This past weekend was the Jewish holiday of Yom Kippur. On this day, Jews around the world (and their doting husbands, apparently) do not eat from sun down to sun down, and reflect on their misdeeds of the previous year and how they can better themselves.
The effects of fasting has many purposes. For the very religious, the belief is that the spirit–the life force that animates the physical body–is forced to be uncomfortable as it’s “home” suffers. For the not-so religious, such as me and my husband, the mental and emotional blunting that comes along with fasting serves as an official time to reflect and be in a semi-meditative state for much longer than is usually possible. We have made it our “family” custom to spend this time together, really appreciate each other as people, and talk out any problems that may have been festering throughout the year.
And for everyone, the effects fasting has on blood sugar, insulin sensitivity, and disease prevention can be interesting, to say the least.
“Eat like a lion”
That quote seems to be fairly popular within the intermittent fasting(IF) community, and it’s not hard to see why. Our ability as humans to run long distances serves as proof that we were, for a long time, a persistence hunting species (we actually still are in some parts of the world).
If you’re interested in learning more about our long distances abilities, this is a great talk to watch:
The major take-away quotes from this video that relate to fasting are:
“Two million years ago the human brain exploded in size. Australopithecus had a tiny little pea brain. Suddenly humans show up — Homo erectus — big, old melon-head. To have a brain of that size, you need to have a source of condensed caloric energy. In other words, early humans are eating dead animals — no argument, that’s a fact. The only problem is, the first edged weapons only appeared about 200,000 years ago. So, somehow, for nearly two million years, we are killing animals without any weapons. Now, we’re not using our strength because we are the biggest sissies in the jungle. Every other animal is stronger than we are — they have fangs, they have claws, they have nimbleness, they have speed. We think Usain Bolt is fast. Usain Bolt can get his ass kicked by a squirrel.”
“Maybe we evolved as a hunting pack animal. Because the one advantage we have in the wilderness — again, it’s not our fangs and our claws and our speed — the only thing we do really, really well is sweat. We’re really good at being sweaty and smelly. Better than any other mammal on Earth, we can sweat really well. But the advantage of that little bit of social discomfort is the fact that, when it comes to running under hot heat for long distances, we’re superb, we’re the best on the planet. You take a horse on a hot day, and after about five or six miles, that horse has a choice. It’s either going to breathe or it’s going to cool off, but it ain’t doing both — we can. So what if we evolved as hunting pack animals? What if the only natural advantage we had in the world was the fact that we could get together as a group, go out there on that African Savannah, pick out an antelope and go out as a pack and run that thing to death? That’s all we could do. We could run really far on a hot day.”
It can be logically argued that it is not natural for us to eat 3 small meals and snacks a day. This is the foundation for the theory of intermittent fasting as a whole.
What is Intermittent Fasting?
IF is the practice of fasting for a period of 10+ hours.
The most popular options are not eating for 14-16 hours every day, and having a “window” of allowed caloric intake, or fasting completely for 24 hours, twice a week, with normal intake the other 5 days.
Brad Pilon explains it best here:
Benefits to IF
There is evidence that regular fasting for short amounts of time (under 48 hours) has a similar effect on the body as regular exercise on both heart and brain function and disease resistence, though there are still some unknowns. Multiple studies have found implications that fasting regularly can reduce the risk for disease, even in those genetically prone:
“After 3 months of IF or regular every-day feeding (control) diets started in 2-month-old rats, myocardial infarction (MI) was induced by coronary artery ligation [tying]. Twenty-four hours after MI, its size in the IF group was 2-fold smaller, the number of apoptotic myocytes in the area at risk was 4-fold less, and the inflammatory response was significantly reduced compared with the control diet group. ”— Cardioprotection by Intermittent Fasting in Rats
Ismayil Ahmet, MD, PhD; Ruiqian Wan, PhD; Mark P. Mattson, PhD; Edward G. Lakatta, MD; Mark Talan, MD, PhD Available here: http://circ.ahajournals.org/content/112/20/3115.long
Essentially the findings of that study are that rodents kept on an IF schedule suffered less cell death, and repaired more efficiently from the injury of having one of the valves in their heart tied closed (as close as researchers could get to mimicking a heart attack).
There are some studies that also suggest IF could have a hand in preventing Alheimer’s and Parkinson’s disease when started by middle age or sooner:
“IF may therefore protect neurons against adverse effects of Aβ and tau pathologies on synaptic function. We conclude that CR and IF dietary regimens can ameliorate age-related deficits in cognitive function by mechanisms that may or may not be related to Aβ and tau pathologies.”– Intermittent fasting and caloric restriction ameliorate age-related behavioral deficits in the triple-transgenic mouse model of Alzheimer’s disease Veerendra Kumar Madala Halagappa; Zhihong Guo; Michelle Pearson; Yasuji Matsuoka; Roy G. Cutler; Frank M. LaFerla; Mark P. Mattson,⁎ Available here: http://matsuokalab.georgetown.edu/pubs/2007%20Neurobiol%20Dis%20Caloric%20restriction.pdf
Lastly, there is evidence that IF can provide the same benefits to resting glucose and insulin sensitivity as a reduced calorie diet, even if the subject ends up eating as many calories (over a 48 hour time period) as they would had they not been restricted in any way:
“The findings of this study suggest that IF can enhance health and cellular resistance to disease even if the fasting period is followed by a period of overeating such that overall caloric intake is not decreased.”– Intermittent fasting dissociates beneficial effects of dietary restriction on glucose metabolism and neuronal resistance to injury from calorie intake R. Michael Anson, Zhihong Guo, Rafael de Cabo, Titilola Iyun, Michelle Rios, Adrienne Hagepanos, Donald K. Ingram, Mark A. Lane, Mark P. Mattson Available here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC156352/
I have never done IF, but writing this article has made me reevaluate my eating schedule. I’d love to try this, my only concern is the social aspect of it.
Have you ever fasted for health reasons? How did it go?
Do you practice IF? Why?