Why exercise alone won't get those extra kilos off

Washington: Gym bunnies, you may be wasting your time as a new study has revealed that exercise by itself isn't always enough to shed those extra kilos.

According to the City University of New York study, exercise alone will not help because our bodies adapt to higher activity levels, so that people don't necessarily burn extra calories even if they exercise more.

Researcher Herman Pontzer said that 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."

People who start exercise programs to lose weight often see a decline in weight loss (or even a reversal) after a few months. Large comparative studies have also shown that people with very active lifestyles have similar daily energy expenditure to people in more sedentary populations.

Pontzer says this really hit home for him when he was working among the Hadza, a population of traditional hunter-gatherers in northern Tanzania who are incredibly active, walking long distances each day and doing a lot of hard physical work as part of their everyday life.

The researchers say it's time to stop assuming that more physical activity always means more calories. There might be a "sweet spot" for physical activity too little and we're unhealthy, but too much and the body makes big adjustments in order to adapt.

The study is reported in the Cell Press journal Current Biology.