Over time, the benefits of exercise for weight loss diminish as the body compensates, and this is more pronounced in obese or overweight people.
Weight loss is often a very complex endeavor. It requires effort in terms of diet, exercise, and sleep. Worse still, a new study suggests that exercise reduces the number of calories burned at rest, making it very difficult to rely solely on physical activity to lose weight. The study, published in the journal Current Biology on 27 August, adds that this compensation by the body is even greater in obese and overweight people.
The body compensates for energy expenditure
The body seems designed to make weight loss as difficult as possible. At first glance, this seems simple: all that is needed is an increase in physical activity to increase energy expenditure. The problem is that the body doesn’t work like that, especially in the long term. This is because the body automatically reduces its basal metabolic rate when it increases physical activity, which is a kind of compensation. And that makes it harder to lose weight.
To illustrate this, Gilmore Health used an example that shows this clearly. If you burn 200 calories due to physical activity, this should theoretically increase your energy expenditure by 200 calories. In reality, if it works for the first few days, over time this calculation stops applying. The body compensates for this increased energy expenditure by reducing expenditure elsewhere, such as in metabolism or thermogenesis. In the study, researchers estimate this energy compensation at 28%. In the example above, this means that for a 200 calorie expenditure, the actual additional energy expenditure is only 144 calories. “It’s like the government trying to balance the budget. If you spend more money on education, there is less money for road maintenance,” Lewis Halsey, a researcher at the University of Roehampton in the UK and co-author of the study, told the Guardian.
A misunderstood mechanism
Worse still, the researchers found that the phenomenon is even greater in people who are obese or overweight. Energy compensation can be as high as 49.2%. It’s possible that people with higher levels of fat become more ‘compensatory’ as they get fatter,” believes Lewis Halsey. Consequently, there is a negative feedback loop where exercise becomes less effective in losing weight.”
The researchers were unable to provide a clear explanation for this mechanism. They confirmed that this is a topic for future research. “We also need to assess whether a decrease in basal metabolic rate leads to side effects, such as a weakened immune system or slower recovery from injury, in order to calculate when exercise becomes less effective,” they conclude.
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