Maybe you've noticed lately that even when you do a lot of exercise, you aren't necessarily losing any weight. Not, of course, unless you also change your eating habits.
A study published online in September in The British Journal of Sports Medicine found that 58 obese people who finished 12 weeks of aerobic training exercises, while staying on their current diet, shed a very modest amount of weight. The average loss for the group as a whole was seven pounds, but the researchers say many participants lost more like half of that.
This study joins groups of other research that shows that exercise alone won't allow you to shed weight. It must be combined with a food diet plan. The New York Times reports on a A new study by scientists at the University of Colorado School of Medicine in Denver focused on several groups of people. Some were thin endurance athletes, others were lean, but not very active, and some were just inactive or obese.
Over the course of the experiment, each subject spent several 24-hour sessions in a special laboratory room. The room housed a calorimeter, which was able to measure the number of calories a person burns. The researchers could then calculate whether the calories consumed were either fat or carbohydrates. The time spent in the lab room was followed by another 24-hour period that included a one-hour session on a stationary bicycle. The cycling was set at a relatively easy intensity pace. All of the study participants ate three meals a day.
The result of the study was that none of the groups, including the lean athletes experienced what is known as an "after-burn". Researchers found to their surprise that most of the subjects burned slightly less fat over the 24-hour study period when they exercised than when they did not.
Scientists say this doesn't mean that you shouldn't exercise. But they caution that working out at an easy intensity will burn a higher percentage of fat calories than if you work out at a higher intensity. They also point out that exercise has benefits of its own, beyond weight reduction. They say the obese people who were in the study increased their aerobic capacity, decreased their blood pressure and resting heart rates and achieved a more positive mood for themselves.
But there is one final hopeful note about exercise. Researchers say it helps to keep off body fat that has been erased through diligent calorie reduction. In fact, laboratory rates that were overfed, then slimmed down through low-calorie diets, were able to defend that lower weight more effectively if they ran on a treadmill than if they didn't.