Exercise is the world’s best drug- it’s just not a weight loss drug.
A friend complained recently about not losing her winter paunch this summer despite swimming almost daily at the beach, combined with aerobic and weight workouts at the gym. When I pointed to the double scoop of ice cream she was happily devouring, she replied that she thought she had earned a reward for all her physical efforts.
My friend was operating under a fanciful illusion which is promoted by the fitness centre industry and glossy magazines: if you work out regularly, preferably with an expensive trainer or the magazine’s special exercises, you will lose weight and attain the body of your dreams.
But there is no scientific support for this notion. In fact, the evidence is quite the opposite. “You can’t outrun your fork,” says Yoni Freedhoff, an assistant professor of medicine at the University of Ottawa and founder of Canada’s Bariatric Medical Institute, which advises patients on non-surgical weight management.
“People tend to eat back their exercise,” Dr Freedhoff says. He notes there is an “unfair balance” between calorie consumption and calorie burning. It takes only a couple of minutes to gulp down a KitKat but the chocolate bar’s calories require more than an hour of heavy, sweaty exercise to burn off.
In fact, in one frequently cited study reported in the Journal of the American Medical Association, a group of 467 obese women was divided into four groups and put on an exercise regime with different levels of intensity; at the end of six months, none of the four groups had lost any weight.
One reason for this problem may be what is known scientifically as “hedonic compensation”, or rewarding yourself for doing something that you find unpleasant.
Carolina Werle, an assistant professor of marketing at the École de Management in Grenoble, France, recently conducted three fascinating experiments to see why people fail to lose weight with exercise.
For example, one group of people was told to engage in a fun walk while another group was given the exact same programme but was told that it was a specific form of exercise. At the end of the programme, both groups were taken to an all-you-can-eat buffet lunch. The group that had been told to exercise loaded up on fattening side dishes and pudding while the fun group ate less.
“The lesson is that the more fun we have while exercising, the less we will feel the need to compensate for it by eating more fattening food,” Ms Werle says. “It was just the perception of the activity that was different.”
Another myth, Dr Freedhoff says, is that more exercise will result in greater weight loss. Studies show that people who exercise for more than the recommended 150 minutes a week do not lose more weight than those who exercise less. They continue to gain weight, just at a slower pace, he says.
No one is suggesting that people abandon exercise programmes simply because they are not a good way to lose weight.
“The sad truth is there is nothing more beneficial to health than exercise,” Dr Freedhoff says. “When people don’t lose weight with this intervention, then they quit because the one thing they were told it was going to do, it doesn’t do.
“Exercise is the world’s best drug. It’s just not a weight loss drug.”