How Many Calories Are You Using -- and Other Burning Questions
by Carol Krucoff
BodyWorks


If a cookie contains 100 calories, anyone who eats it consumes 100 calories.

But the other side of the energy equation isn't that simple. When it comes to burning off calories, people who do the same activity at the same pace for the same amount of time can burn vastly different numbers of calories, depending on their size. For example, if a family of three jogs side-by-side for 30 minutes, the 175-pound father will burn 400 calories, the 130-pound mother will burn 300 calories and the 65-pound child will burn 180 calories.

"Larger people burn more calories than smaller people, particularly with activities like walking or stair climbing where they have to carry their own weight," says Robert McMurray, professor of exercise and sports science at the University of North Carolina at Chapel Hill. Exercisers are often mislead by workout equipment or charts that don't factor in weight when they proclaim how many calories are being burned by an activity, he says. If an exercise machine or chart calculates the calories burned by an "average" 150-pound person, the results would be "vastly inaccurate" for much larger or smaller exercisers.

In addition, leaning on the hand-rails of a stair climber or keeping a "death grip" on the treadmill railing will greatly decrease your caloric expenditure, says exercise physiologist Steve Farrell of the Cooper Institute for Aerobics Research in Dallas. "The machine is assuming that your legs are carrying your entire body weight," he notes. "But if you're supporting yourself on the handles, you're actually burning about 20 to 30 percent fewer calories than the machine indicates."

Knowing how many calories you're burning during activity can be important if you're trying to lose weight, since the "general rule of thumb for weight loss is to create a 300- to 500-calorie deficit each day," Farrell says. This means, consume 300 to 500 fewer calories than you expend.

Half of this "calorie deficit" should come from eating less and half should come from exercising more. "We generally advise people who want to lose weight to expend at least 250 calories more each day than they have in the past," he says. "Additionally, they should eat 250 fewer calories than they've been eating."

Calorie burning is just one of four main reasons why "regular exercise is the single best predictor of whether an overweight person will lose weight and keep it off," says Yale University psychology professor Kelly Brownell, who has done extensive research on obesity and eating disorders. "People lose more weight than you can explain by the calories burned from exercise," Brownell notes. Exercise also boosts weight loss because it:

Builds muscle. Muscle tissue is the most metabolically active tissue in the body, so people with more muscles burn more calories, even at rest.

Revs up the metabolism. The metabolic rate rises during physical activity and stays elevated for a significant period of time after exercise is finished.

Affects psychological factors. Exercise helps boost self-esteem and body image, reduce depression and relieve stress. "This can give people more psychic strength to adhere to a diet," says Brownell, who believes "most of the action" in exercising for weight loss comes from this psychological dimension.

To lose weight, "do anything you can to be more active--even if it's just parking in the farthest space and walking an extra 50 yards," Brownell says. "That's like making a deposit in your self-esteem bank because you know you've done something good for yourself." And having a high "self esteem bank balance," he says, can help people gain the willpower and commitment to adhere to healthy eating habits for life.
© Carol Krucoff, 1998. All rights reserved.

CALORIES BURNED DURING 30 MINUTES OF ACTIVITY

TYPE OF ACTIVITY 130-pound adult 175-pound adult 60-70 pound child
Cycling 180 240 120
Swimming 210 300 140*
In-Line Skating 210 280 128
Softball 120 160 70*
Aerobic Dance 180 240 110*
Jogging 300 400 180
Hiking (20-pound pack) 280 336 185
Tennis 180 270 110*
Martial Arts 300 420 180*
Skiing 240 330 150*
Walking 130 180 80
Canoeing 80 105 45*
Bowling 170 231 90*
Weight Lifting 210 240 125
Frisbee 180 240 100*

*Estimate based on adult data, no data on children exists.

Chart courtesy of Professor Robert McMurray, University of North Carolina at Chapel Hill