Part 4: What Happens To Your Body When You Fast? – Healing and Longevity
Here we are at the fourth installment of our look at the physiology of fasting. Thus far, we’ve looked at energy production, hormonal effects, the anti-inflammatory nature of fasting, and changes in blood markers. Today, let’s look at healing, disease, aging, and longevity.
Disease
Let’s start with disease. We’ll start with The Big C, cancer, the second-leading cause of death in the United States. All of the studies I found were in rats and mice, but we have to remember that IF is still an emerging science. In our rodent friends, cell proliferation rates are lowered by 25% caloric restriction, but not as much as by Alternate Day Fasting. A report on another study showed that a 5% reduction in calories, but only being fed every other day, also reduced cell proliferation rates.
And if you’re unfortunate enough to have a case of cancer, a 48-hour fast prior to chemotherapy can help normal cells express protective mechanisms, limiting the therapeutic damage to the cancerous cells. In fact, in mice the effect was to make normal cells 5-10 times more resistant than cancerous cells to chemo. Unfortunately, human studies are lacking, but again, we’re dealing with emerging science.
Since we’ve looked at the second-leading cause of death, we might as well take a gander at the leading cause, heart disease, where there is a bit of data on humans. HDL and homocysteine levels improved in healthy 21-35 year old volunteers fasted on a Ramadan-like schedule. Animal research shows other intriguing data. Rats fasted intermittently have shown a propensity to lower a heart rate and blood pressure. Beyond the beneficial cardiovascular effects, the researchers noted that the IF rats had an improved neuroendocine stress response.
A study that I commented on in the last post also has implications here. Three doctors have found that using a protocol of eating 20-50% of their normal caloric intake one day and ad-lib eating the next (Alternate Day Caloric Restriction) resulted in improvements in numerous health problems, such as “asthma, seasonal allergies, infectious diseases of viral, bacterial and fungal origin (viral URI, recurrent bacterial tonsillitis, chronic sinusitis, periodontal disease), autoimmune disorder (rheumatoid arthritis), osteoarthritis”. I’ve noticed similar effects in that fasting seems to help me get over anything that tries to get a hold of me.
And while we’re talking about disease, Intermittent Fasting also has effects on Huntington’s Disease, a genetic condition characterized by lack of coordination and effects on some mental abilities and behaviors. While this was tested in mice, humans and this breed of mice exhibit the same Huntington gene, an interesting fact. These mice saw a delayed onset of the disease symptoms along with improved longevity. There is a fasting-induced increase in brain-derived neurotrophic factor, discussed below, and in a specific heat-shock protein that are hypothesized to be the contributing factors. As you’ll recall from my second post in this series, heat-shock proteins help ensure that proteins maintain their proper form.
Healing
Unfortunately, I couldn’t find anything on healing of wounds such as fractures or cuts. But, in my mind, more important than healing from a broken arm faster or reducing muscle soreness to allow for another hard workout, is protecting the brain. Scientists at the University of Kentucky found that “fasting for 24 hr confers neuroprotection, maintains cognitive function, and improves mitochondrial function after moderate (1.5 mm) TBI [traumatic brain injury].” So fasting does definitely promote a healing effect in the body, though there’s no telling if it carries through to other areas (I’m betting it does). Interestingly, one symptom of a concussion is a decreased appetite. Could the body be telling us something?
Aging and Longevity
One purported benefit of fasting is an increase in longevity. But living longer isn’t all that fun if your body is giving out. You want to age well, not just age. One of the keys to aging well is maintaining your brain function at a high level. As luck would have it, intermittent fasting protects brain neurons from excitotoxic stressors. That means your brain is more resistant to injury. While that abstract doesn’t report what the Intermittent Fasting protocol was, it does specifically say “Intermittent Fasting”.
It also looks like fasting increases levels of brain-derived neurotrophic factor (BDNF), a substance that increases the growth of brain nerve cells. This stuff is also “neuroprotective against stress and toxic insults to the brain and is somehow’no one yet knows how, exactly’involved in the insulin sensitivity/glucose regulating mechanism.”
Both caloric restriction and Intermittent Fasting have shown promise in protecting the brain from the damages that seem to come with age and contribute to diseases like Alzheimer’s and Parkinson’s. The fasting protocol activates “FoxO transcription factors, sirtuins and peroxisome proliferator-activated receptors [PPARs].” FoxO transcription factors are part of a family of proteins that regulate cell growth and longevity. Sirtuins manage cellular regulation. And PPARs regulate gene expression, growth, and metabolism.
Art DeVany had an interesting post on autophagy, or “self-eating,” some time ago. Essentially, when the cell is depleted of energy, it turns to its own damaged proteins for energy, effectively using old worn out pieces to repair itself. Constant overconsumption down-regulates cellular repair, obviously not good for longevity. But as we saw in the first piece, by forcing the body to find ways other than incoming food to provide for energy needs, fasting depletes cells of energy.
Chris at Conditioning Research had a post titled Intermittent Fasting for Longevity. The key mechanism here is the expression of a hormone called FGF21 (fibroblast growth factor 21) that inhibits the actions of growth hormone, slowing aging. It all pieces together very nice between the body suppressing excessive growth, consuming worn out building blocks, and growing new pieces to replace the old.
Wrapping Up
Well, I think four short books is enough of a look at the science behind Intermittent Fasting. Sorry for getting all technical there at the end with FoxOs and sirtuins, but I’m learning as I go here and find this stuff fascinating. In the next post, I’m going to touch quickly on exercising while fasted, then I’m going to do a Q&A post to close it out. If you have any questions, stick ‘em in the comments!
About Scott
Scott Kustes loves to cook and loves to eat. He started Real Food University to help you get maximum enjoyment out of the meals that you eat. To find out more about how he has rebelled against the fast food culture and counting calories or carbs, join the Real Food Revolution.
13 Reader Comments
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Scott – do you ever fast overnight? (i.e. for more than 24 hours?) I regularly drop in a 20 – 22 hour fast which I break with an evening meal, but cannot imagine going to bed hungry. Even if I have a smaller-than-usual meal in the evening I sometimes wake up at 5am thinking about food
The part on cancer seems to make sense as I think about it. From a paleo standpoint, grok probably didn’t have the resources to gorge himself with food all the time, so if we assume thats our “blueprint” (per MDA), then yeah, having a high calorie diet (even if you burn a lot of it) might definitely have some cancerous implications down the road… interesting stuff.
Hey Scott,
Way to go with this… you definitely went above and beyond.
Quick question though. Did you ever experiment with fasting during your endurance/weight training?
I don’t know what it is, but I can’t picture working out strenuously (either with weights, running, or otherwise) without having eaten for 12-18 hours. Is it something the body acclimatizes to over time?
Once again, great job, very informative.
-becomingadonis.blogspot.com
Steve,
I bet Scott will comment, but I figured I would throw my two cents in about going into a workout in a fasted state. I actually have more energy when I go into a workout in a fasted state. I like to have a big cup of black coffee -or- 3-4 cups of green tea 30 minutes before hitting the gym.
For some reason the caffeine really seems to “kick in” much better when no food is present. I like to lift for 30 minutes, followed by Interval training for 15 minutes and then 20 minutes of steady state cardio.
When you are fasted for 18-24 hours the body really seems to switch over to burning fat for energy. Add an intense brief workout and you are golden. I swear I feel much leaner after an 18 hour fast followed by a solid workout.
One more thing…If you look in the upper left hand corner of Scott’s site, there is a banner of “Eat Stop Eat”…click this banner and opt in to Brad Pilon’s free newsletter. It will give you even more info on Intermittent Fasting.
The cool thing about Eat Stop Eat is that it is basically a summary of Brad Pilon’s college graduate study. This is exactly what Brad focused on in college. I don’t recommend many ebooks on my site, but this is one that I recommend without hesitation.
Scott has certainly overdelivered on his course on this blog. Quit it Scott! I speak for all of the fitness bloggers…you are setting the bar too high here!
I’m kidding…Keep it up buddy!
Methuselah, the closest to fasting overnight I ever came was when I experimented with 24-on, 24-off and that was ending my eating at 6pm. I wouldn’t really count that. I don’t like going to bed hungry, so it’s not in my near future.
steveSCENE, I typically workout fasted, especially if it’s strength-oriented. When I was in training for the track meet a few months ago, I was breaking the fast about 2 hours before my workout with a bit of fruit, a hardboiled egg or two, and some nuts just to make sure I was well-fueled. I’ve not noticed any issues with metcon workouts. Makes sense as the muscles should be fueled enough for a short burst even after an 18-hour fast. Prolonged intense workouts may require a bit of intake beforehand, but I’d see how performance is fasted before making that call.
Rusty, thanks for the kudos! I also like the pre-workout coffee. In fact, I used that little trick before my sprints at the Bluegrass State Games. Caffeine about 30-60 minutes before a workout seems to kick things up a notch.
Cheers
Scott
This is a really great series and made me realize so much about IF and why I do it…..As for coffee I have decided to drop it from mornings I am IFing as I feel it gives me a tad too much anxiety later in the day, this did not used to be the case but after months of doing it I am guessing it has taken its toll on my body. I have switched to herbal tea’s during fasts and then I have coffee with meals (mainly because I love the stuff)
I really appreciate the work that must have gone into this series, great posts!!
Autophagy is an interesting process science is just beginning to understand the importance of. It might be the reason why you see CR/IF giving increased longevity (enabling better cell health and tumor prevention), but can also be a double edge sword for people that already have cancer, as you don’t want the cancer cells to repair themselves…you want them to die off. Cancer research is looking into how they can possibly turn on and off autophagy for treatment. Should be lots of new good research on that soon. Here’s a quick sample of what I found on it:
“In conclusion, we now have good reasons to think that manipulation of autophagy may provide a useful way to prevent cancer development, limit tumor progression, and increase the efficacy of cancer treatments. This goal seems reasonable because we have drugs that induce autophagy, such as rapamycin, and are rapidly gaining a better understanding of how this process works by studying the effects of targeted inactivation of autophagy regulators in mouse models and human tumor cells. However, the question of whether we should try to switch autophagy on or off is not straightforward; sometimes, we will want to increase autophagy, whereas at other times we may want to reduce it. Therefore, unlike some other aspects of tumor cell biology, such as cell growth, apoptosis, or angiogenesis, where we always know how we would like to manipulate the process in the tumor (less, more, and less, respectively), our goals for manipulation of autophagy will likely be context dependent ”
taken from http://cancerres.aacrjournals.org/cgi/content/full/66/19/9349
[...] – bookmarked by 6 members originally found by deewt on 2008-10-30 Part 4: What Happens To Your Body When You Fast? – Healing and Longevity [...]
‘Chris at Conditioning Research had a post titled Intermittent Fasting for Longevity. The key mechanism here is the expression of a hormone called FGF21 (fibroblast growth factor 21) that inhibits the actions of growth hormone, slowing aging. It all pieces together very nice between the body suppressing excessive growth, consuming worn out building blocks, and growing new pieces to replace the old.’
I’m a little confused about this, I thought that I.F. promotes higher HG levels, and it was HG levels that inihibited aging. Brad Pilon writes of this repeatedly on his blog and book. I am misunderstanding this?
I wasn’t sure how else to get this link to you, very interesting article from 1937 about how eating too much, too often, leads you to commit a slow suicide.
http://blog.modernmechanix.com/2009/04/09/people-dont-die-they-commit-suicide/?Qwd=./PhysicalCulture/1-1937/people_dont_die&Qif=people_dont_die_0.jpg&Qiv=thumbs&Qis=XL#qdig
Thought you might like to read
Diana
Fasting is a ancient remedy that is a new revelation to the modern medical industry that promotes the healing of self. The fact that a bandaid type of philosophy which is geared towards repair, or damage control, and not preventitive maintenance or actual healing, is to the benefit of all of the multi-billion dollar pharmacuetical and health insurance companies. Most all medical scientist know this but will not advocate the practice of such said fasting. Why? The truth is, what need is there for the over abundance of doctors and usage of drugs if humanity possesses the knowledge and the power to heal itself though the simple process of fasting? It is the profiting by merchants who promote illness, sickness, and ultimately death.
Fasting is the number one most effective way to cure 90% of what most often plagues our health and cuts our longevity as human beings. From most minor aches and pains due to the aging process to life threatening diseases can be virtually eliminated just by cutting down the number of meals ingested in a 24- hour period from 3 to 5 meals per day, to just one meal per day. Just the mere fact that the stomach can not be replaced and should be allowed to rest just like any other part of the anatomy simply makes sense. The electromagnetic vibrational field of the body at micro-atomic cellular level is accelerated which causes the body to repair, renew and heal itself whenever the body goes beyond a 24 hour fasted state. A fast for 72 hours once per month brings about miraculous results for anyone desiring to elevate the quality of life while reducing medical bills. Fasting in the prescribed manner is with out question the best medical insurance one can have without costing a small fortune.
Hi Scott!! Ma name is FREDY JOSEPH an MD student at MUHIMBILI UNIVERSITY OF HEALTH AND ALLIED SCIENCES. I am a Christian and I am saved! I have found your topic very very interesting! the time i found it, I mean today 30th July 2010 is my 3rd day fasting without taking anything! Anything even water! the last time I ate was on Tuesday 27th JULY 2010 at about 10;00pm. Thus my fasting period is about 72 hours! am expecting to eat at 10;00pm today! surprisingly I am continuing with my studies and other activities as normal up to now! Spiritually I believe that GOD gives us extra strength when WE fast for prayers! I have gained more knowledge from your site and I promise to teach others about the advantages of fasting!
When
When I was in form six I was doing my exams while fasting and i was doing very well!