Hunter-gatherers most likely to be leaner than us due to differences in diet, not activity

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Obesity is essentially unknown in populations that live a traditional ‘hunter-gatherer’ way of life. As is well recognised, it’s different in Westernised populations. Why? Well, one theory, at least, is that hunter-gatherers are much more active, and are burning off more calories than their Western counterparts, which affords them the ability to maintain health weights. It’s a plausible theory, but new research suggests it may well be utterly wrong too.

In a study published in the journal PLoS One here researchers measured the energy expenditure of the Hadza – a hunter-gatherer population living in northern Tanzania in East Africa [1]. The method of measuring energy expenditure in this study (doubly labelled water) is recognised as accurate. The total energy expenditure in a group of 30 Hadza was compared to that data from ‘Westerners’. The result? Once body weight was taken into account (bigger people tend to burn more calories), energy expenditure was essentially the same.

In other words, this evidence points away from differences in activity and energy expenditure as being a major explanation for why hunter-gatherer populations tend to be much lighter than those living a more Westernised existence.

If the evidence points away from energy expenditure, then it also probably more points towards energy intake as a or perhaps the major differentiating factor.

But I feel we’ve been here before, in that the evidence as a whole shows that if weight and fat loss are the goal, efforts in a dietary direction pays much more handsome dividends than exercise. This is not to decry activity and exercise: there are many benefits to be had from these endeavours, it’s just that significant weight loss is rarely one of them.

So, what it is about the diet of the Hadza that appears to make them resistant to obesity? Is it that they don’t eat that much, because of reduced food availability? Is it something to do with the quality of the diet, more than the quantity? Could a primal diet have hormonal and metabolic effects that help protect against obesity? Or is it a bit of both? Is it possible that, for instance, the type of food eaten in a primitive diet somehow protects against overeating by sating the appetite more fully and guarding against overeating?

There is some evidence which shows that opting for a primal diet naturally shaves an average of a few hundred calories off individuals’ intakes compared to when they are eating a more Western ‘Mediterranean’ diet [2].

How does this happen? I don’t know for certain, but there are at least a few ideas floating out there. Here’s a few:

  • Many sugary and starchy Western foods are destabilising for blood sugar levels, and may trigger false hunger and food cravings due to episodes of rapidly falling and/or low blood sugar levels. More primitive diets are more stabilising to blood sugar, and may be less prone to inducing false hunger as a result.
  • Primitive diets may offer relatively more protein than Western diets, and protein has been found to offer more appetite-sating potential than fat or carbohydrate.
  • Some hunger and food seeking behaviour may be the result of relative deficiencies in key brain chemicals including serotonin and endorphins. Brain chemicals such as these are made from amino acids, and a protein-rich diet may help counter these imbalance by helping to optimise amino acid and brain chemical levels. These and other issues are explored comprehensively in the recently-updated The Diet Cure by Julia Ross.
  • Primitive and primal diets are generally devoid of ‘rewarding’ foods that can drive overeating. The theory that food reward is a major driver of obesity has been popularised by Dr Stephan Guyenet over at A primitive diet will also be devoid of foods that have been deliberately crafted to be rewarding and moreish.

Untangling what it is about diets made up of natural unprocessed foods make them, for most people, inherently more satisfying may take some time, if it happens at all. More important, I think, is the fact that I’ve seen many individuals lose considerable quantities of weight and maintain that loss as a result of adopting a diet which is inherently satisfying and does not require having to put up with undue hunger.

I’ve seen, time and again, how eating the right sort of diet helps control the appetite and makes it easy to eat the right sort of diet. My overwhelming experience is that when someone changes what they eat in an effort to lose weight, the less hungry they are the more weight they lose and the easier they tend to find it to maintain that loss. My experience is also that eating a more ‘primal’ diet is an extremely powerful tool here.


1. Pontzer H, et al. Hunter-Gatherer Energetics and Human Obesity. PLoS ONE 7(7): e40503. doi:10.1371/journal.pone.0040503

2. Jonsson T, et al. A Paleolithic diet is more satiating per calorie than a Mediterranean-like diet in individuals with ischemic heart disease. Nutr Metab (Lond) 2010;30(7):85

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