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Why exercise alone is not enough to lose weight

For the new study, published in August in Current Biology, some of the scientists involved in the initiative set out to see what happens to our metabolism when we move. They extracted data for 1,754 adults that included their double-labeled water results, as well as measures of their body composition and baseline energy expenditure – that is, the number of calories they burn. simply by being alive, even if they are otherwise inactive. Subtracting the basic numbers from total energy expenditure gave the researchers an approximation of people’s energy expenditure resulting from exercise and other movements, such as standing, walking, and general restlessness.

Then, using statistical models, the researchers were able to determine whether the calories burned during activity increased people’s daily energy expenditure as expected – that is, whether people burned proportionately more total daily calories. when they move more. But, the researchers found that they didn’t tend to burn more calories. In fact, most people seemed to only burn about 72% more calories on average, as you would expect given their activity level.

“People seem to make up at least a quarter for the extra calories burned by activity,” said Lewis Halsey, professor of life and health sciences at the University of Roehampton in London and one of the main authors of the new study.

Unexpectedly, the researchers also found that energy compensation levels increased in people with relatively high body fat levels. They tended to offset 50 percent or more of the calories they burned by being active.

It’s important to point out that the study did not examine people’s food consumption. He only focused on energy expenditure and how our bodies seem able to compensate for some of the calories burned during exercise by reducing biological activity elsewhere in the body. However, it remains unclear how we subconsciously orchestrate this feat and which internal systems could be affected the most, Dr Halsey said. He and his colleagues believe that the operations of the immune system, which require considerable energy, can be reduced somewhat. Or we might unknowingly move less or become more sedentary, overall, on the days we exercise. It may also be that some of the inner workings of our cells can slow down, reducing our body’s overall energy expenditure.

But the new science of exercise and calorie compensation isn’t completely daunting. Even people whose bodies compensate for 50 percent or more of the calories they burn during physical activity will burn more calories per day than if they stay still, Dr. Halsey pointed out. A more difficult problem to solve with using exercise for weight loss, he continued, is that exercise realistically burns low calories, period. To lose weight, you will also have to eat less.

“Half a cookie or half a can of cola” after half an hour of walking, and you’ll have absorbed more calories than you burned, he said, whether you compensated a lot or a little.

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