24/02/2026
This week, I want to focus on one scientist whose work shapes understanding of how the human body uses energy—and whose conclusions are very important for anyone deciding how much to eat, how much to exercise, how much energy to consume, and how much to burn. It seems that what we have been guided by until now is, to put it mildly, inaccurate and impractical.
I am talking about Herman Pontzer – for those who want to find out more. It is important to mention that his field is anthropology, but neither his research methods nor his logic raises any doubts in my mind. However, I strongly urge you to draw your own conclusions, and if you are interested, let's discuss it. The data for the research were collected by observing (and measuring) the Hadza nomadic tribe in Tanzania. Although each member of the tribe is much more physically active during the day, they consume almost as much energy as the average Westerner with a sedentary lifestyle.
More physically active people consume the same amount of energy as sedentary.
How does this happen? After all, doesn't more movement require more energy? The more you move, the more you burn, right? No, that's not how it works. Here's how the author of the study explains this phenomenon. Pontzer claims that regardless of whether you move more or less, energy is redistributed elsewhere. If we move more, then yes, of course, more energy is allocated to movement, and less is left for "other things." If we move less, then less is allocated to movement and more to "other things." Other things include immune response, reproductive substances, and stress response.
When the nature of physical activity changes, the energy balance also changes; in about 6 weeks, the body responds to the change in energy needs and then returns to its original level. How does this happen? The body can produce approximately the same amount of energy per unit of time. When energy needs increase, it is conserved. In immune responses, energy allocated to maintaining the inflammatory response is reduced, and levels of cytokines and C-reactive protein decrease. It is the main reason why exercise is healthy; this reaction suppresses chronic inflammation and reduces the risk of cardiovascular disease, diabetes, and cancer.
In some cases, the immune response weakens to the point that the person becomes ill. In the case of reproductive signals, estrogen and progesterone levels decrease in women, and testosterone levels decrease in men. Although this is a healthy effect in the case of moderate physical activity, in extreme cases, athletes experience effects such as women losing their periods. In the case of a stress response, the level of cortisol produced decreases; this is also logical—a stress response requires a lot of energy, and if it is used elsewhere (for physical activity), it is no longer allocated to the stress response. In this way, physical activity has a calming effect, although in reality, it is the chemicals involved in the stress response that are no longer being produced. In addition, the renewal of some cells and non-critical tissues slows down. The body constantly adapts to its energy needs – the more we exercise, the better the body adapts.
Let's return to limits. A person cannot consume more than 2.5 times their basal metabolic rate if this need lasts longer than a few weeks. Temporary changes are accommodated, but in the long run, the body adapts. Here, it is more important than ever to consider why something may change temporarily during a diet, but then everything returns to normal, and often becomes even worse. In addition, the digestive tract cannot process and absorb more nutrients than its limit. We already burn more calories than our primate relatives, simply because we have large and hungry brains. Therefore, we have a much more efficient mechanism for storing body fat. However, when it comes to energy consumption and use, exercise helps us stay healthy, while conscious choices about food quality and quantity help us stay slim. The healthiest choice is moderate-intensity physical activity—neither very low nor very high levels of exercise are healthy. According to Herman Pontzer, excess food inevitably leads to excess weight. In our evolution, we have developed a tendency to absorb everything we eat as reserves because we have always (except in modern times) lived in conditions of food scarcity. We do not have a mechanism to get rid of excess food, and exercise is not the way we would like it to be. We cannot sweat or walk off yesterday's lavish feast. Eating more food also requires more energy to digest it, but this accounts for about 10 per cent of the energy we get from food. Therefore, there will never be a situation in which digesting the food we eat requires more energy than we get from it. People who eat more than their bodies need also produce more heat (read about NEAT, Non-Exercise Activity Thermogenesis) because they move more involuntarily or unconsciously. In addition, it is worth knowing that when any calculator says "you burned 300 calories," this is not the case; at best, it is about 90 kilocalories, and the rest was compensated for in other ways. The idea that energy is burned in the same way as in a wood-burning stove is very convenient, but very inaccurate.
Therefore, it is much more important to pay attention to what we eat, why we crave certain foods (ultra-processed foods trick our receptors and brains into thinking they are particularly valuable), the speed at which we eat (we do not have the mechanism to process particularly large amounts of calories very quickly – and with high-calorie foods, we get just that, a particularly large amount, and regulate the calorie content of our food according to what the scales show us. Most of the energy we get from food is consumed by our internal organs (brain, liver, heart, kidneys) – so trying to burn it through muscle doesn't seem logical. Yes, more muscle means more energy consumption, but the increase won't be significant. A more promising approach is not to eat too much, rather than looking for ways to burn off the excess.
Please read the author's research or find his comments on social media. To start with, I recommend the following:
Pontzer, H., Raichlen, D. A., Wood, B. M., Mabulla, A. Z. P., Racette, S. B., & Marlowe, F. W. (2012). Hunter-gatherer energetics and human obesity. PLOS ONE, 7(7), e40503. https://doi.org/10.1371/journal.pone.0040503
Pontzer, H., Durazo-Arvizu, R., Dugas, L. R., Plange-Rhule, J., Bovet, P., Forrester, T. E., Lambert, E. V., Cooper, R. S., Schoeller, D. A., & Luke, A. H. (2016). Constrained total energy expenditure and metabolic adaptation to physical activity in adult humans. Current Biology, 26(3), 410–417. https://doi.org/10.1016/j.cub.2015.12.046
Pontzer, H., Brown, M. H., Raichlen, D. A., Dunsworth, H., Hare, B., Walker, K., Luke, A., Dugas, L. R., Durazo-Arvizu, R., Schoeller, D., Plange-Rhule, J., Bovet, P., Forrester, T. E., & Lambert, E. V. (2016). Metabolic acceleration and the evolution of human brain size and life history. Nature, 533(7603), 390–392. https://doi.org/10.1038/nature17654
Thurber, C., Dugas, L. R., Ocobock, C., Carlson, B., Speakman, J. R., & Pontzer, H. (2019). Extreme events reveal an alimentary limit on sustained maximal human energy expenditure. Science Advances, 5(6), eaaw0341. https://doi.org/10.1126/sciadv.aaw0341
Pontzer, H., Yamada, Y., Sagayama, H., Ainslie, P. N., Andersen, L. F., Anderson, L. J., Arab, L., Baddou, I., Bedu-Addo, K., Blaak, E. E., Blanc, S., Bonomi, A. G., Bouten, C. V. C., Bovet, P., Buchowski, M. S., ... & Speakman, J. R. (2021). Daily energy expenditure through the human life course. Science, 373(6556), 808–812. https://doi.org/10.1126/science.abe5017
You can give it more thought while reading this book: Herman Pontzer "Burn"
