Our bodies adapt to anything above a moderate level of exercise and stop increasing daily energy expenditure, says a new study published today in Current Biology. The researchers found that exercising heavily won’t help you lose weight as our bodies make up for higher physical activity by conserving energy in other ways. Herman Pontzer, of City University New York, was inspired to create the study when he was working in Tanzania among the Hadza, a group of traditional hunter-gatherers. He discovered that, despite their very active lifestyles, they burned a similar amount of energy per day as people living more sedentary, modernized lives in the U.S. and Europe.
We spoke to Pontzer to discuss the study further and to find out what the ’sweet spot' for physical activity could be.
ResearchGate: What were the key findings from your research into the effect exercise has on energy expenditure?
Herman Pontzer: For people doing moderate levels of physical activity or higher, daily energy expenditure (calories burned per day) did not increase with activity level.
RG: Can you explain your study’s design?
Pontzer: 332 adults from five global populations (Ghana, Seychelles, South Africa, Jamaica, and the US) participated. Daily energy expenditure was measured using the doubly labeled water method, a technique that tracks the body’s production of carbon dioxide, which is directly linked to energy expenditure. Physical activity was measured using an accelerometer. These measurements were done for a period of seven days, providing a solid measurement of average daily energy expenditure and daily activity. We used those measurements to examine the relationship between energy expenditure and physical activity.
