Saturday, May 15, 2010

Intermittent fasting as a form of liberation

I have been doing a lot of reading over the years on isolated hunter-gatherer populations; see three references at the end of this post, all superb sources (Chagnon’s book on the Yanomamo, in particular, is an absolute page turner). I also take every opportunity I have to talk with anthropologists and other researchers who have had field experience with hunter-gatherer groups. Even yesterday I was talking to a researcher who spent many years living among isolated native Brazilian groups in the Amazon.

Maybe I have been reading too much into those descriptions, but it seems to me that one distinctive feature of many adults in hunter-gatherer populations, when compared with adults in urban populations, is that the hunter-gatherers are a lot less obsessed with food.

Interestingly, this seems to be a common characteristic of physically active children. They want to play, and eating is often an afterthought, an interruption of play. Sedentary children, who play indoors, can and often want to eat while they play.

Perhaps adult hunter-gatherers are more like physically active children than adults in modern urban societies. Maybe this is one of the reasons why adult hunter-gatherers have much less body fat. Take a look at the photo below (click to enlarge), from Wikipedia. It was reportedly taken in 1939, and shows three Australian aboriginals.

Hunter-gatherers do not have supermarkets, and active children need food to grow healthy. Adult urbanites have easy access to an abundance of food in supermarkets, and they do not need food to grow, at least not vertically.

Still, adult hunter-gatherers and children who are physically active are generally much less concerned about food than adults in modern urban societies.

It seems illogical, a bit like a mental disorder of some sort that has been plaguing adults in modern urban societies. A mental disorder that contributes to making them obese.

Modern urbanites are constantly worried about food. And also about material possessions, bills, taxes etc. They want to accumulate as much wealth as their personal circumstances allow them, so that they can retire and pay for medical expenses. They must worry about paying for their children’s education. Food is one of their many worries; for many it is the biggest of them all. Too much food makes you fat, too little makes you lose muscle (not really true, but a widespread belief).

Generally speaking, intermittent fasting is very good for human health. Humans seem to have evolved to be episodic eaters, being in the fasted state most of the time. This is perhaps why intermittent fasting significantly reduces levels of inflammation markers, promotes the recycling of “messed up” proteins (e.g., glycated proteins), and increases leptin and insulin sensitivity. It is something natural. I am talking about fasting 24 h at a time (or a bit more, but not much more than that), with plenty of water but no calories. Even skipping a meal now and then, when you are busy with other things, is a form of intermittent fasting.

Now, the idea that our hominid ancestors were starving most of the time does not make a lot of sense, at least not when we think about Homo sapiens, as opposed to earlier ancestors (e.g., the Australopithecines). Even archaic Homo sapiens, dating back to 500 thousand years ago, were probably too smart to be constantly starving. Moreover, the African savannas, where Homo sapiens emerged, were not the type of environment where a smart and social species would be hungry for too long.

Yet, intermittent fasting probably happened frequently among our Homo sapiens ancestors, for the same reason that it happens among hunter-gatherers and active children today. My guess is that, by and large, our ancestors were simply not too worried about food. They ate it because they were hungry, probably at regular times – as most hunter-gatherers do. They skipped meals from time to time.

They certainly did not eat to increase their metabolism, raise their thyroid hormone levels, or have a balanced macronutrient intake.

There were no doubt special occasions when people gathered for a meal as a social activity, but probably the focus was on the social activity, and secondarily on the food.

Of course, they did not have doughnuts around, or foods engineered to make people addicted to them. That probably made things a little easier.

Successful body fat loss through intermittent fasting requires a change in mindset.


Boaz, N.T., & Almquist, A.J. (2001). Biological anthropology: A synthetic approach to human evolution. Upper Saddle River, NJ: Prentice Hall.

Chagnon, N.A. (1977). Yanomamo: The fierce people. New York, NY: Holt, Rinehart and Winston.

Price, W.A. (2008). Nutrition and physical degeneration. La Mesa, CA: Price-Pottenger Nutrition Foundation.