According to a January 2010 report in the "Journal of the American Medical Association," almost 34 percent of all Americans are obese. But despite the billions of dollars overweight individuals spend on fad diets, diet foods and diet pills in hopes of slimming down, the bottom line is that if you want to lose weight, you must burn more calories than you eat, and the best way to burn more calories is to exercise.
Significance
Excess body fat has been linked to most major health problems, such as coronary heart disease, high blood pressure, osteoporosis, diabetes, arthritis and even certain types of cancer. Numerous studies have linked obesity to a decrease in longevity and poorer health overall.
Definition
A calorie is a unit of energy usually associated with food, but it also applies to anything containing energy. In terms of food, the calories you see on a food package are actually kilocalories, with 1,000 calories equivalent to 1 kilocalorie. Therefore, a can of soda containing 200 food calories contains 200,000 regular calories, or 200 kilocalories. The same terms apply to exercise; when a chart says you burn 100 calories for every mile you jog, it means 100 kilocalories. Most health and fitness experts say calorie instead of kilocalorie.
Measures
Each pound of fat your body stores represents 3,500 calories of unused energy, so to lose 1 lb., you need to create a calorie deficit of 3,500 calories by eating 3,500 fewer calories than you need or adding 3,500 calories worth of exercise over a period of time. When you see charts with estimates for number of calories used during a physical activity, they are based on experiments measuring the amount of oxygen consumed during a specific bout of exercise for a certain body weight. High-intensity activities burn more calories than moderate-intensity exercises.
Benefits
Exercise not only has the benefit of weight loss, but when you burn more calories, you also build muscle tissue that uses calories at a faster rate than body fat. Exercise also helps to reduce inches off your waist and other areas, resulting in a firmer, leaner body, even if your weight stays the same. Some studies have shown that your metabolic rate stays elevated for some time after vigorous exercise, causing you to use even more calories throughout your day.
Time Frame
For most healthy adults, the Department of Health and Human Services recommends that you get at least two hours and 30 minutes a week of moderate aerobic activity, such as brisk walking or swimming, or one hour and 15 minutes a week of vigorous aerobic activity like running, preferably spread throughout the week. If you want to lose weight, however, you will need to increase your activity even more, preferably at least 60 minutes daily.
Types
Any kind of physical movement will burn calories, but the type that uses the most energy is aerobic exercise, the term aerobic being derived from the Greek word meaning "with oxygen," or an activity that makes you breathe more heavily. An aerobic exercise, such as jogging at a rate of 5 miles per hour, burns 728 calories in 60 minutes for a person weighing 200 lbs., whereas walking at a slow pace of 2 miles per hour burns only 228 calories. The Mayo Clinic and many other sites have tables that can help you determine the rate of calorie burn depending upon the activity, the intensity and your weight.
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