Some Do And Some Don't Gain
At this time of year many people struggle to lose the extra pounds they put on by overeating during the holidays. But some people who eat too much don't end up gaining weight. Researchers at the Mayo Clinic set out to find where those extra calories end up. They report in their recent issue that there are many ways to gain weight. Some people work off that weight with physical activity they don't even notice.
There are of course two ways to control your weight--adjust how much you eat and how much you exercise. Michael Jensen and his colleagues at the Mayo Clinic in Rochester, Minnesota, wanted to find out exactly what would happen to people who ate more but who didn't compensate by changing their exercise regimes. He told that we overfed 16 volunteers by an extra 1,000 calories per day for eight weeks and then we accurately measured the fate of all of those extra calories, now much was stored in the body and how much was burned off. And what we found was there's a tremendous variability in the amount of fat that people gained.
Some people gained just a little weight, others gained a lot. So where did those extra calories go among the people who didn't gain much weight? Jensen measured their resting metabolism, and how much energy they burned off in the process of digesting the food. But changes there didn't explain the differences in weight gain. And the volunteers didn't exercise more. So, Jensen says that leaves just one explanation, which he calls non-exercise activity.
We can only surmise that it must have been through some of the activities of daily living. Perhaps things like more moving around at work, perhaps a bit more walking, maybe fidgeting, maybe changes in posture that might increase some extra calories being burned. And the odd thing is that people didn't even notice that was happening. In fact most of our volunteers when we spoke with them actually felt a bit more sluggish after eating all this extra food day after day. But the effect of this non-exercise activity was substantial. On average, the volunteers would have had to walk several miles a day to burn off that many calories. Now scientists have known for a long time that this kind of activity can help control weight, but researchers are now able to measure its effect carefully and they're starting to figure out why it's so much more important in certain people. Eric Ravison(ph) studied this kind of activity by putting volunteers into test chambers and measuring their activities with motion detectors like the ones used in burglar alarms.
And he found that people vary quite a lot in the amount of spontaneous activity. Something that people have also called fidgeting and this component is very strongly genetically determined since it's a familial trait. Ravison, who now heads obesity research at Eli Lilly, says this inherited trait apparently affects the part of the nervous system responsible for involuntary activities such as heart rate. So even though it's potentially a great way to burn calories, people probably can't rev it up consciously.
| 