Physical Education

Unit 1

1.2.3.Activity and Weight Management
If you burn more calories than you consume, then you'll shed pounds. For every extra 3,500 calories you spend, you'll drop one pound. Do strenuous exercise, and you'll burn calories in a hurry. And you can burn the same number of calories with gentler activity: You just have to do it longer and/or more often.
If you're not familiar with the number of calories burned during exercise, you may be discouraged when you first learn about it. For instance, if you weigh 150 pounds and go on a brisk, 1-mile walk for 20 minutes, you'll expend about 100 calories, considerably short of the 3,500 calories needed to drop a pound.
But such efforts add up. If you expend an extra 300 calories a day through activity and reduce your dietary intake another 200 calories, then by the end of a week, you'll have a calorie deficit of 3,500, comparable to a one-pound weight loss. This is precisely the kind of gradual success that experts recommend for long-term weight management.
Exercise also has other body-slimming effects. It builds muscle and displaces fat. A given volume of muscle weighs more than the same bulk of fat. So your bathroom scale may not record dramatic changes, but your clothes will be looser, and you'll have a trimmer body shape.
Because exercise builds muscle, it may also help counter a problem caused by dieting. When you reduce calories, your body metabolism may slack off and burn calories more slowly. This makes further weight loss more difficult. But some research suggests regular activity helps correct this slowdown and makes it easier to keep shedding pounds.