Exercise can be a powerful balm for many of the things that ail us, including depression, bone loss, fatigue, heart disease, diabetes and arthritis. But the reason many of us pound the pavement is because we want to lose weight, and that, experts say, is a goal for which exercise alone may not be especially helpful. 

Monitoring your diet – specifically portion control – is more effective than exercise for weight loss. The reason boils down to simple math. It is far easier to eat 100 calories – the amount in a piece of bread – than it is to burn them off, which, for most of us, would require walking one mile. And while exercise helps us burn more calories, it also increases appetite, making it excruciatingly easy to undo all that hard work.

In the position paper “Physical Activity and Public Health: Updated Recommendations for Adults from the American College of Sports Medicine and the American Heart Association” which was published in 2007, a blue ribbon panel of experts reviewed all available scientific evidence on the connections between exercise and health and conceded that while exercise is critical for many aspects of health, it doesn’t seem to help with weight loss.

“Despite the intuitive appeal of the idea that physical activity helps in losing weight,” the panel wrote, “it appears to produce only modest increments of weight loss beyond those achieved by dietary measures and its effects no doubt vary among people.”

Amy Luke, PhD, a nutritional epidemiologist at Loyola University, Stritch School of Medicine, in Chicago, has seen this phenomenon for herself. 

Luke compared two populations of black women: One group was from rural Nigeria, while the other was from downtown Chicago. All body size measurements were lower in the Nigerian women, and Luke and her team set out to understand why.