Fidgets against fat

 作者:闻人揞     |      日期:2019-03-08 07:13:02
By Hazel Muir IF YOU pigged out over Christmas but still stayed trim, it might be because you fidget a lot. A new report suggests that when people overeat, they can burn up extra calories in spontaneous movements such as fidgeting, helping to keep them slim. Some people put on weight easily after eating too much, while others naturally resist piling on the pounds. But why some people stay slim has been unclear. Perhaps their metabolic rates increase and burn up more calories, or maybe they expend more energy digesting food. Alternatively, they could burn up more energy by moving spontaneously— fidgeting, twitching their muscles and staying on their feet, for instance. To test these ideas, James Levine and his colleagues at the Mayo Clinic in Rochester, Minnesota, calculated the normal daily energy expenditures and metabolic rates of 12 men and four women. Having figured out how much food the volunteers needed to maintain their weights, the team overfed them by an extra 1000 kilocalories a day for 8 weeks, ensuring that the volunteers maintained constant low levels of deliberate exercise. All the volunteers gained weight, but the amount varied more than tenfold, ranging from 0.36 to 4.23 kilograms. Metabolic rates rose a little, as did the amount of energy they expended while digesting food. But only increases in spontaneous physical activity explained why some volunteers kept the fat off, with the best fat-fighter burning up more than two thirds of the extra calories in this way (Science, vol 283, p 212). Fidget factors rose least for the four women in the study, something that the researchers don’t understand. They hope to carry out larger trials to see if they can confirm the gender difference. Levine says it’s also not clear why spontaneous movements should increase when you eat too much. And no one can say whether the findings could help in the battle against obesity. “That’s the million-dollar question,” says Levine. He is keen to see what happens when a group of people is asked to consciously increase their spontaneous movements: “Is that possible? I really don’t know.” Eric Ravussin, director of obesity research at Eli Lilly in Indianapolis, Indiana, describes the work as “a very good-quality study”. “This is one more piece of the puzzle of the regulation of body weight,” he says. However, he stresses that the effect may have little to do with the causes of obesity, and thinks it is unlikely to lead to new methods of weight control. “People are born as high or low fidgeters,