in remission or cured. That stem cell is still hiding in there somewhere.

    Kim wrote on March 21st, 2012
  17. love all the comments and totally agree that on fasting days I feel full of life and joy and razor sharp
    if I get tempted to eat something its only because of my mind talk – the body and soul doing just fine
    so it is best for me to stay away from the kitchen
    thank you all for the encouraging messages here, so great to know Iam not alone-fast day today!

    AniaMaya wrote on March 21st, 2012
  18. Well this is very interesting. I had being trying to lose weight for months late last year and was pretty much on a low GI diet but wasn’t really shifting the weight like 3 yrs before. It was very upsetting and confusing. I was 100% PRIMAL back when it fell off, age 49 at a rate of 1 kg a week. Now I am menopausal, not sleeping, stressed and only just getting some walking and primal exercise back into my life. I realised after discovering this place that I was not 100% Primal this time around. Also pretty much sedentary for the past 2 yrs no longer walking 35min each day before dinner due to my new office job and weird working hours.
    Looking back 3 yrs ago, I remember how effortless primal eating had been and how I lost interest in carbs to the point that not one touched my lips in 12 weeks. Wow. now I know why.

    I have been Consciously Primal since early Jan when I discovered this wonderful place in my frustrated attempts to understand what was stopping me from losing weight this time around. Watching my family dropping about 5 kg in 7 weeks whilst I lost only a 2 and then hit a plateau was tough.
    Recently I wanted to find out more about the hard science behind weight loss and i have just read Primal Blueprint plus Good calories Bad calories and Why we get fat by Gary Taubes. Wow that satisfied my need to know the details.
    Sleeping is a major problem. I am taking valerian and magnesium complex and woke up twice last night instead of every 90 minutes. Here’s hoping the Valerian will help me out of this 2 yr horrendous sleeping pattern. I’ll keep you posted.

    So here’s the thing. I read about fasting here and I became a little worried that if i fasted i would ruin everything by slowing my metabolism down and needing even less primal calories to sustain my weary menopausal bod. I managed an easy 24hr fast last week and was thinking of stepping it up to 7 day fast. I am no stranger to fasting. I did religious fasts as a kid, about 3, 7 day juice fasts in my 20’s and about 3 in my early 40’s losing around 9 lbs each time. Living in Eygpt in my 31st year I tried a 30 day Ramadan fast and ended up doing 4 in the following years. What really surprised me about Ramadan was that i thought i couldn’t do a 16 hr water and food fast because i had lots of issues with blood sugar and hypoglycemia but actually even though i ate carbs in those days, my blood sugar settled down during the fasting month to my absolute surprise. Now that i have ready Gary’s books and loads of articles here I realise that its been insulin all along. Stop the flow of insulin and i turn into a happy chappy.

    Do you think it would be unwise for me in particular to do a long fast to kick start the fat burning and keep it going?? Could it mess things up and cause my body to hang onto more fat since I am sleep deprived and not functioning metabolically like most other folks.. I really want to lose weight… help!!!!

    Maryam wrote on March 21st, 2012
  19. Anyone have any experience on fasting results for “hard gainers” like myself? I’m 6’5″ and 170lbs, skinny as a rail. I went primal a few months ago and love it for the usual reasons, energy, no shakiness when I miss a meal, hunger management, less muscle soreness after workouts. But I am someone who has to work ridiculously hard to PUT ON weight. So would IF have any benefits for me?

    Brian wrote on March 21st, 2012
  20. Mark–nothing to add to your points. It’s hard to find a reason NOT to fast. A lot of my family are naysaysers. Pity that the “breakfast is the most important meal” and “several small meals” has been pushed so heavily that people can’t consider fasting.

    Here is a quote from Mark Twain that I think applies to your post:

    “A little starvation can really do more for the average sick man than can the best medicines and the best doctors. I do not mean a restricted diet; I mean total abstinence from food for one or two days. I speak from experience; starvation has been my cold and fever doctor for 15 years, and has accomplished a cure in all instances”.

    Daniel Wallen wrote on March 21st, 2012
  21. haha I on the leangain fasting. It great to know that marks in to fasting to. And if people think you lose muscle check out the web site leangains.

    matthew wrote on March 22nd, 2012
  22. anyone breastfeed and fast? i don’t want to ruin my milk supply or get mastitis.

    diane wrote on March 22nd, 2012
  23. Mark, I began incorporating intermittent fasting into my life in January of this year as a way to lean out and jump start weight loss after gaining a few holiday pounds. I fasted for 16 hours each day following the guidance at leangains.com. I wrote 3 blogs about the “experiment” as I called it on my blog. http://www.summer-smith.com. The experiment was so successful and I felt so great that I have continued to follow the plan 5 to 6 days per week. I am an avid believer in this practice and want to find ways to incorporate periodic, longer fasts. Great write up on the benefits of IF as it relates to cancer treatment. If it can do that for cancer treatment, imagine the benefits of IF for cancer prevention!

    Summer Smith wrote on March 22nd, 2012
  24. For some reason my comment didn’t post, so I will remove all the links — maybe that was the problem? — anyhow…

    What I have found on fasting and/or caloric intake restriction agrees with your’ research, here, Mark, but you missed a thing or too (see entry #9 at bottom), and while my research showed affects on life-span, I infer that anti-cancer benefits also emerge:

    (#1.) “These results suggest that total caloric intake may modulate the rates of cell death and proliferation in a direction consistent with a cancer-protective effect in DR mice and a cancer-promoting effect in AL mice.”

    (#2.) “9. Weindruch, R. and Sohal, R. S. (1997) Caloric intake and aging. N. Engl. J. Med. 337, 986-994.”

    (#3.) “13.Dhahbi, J.M., Tillman, J.B., Cao, S., Mote, P,L., Walford, R.L., and Spindler, S.R.: Caloric intake alters the efficiency of catalase mRNA translation in the liver of old female mice. J. Gerontol. 53A: B180-185, 1998.”

    (#4.) “A UCR researcher finds a connection between decreased caloric intake and increased life span.”

    (#5.) “We have known for many years that reduction of caloric intake by up to 40% over that of the normally fed diet, while also maintaining essential nutrients and avoiding malnutrition, is the only intervention that will extend the maximum life span of animals from many different genera.”

    (#6.) “Caloric Restriction, or reducing the caloric intake by 30 to 50 percent, has increased both the average and maximum lifespan in rats and mice more than 30 percent. The animals receive enough nutrients but weigh considerably less than their non-restricted counterparts. Studies have also shown that the rodents are healthier, with lower blood pressure and a postponement of age-related declines in muscle mass, immunity and other areas.”

    (#7.) “Recent Research Shows Lower Calorie Diets are Associated with Longer Life”

    (#8.) “Harman: It was first shown in the mid-1930s that reducing caloric intake would increase both the average and maximum life spans and decrease disease incidence. I believe that this result was due to decreased free radical damage owing to decreased oxygen utilization. Glycosylation may play a minor role in this effect as glucose levels go down when calories are restricted.”

    (#9) Researcher, Gordon Wayne Watts, BS Biological and Chemical Sciences (FSU, 2000) thinks that the reason reducing caloric intake helps increase life span is quite simple: When the human body is not overloaded with food, it can more easily get rid of bodily waste products –and thus, we have the body’s cells able to reproduce and heal in a cleaner chemical environment.

    Gordon Wayne Watts wrote on March 22nd, 2012
  25. Ok, inspired by Mark’s post I did a 2 day fast. I only drank green or black tea without anything but water. I lost two pounds. I am a very stubborn weight loser (down to those A receptors I guess) so this was fun to see. It was quite easy actually and I am thinking of doing it bi-monthly. Not sure if this is typical protocal however I broke my fast with a Scotch whiskey. I highly recommend not eating for 48 hours then having a shot of whiskey and waiting about 15 minutes. It was a wonderful buzz. It also seemed to take a bit off the need to devour that first meal. For my breaking-the-fast meal I had a nice big salad, some squash with butter and a half rack of ribs and I was full. When I woke up in the morning the 2 pounds I lost were still lost. (I hope I never find them) I broke my fast while watching “Gandhi” which, even though he’s one of my true inspirations, gave me some strange perverse and ironic joy, especially since I broke my fast eating ribs.

    David Cole wrote on March 23rd, 2012
  26. Thank you so much for the very illuminating post Mark.

    After reading your post and the numerous ensuing comments, I’m starting to wonder whether we should put all the different kinds of intermittent fasting into the same category –“IF”. I’m not quite sure that a fast lasting several days (even 24hrs) has the same effect on the body as a fast done for 10hrs only within the day. I guess fasting for several days is something one can do occasionally, whereas fasting for 8-10hrs is something that can be done everyday.

    For instance, I’m used to fast from the early morning till the evening, and have my main (unlimited ;-) ) meal of the day at dinner. That’s my routine and I’ve been following it naturally (without any pain) for years. Actually I feel stronger and more productive during the day when I’m fasting. However I’ve never tried any form of long fasting, and I can imagine my body may react differently to it.

    I would be very interested in knowing whether the effects of both kinds of IF are comparable (in terms of all the advantages mentioned concerning the metabolism etc.)

    Thanks in advance for your insights!

    Lemurette wrote on March 24th, 2012
  27. I’ve always been of the mind not to eat, or majorly restrict consumption, while ill. I don’t currently make intermittent fasting a habit, but this has given me a lot to consider about it. I may also discuss it with a friend who is about to undergo chemotherapy treatments, although he’s not primal, very conventional wisdom, so I’m not sure how far that will get.

    Jody Ruttan wrote on March 24th, 2012
  28. I had read Mark’s first article about fasting and was floored. It really was ok to skip a meal if I was not hungry!
    Since that day I have only eaten one meal a day…happily!
    What freedom!
    I have a nice new clarity of mind, I have slept like a champ, and I feel so good inside.
    Now to read this might help keep me from cancer…bonus!!
    I have so much to thank Mark for…we all do…
    Please keep up the good research for us.
    I appreciate you and your work.

    Sarah Martini wrote on March 27th, 2012
  29. Is fasting a big no no while breast feeding?

    Heidi wrote on March 28th, 2012
  30. Mark,

    Good read, thank you! I’ll be forwarding this to my brother-in-law, his mom has breast cancer. I try and fast twice a week, one shorter, say around 12-16 hours and one dedicated full 24 hour fast a week. I do my 24 hour fast on my recovery day so my training doesn’t suffer. Just got done reading “Primal body primal mind” by Nora Gedgaudas, she’s got some good info on fasting and the positive physiological effects of it.

    Looking forward to your next post!

    Tyler,

    Tyler Holt wrote on March 29th, 2012
  31. Does anyone think fasting might help the auto immune condition scleroderma?

    Irene wrote on April 18th, 2012
  32. With three generations of cancer occurrences (some minor, others severe)in my lineage, I am more aware of the nature of the impact than some of my peers. Fasting, for me, has previously only been about sleeping through part of it and then skipping breakfast and lunch. I am at a plateau with fat loss at the moment, so I’ll step up and add another meal… er.. subtract one more and see… I love this site so much. I can honestly say it changed my life in the last 6 months.

    Jack wrote on April 25th, 2012
  33. Hi all! I would like to add an appendix to Mark’s notes about who shouldn’t be fasting. I’ve done a fair bit of research into the neurobiology of fasting, and I’ve posted a summary of it, titoled Hypocretin Neurons: The Link Between Fasting, Stress, and Arousal, or, Why Fasting Breeds Insomniacs, here: http://www.paleoforwomen.com/hypocretin-neurons-the-link-between-fasting-stress-and-arousal-or-why-fasting-breeds-insomniacs/

    Not self promoting, just wanting to get the news out there. Fasting goes wrong for many people, and I think its helpful for them to understand why

    Stefani wrote on April 30th, 2012
  34. What is your definition of fasting? Just water?
    Just Breath?
    Low Calorie? How much calories is a fast?

    Thanks,
    Dan

    Dan Hegerich wrote on April 30th, 2012
  35. I enjoyed reading your site, and just wanted to pay you a compliment: You’re a pretty good writer.

    J wrote on May 15th, 2012
  36. Thank you for taking the time to make this article. As a Muslim what I want to say is: Just be Muslim. It is mandatory in Islam (except for women with menses, children, and for those who can fast with difficulty, ex:old man) to fast from sunrise to sunset for a period of a month (Ramadan).

    Additionally, it is advised in this religion to fast Mondays and Thursdays.

    Thank you for your article.

    Tik wrote on May 27th, 2012
  37. I drink a liter of yerba mate every morning using this gear:

    http://upload.wikimedia.org/wikipedia/commons/b/bc/Mate_05.jpg

    I find it stimulating, just like coffe. And it lasts me hours and keeps me company while I desk-jockey at work.

    Alvaro Coronel wrote on July 29th, 2012
  38. I actually have stage 4 breast cancer and have had incredibly good results lately following a paleo diet and supplement program designed by my holistic doctor (as well as with chemo and radiation.) For the first time in a year in a half, my scans have come back with results of all the lesions in my lungs and liver shrinking considerably. I have just taken up intermittent fasting as of yesterday because I have read about it’s effectiveness when used in conjunction with chemotherapy. I have treatment tomorrow morning and I plan on fasting from 9pm to 1pm. I’ve done it the past two days with no ill side effects, in fact, I feel great while fasting… very focused and alert!

    Lillian Davenport wrote on August 16th, 2012
  39. I have had ulcerative colitis for over 20 years. Even before that I had happended to read a book called something like “Triumph Over Disease by Fasting and Natural Diet” by Jack Goldstein (written in 1970’s). It basically outlined his personal experience of being cured of colon disease when he was at the point of death through a pronglonged (42 day!) fast at a fasting and healing center. I kept this in my mind but never fasted for more than the occasional day, UNTIL a colonoscopy revealed to me that I *might* have colon cancer 2 years ago. My gastroenteroligist wanted me to have my colon taken out, but first he scheduled a second colonscopy where he was going to take many more tissue samples from my colon. The shock of possible cancer woke me up and I immediately fasted (while continuing to work) for about 9 days, followed by intermittent fasting for 3 more weeks. I probably consumed nor more than 5 “regular” days of food in 30 days. At the second colonoscopy the doctor took over 100 biopsies, none of which tested positive for cancer or even “pre-cancerous”. Did the fasting help? I am not sure. I have fasted the occasional day or two since then, with 5-6 days max, but sometimes find it hard to start these now because I keep thinking i really need to fast to “weeks”. I sometimes eat well, sometimes bad for stretches. 2 years later I need to go back in for another colonoscopy. I know if it finds any cancer I will turn to fasting before or in addition to any chemotherapy treatments.

    Mark wrote on September 27th, 2012
  40. Wow, just wow, fasting just keep on rolling out the benefits! My husband and I just started the fasting lifestyle (one meal a day). We have our reasons for fasting, mine was originally only to lose some weight, but as time goes by and after all the information I have read here and on other sites, I really feel so committed to this lifestyle for so many more reasons. It just simply makes sense to me.

    The cancer research is so interesting to me and obviously wonderful. We were just discussing cancer yesterday, because so many of your friend’s parents are finding out that they have cancer and basically, it’s just really scary. I almost feel that nowadays you are lucky if you don’t get cancer. My only problem is this; people are suborn, they have been told all their lives that ‘not eating=bad’, how on earth do you convince the people you love to change their mind set about food? We basically keep our eating habits a secret at this time, I tried to tell one of my friends what we are doing, but my word fell on deaf ears once I mentioned that we were only eating once a day!

    Willow wrote on October 3rd, 2012

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