Exercise paradox

The exercise paradox, as coined by the biological anthropologist Herman Pontzer, refers to scientific evidence which contradicts the long-held belief that the more physical exercise, the more calories burnt.

Exercise & Lifestyle vs. Metabolic Expenditure

Recent evidence (which is now available due to advanced metabolic measurement techniques such as the doubly labeled water method) shows that total daily caloric expenditure is constrained, with a minimum and maximum amount of calories burnt per day. In addition, there is no significant difference in calories burnt when taking into account either sedentary or active lifestyles (e.g., zoo animals and animals in the wild; adult humans in a sedentary lifestyle or a member of a hunter-gather community). This is opposed to conventional wisdom that "exercise is key to losing weight".

Scientific evident also shows that, while total calories burnt do not wholly cause significant and long-term weight loss, physical activity is necessary for preventing and maintaining human health, beyond body weight (although the exact mechanisms are not yet well understood).

With regard to how exercise can be ineffective for long-term weight loss, the daily constrained metabolic model explains how one's daily caloric intake (from food) can be higher than one's caloric expenditure (from voluntary and involuntary bodily functions -- such as immune system, exercise, etc -- which are, as a whole, constrained daily over short time periods). Such an offset can lead to weight gain, since caloric intake may easily be more than calories burnt, depending on an individual's lifestyle.

Scientific Evidence

Hadza tribe case study

The exercise paradox emerged from studies comparing calorie expenditure between different populations. Fieldwork on the Hadza people, a hunter-gatherer tribe in Tanzania, revealed that despite their high levels of physical activity, the tribe burned a similar number of calories per day as sedentary individuals in industrialized societies. This finding, led by Duke University professor Herman Pontzer, contradicted the expectation that more active lifestyles would result in higher energy expenditures.

In 2012, Pontzer and his team of researchers analyzed energy expenditure in 30 Hadza adults using the doubly labeled water method. Participants consumed water enriched with two distinct isotopes of hydrogen and oxygen. The team later assessed the concentration of these isotopes in urine samples, which correlates with the body's daily carbon dioxide production and, consequently, daily energy expenditure.

Results indicated that Hadza women burned an average of 1,877 calories per day, which was nearly the same as the 1,864 calories burned daily by women in industrialized nations. Hadza men expended about 2,649 calories per day, which was within the standard error distribution for average calories burned by men per day in industrialized nations.

The studies suggest that controlling caloric intake may be more necessary for managing weight than exercise alone.

Studies on other population groups

A 2011 meta-analysis of 98 studies found that individuals in low to middle-HDI countries (specifically, Bolivia, Cameroon, China, Gambia, Guatemala, India, Jamaica, Nigeria, Russia, South Africa, and Eswatini) showed no significant differences in energy expenditure compared to individuals in middle to high-HDI countries (specifically, the countries of Europe, United States, Canada, Mexico, Cuba, Chile, Brazil, Japan, Australia, and New Zealand), despite large differences in each country's obesity rate.

Alternative Terminology

Pontzer's term has also been referred to as the workout paradox.

See also

• Daniel Lieberman, paleoanthropologist at Harvard University and barefoot running proponent
• Herman Pontzer, biological anthropologist at Duke Univeristy
• Benefits of physical activity
• Plateau effect
• Set point theory