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We are what we eat, but the human body is a very complicated machine and unlike a car that consumes more fuel the further it goes, the human body’s fuel economy works in a very different manner. New research sheds light on this difference.

Exercising appears to have a large impact on fat burning for beginners, but as the training dose increases, the effect of the increase, decrease.

Herman Pontzer is a professor of anthropology at the City University of New York, he believes that this apparent decreasing net effect of increasing exercise may be due to different factors. Perhaps very eager exercisers move less after training to unconsciously compensate. Or perhaps hard muscle work causes the body to cut down on other energy consuming processes.

Pontzer leads a research team that has mapped the energy metabolism and physical activity among over 300 women and men. The research clearly shows that above a certain level of activity, energy output flattens off, but this level varies from person to person.

The benefits of physical activity on health is still evident, however, but for those who want to lose weight and are already exercising, it is more efficient to focus more on diet than to exercise more.

Constrained Total Energy Expenditure and Metabolic Adaptation to Physical Activity in Adult Humans