When accounting for differences in body size, increasing physical activity does not lead to a proportional increase in the total amount of energy the body uses per day.

We analyzed the available evidence on whether total daily energy expenditure increases proportionally with physical activity after adjusting for body size, and what we’ve found so far is mixed. Fifty-one studies suggest that when you account for differences in body size, increasing physical activity does not lead to a proportional rise in total daily energy use [1]. At the same time, 36 other studies or assertions contradict this, indicating that energy expenditure may still rise in line with activity levels even after adjusting for size [1]. This means the relationship between movement and total calorie burn isn’t as straightforward as it might seem. Even when people move more, their bodies may adapt in ways that limit how much extra energy they burn overall — perhaps by reducing energy spent on other processes like digestion or movement at rest. But not all studies agree on how strong or consistent this effect is. Our current analysis shows that while many studies point to a leveling off of energy expenditure with higher activity levels, others find a clearer connection between movement and total burn. The evidence we’ve reviewed leans toward the idea that the body may compensate in subtle ways, but we can’t say this happens the same way for everyone. What this means in everyday terms: if you’re trying to burn more calories by moving more, your body might adjust behind the scenes — so the extra calories you expect to burn might not always show up on the scale. Increasing activity is still helpful for health, but don’t assume more movement always equals more total calories burned.