Weight Loss: Diet With a Side of Exercise

Exercise alone probably won't help weight loss

(RxWiki News) Exercise is important when you're trying to lose weight, but it may not be the only factor.

In a new study, researchers from City University of New York (CUNY) found that the body adapts well to exercise. It adapts so well, in fact, that increased exercise isn't much help when it comes to weight loss. In other words, the body's reaction to exercise levels off after a period of increased metabolism.

Lead study author Herman Pontzer, PhD, a professor of anthropology at CUNY, said in a press release, "There is tons of evidence that exercise is important for keeping our bodies and minds healthy, and this work does nothing to change that message. What our work adds is that we also need to focus on diet, particularly when it comes to managing our weight and preventing or reversing unhealthy weight gain."

When someone who was previously sedentary begins to exercise regularly, the body burns more calories from food or stored fat than it did before. As the body adapts to the increased level of exercise, however, fewer calories are needed for the same amount of effort. This leads to a decline in weight loss.

Dr. Pontzner and team previously studied a group of traditional hunter-gatherers in northern Tanzania called the Hadza. The Hadza walk long distances each day and routinely engage in hard physical labor.

The Hadza were found to burn relatively few calories per day, however. Researchers speculated that this was because their bodies were adapted to high levels of exercise.

To confirm this theory, Dr. Pontzner and team looked at 300 US men and women over the course of one week. Compared to sedentary people, those who were moderately active burned about 200 more calories per day.

People who were less physically active burned more calories as they increased their activity level. People who were normally more active, however, didn't burn any more calories when they became more active.

In spite of these findings, Dr. Pontzner and team said that people looking to lose weight should still exercise regularly.

The take-away message for the average person, researchers noted, is that more physical activity doesn't necessarily mean you'll burn more calories — especially over the long term. To lose weight effectively, dietary changes have to be included as well.

This study was published Jan. 28 in the journal Current Biology.

The National Institutes of Health funded this research. No conflicts of interest were disclosed.

Review Date: 
January 21, 2016