Does exercise make you FAT? Experts say we're deluded about ...

Study found that while more people are active in the U.S., it has not reduced the number of people who are considered overweight Estimated that around a third of people are in UK and U.S. are overweight Experts said there is a 'war between exercise and nutrition in our heads' Added that exercise is probably better for weight maintenance than loss It takes an hour and a quarter of intensive cycling to burn a medium shop-bought pizza

By Rachel Reilly

PUBLISHED: 09:04 EST, 22 July 2013 | UPDATED: 09:11 EST, 22 July 2013

If you're working up a sweat in the gym but still not managing to lose weight, then overgenerous post-workout treats could be to blame.

Although exercise has its indisputable health benefits, experts have said that many well-intentioned gym goers overestimate how many calories they have burned, and in turn indulge in too many sugary and fat-laden snacks.

For example, it takes over an hour of intensive cycling to burn a medium shop-bought pizza.

'There's a war between exercise and nutrition in our heads,' said Jonathan Ross, spokesperson for the American Council on Exercise.

'People tend to overestimate the amount of physical activity they get. They work out a little bit and treat themselves a lot.'

A report by the University of Washington's Institute for Health Metrics and Evaluation found that although Americans say they are more active, it has not made much of a dent in the obesity epidemic that affects more than one-third of U.S. and UK adults.

HOW MUCH EXERCISE DO YOU NEED TO DO TO BURN OFF THAT TREAT?

Mr Ross, a personal trainer based outside Washington D.C., said exercise can play a role in weight reduction, but without broader lifestyle and nutritional changes, that role is limited.

'We put exercise in a box and once that exercise box is filled in we don't do much the rest of the day,' he explained, adding that a calorie-dense treat does not help.

'Some (weight-loss) programs stress nutrition, some stress exercise,' he told Reuters Health. 'But the two together are greater than the parts.'

The National Weight Control Registry, which gathers information from people who have successfully lost at least 30 pounds (13 kg) and kept it off for a least one year, reported that 90 per cent of its members exercise, on average, about one hour per day.

U.S. health officials recommend that healthy adults get at least 150 minutes of moderate-intensity physical activity a week, or around 20 minutes a day.

Dr Joseph Donnelly, an exercise physiologist with the American College of Sports Medicine said the U.S. government guidelines are for cardiovascular fitness, not weight loss.

'It was never intended for weight management, said Dr Donnelly, a researcher who focuses on obesity at the University of Kansas. 'People have misused it.'

He added that studies suggest 250 to 300 minutes of exercise per week may be the minimum to lose weight: 'At 150 minutes, the best you can hope for is weight maintenance.'

Dr Michele Olson, professor of exercise physiology at Auburn University Montgomery, in Alabama, said it is difficult to shed pounds through exercise alone.

'One pound of fat has 3,500 calories,' she explained. 'If you ran a 26-mile marathon, where you burn about 100 calories per mile, you would burn 2,600 calories, falling 900 calories short of burning one pound of fat.'

She added that people must be physically active regardless of their size or whether they are losing weight.

'Moderately intense exercise done in as few as 10-minute increments two to three times a day markedly reduces our risk of all causes of mortality, heart disease most effectively but all other causes, including cancers, deaths due to hypertension and strokes, etc,' she said.