RALPH LA FORGE studies the role of exercise in weight loss and is managing director of the Lipid and Disease Management Preceptorship Program at Duke University Medical Center.
Why is it so hard to lose weight just by exercising?
RLF: Unless you're a serious athlete, you just don't burn that many calories. Most people overestimate the amount they've burned during a workout.
If exercise is part of your weight-loss plan, what's the best type to do?
RLF: Aerobic activity is far and away the best, for one simple reason: You burn more calories.
Doesn't strength training build muscle and therefore increase your resting metabolic rate?
RLF: That's actually a myth. You'd have to be totally ripped - like, bodybuilder ripped - to get a noticeable bump in your metabolism. Most people burn about one calorie per kilogram of body weight per minute, whereas a bodybuilder burns about 1.2.
What aerobic activities give you the biggest calorie burn?
RLF: Cross-country skiing - in nature, not on a machine - is the highest. Outdoor exercise is almost always more strenuous. You encounter variable terrain, which makes you work harder. Running comes after skiing, and walking on hills is probably third. In general, you burn more calories doing a weight bearing activity that uses lots of big muscle groups. Swimming and biking usually aren't as good because they're not weight-bearing.
Are you better off doing a long, moderate intensity workout or a shorter, high-intensity one?
RLF: If you want to lose weight, stay at a moderate pace, because you can go longer and it doesn't wipe you out as much. When you do a high-intensity workout - running or cycling so hard that you can't carry on a conversation - you are so tired afterward that you tend to be lazier for the rest of the day. Instead of going shopping, you lie on the couch. People also tend to eat 20 to 25 percent more than normal because they're so hungry.
Don’t you enter a fat-burning zone when you exercise at higher intensities?
RLF: The idea of a fat-burning zone is b.s. In order to burn only fat, you would have to go at such a slow pace that you'd burn only two to three calories per minute. You'd have to walk 50 miles to get a decent workout. It's better to exercise at a moderate pace, so you'll burn some fat and some carbs. Doing that regularly can definitely help you control your weight.
