To lose weight , exercise alone is not enough because people sit too much today.That's what the latest research has shown.Marc Hamilton led a team of scientists to do a research at the University of Missouri. Scientists have been wondering why so many people take exercise every day but they are still overweight.This research was designed to find the reason.In the experiments , Hamilton used a few lab mice and pigs , as well as twelve human volunteers (志愿者), including himself.He wanted to learn more about the effects (作用) of sitting.When the lab anim als were sitting down , lipase—a material in the body that does the job of reducing fat—went down to 10 percent of normal after several hours.The research team got the same result from the experiments with humans. “It was hard to believe at first , ” said Hamilton , “but it's true.” Those who exercise daily spend much more time sitting during the rest of the days , and the longer they are sitting , the more fat they get.Hamilton advises , “Keep exercising every day , but remember to stand up and take a walk from time to time during the day.”