Why we dont lose weight from exercise alone

We won't lose weight with exercise alone

Did you know that we don't necessarily burn extra calories when we exercise more? This is according to new research reported in the Cell Press journal Current Biology.

Does this mean that exercise is pointless?

While the researchers say it’s time to rethink the effect of physical activity on daily energy expenditure, they urge us to remember the importance of both diet and exercise in supporting weight-loss goals.

"Exercise is really important for your health," says Herman Pontzer of City University of New York. "That's the first thing I mention to anyone asking about the implications of this work for exercise. 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 doing more exercise doesn’t burn more calories

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

People with moderate activity levels had a higher daily energy expenditure - about 200 calories higher - than sedentary people but, people with above moderate activity levels saw no extra energy expenditure.

Pontzer says this really hit home for him when he was working among the Hadza, a population of traditional hunter-gatherers in northern Tanzania.

"The Hadza are incredibly active, walking long distances each day and doing a lot of hard physical work as part of their everyday life," Pontzer says. "Despite these high activity levels, we found that they had similar daily energy expenditures to people living more sedentary, modernized lifestyles in the United States and Europe. That was a real surprise, and it got me thinking about the link between activity and energy expenditure."

Over 300 men and women studied

To explore this question further in the new study, Pontzer and his colleagues measured the daily energy expenditure and activity levels of more than 300 men and women over the course of a week.

Finding the exercise sweet spot

The researchers found that people with moderate activity levels had a somewhat higher daily energy expenditures - about 200 calories higher - than sedentary people. However, people who fell above moderate activity levels saw no effect of their extra work in terms of energy expenditure.

"The most physically active people expended the same [number] of calories each day as people who were only moderately active," Pontzer says.

The researchers say it's time to stop assuming that more physical activity always means burning 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.

1. Prev:5 Weight-loss lifestyle tips that make all the difference
2. Next:Drink yourself skinny - how to cut calories by 20%