Can working out help us drop pounds after all?
A provocative new study involving overweight men and women suggests that it probably can, undercutting a widespread notion that exercise, by itself, is worthless for weight loss. But the findings also indicate that, to benefit, we may need to exercise quite a bit.
In theory, exercise should contribute substantially to weight loss. It burns calories. If we do not replace them, our bodies should achieve negative energy balance, use stored fat for fuel and shed pounds.
But life and our metabolisms are not predictable or fair, as multiple exercise studies involving people and animals show. In these experiments, participants lose less weight than would be expected, given the energy they expend during exercise.
The studies generally have concluded that the exercisers had compensated for the energy they expended during exercise, either by eating more or moving less throughout the day. These compensations were often unwitting but effective.
Some researchers had begun to wonder, though, if the amount of exercise might matter. Many of the past human experiments had involved about 30 minutes a day or so of moderate exercise, which is the amount generally recommended by current guidelines to improve health.
But what if people exercised more, some researchers asked. Would they still compensate for all the calories that they burned?