September 07, 2008
No Sweat
Working out in cold weather will not shiver you into losing weight, neither will sweating in a "hot" yoga class.
Q: Will I burn more calories exercising in hot weather or cold weather?
A: You burn about the same number of calories regardless of the air temperature. When you're sweating it up in one of those "hot" yoga classes or drenched on a summer power walk, it may seem like you're melting away pounds more quickly, but in reality you're just shedding more water than usual. As soon as you take a drink, you replace the water weight. If you don't drink up, you risk dehydration.
Working out in the cold won't rev up your calorie burn, either, unless you're so chilly that you start to shiver. Shivering is an involuntary clenching of muscles designed to generate heat. When your teeth are chattering, and every muscle in your body is tense, you burn nearly four times more calories than usual. And when it's so frigid that in addition to shivering, you're hopping from foot to foot and rubbing your hands together to keep warm, you boost your calorie burn even more. However, this isn't a good reason to go out jogging in February in Fairbanks wearing shorts and a t-shirt. Sure, you'll burn more calories than if you work out properly clothed or indoors on the treadmill, but you'll also risk hypothermia and frostbite.
Q: If I stop exercising, will my muscles turn to fat?
A: No. This myth has prevailed in part because many former athletes who were once buff and brawny begin to resemble Santa Claus as they get older. This doesn't mean that their muscle "turned into fat" any more than it means their muscle has turned into tapioca pudding. Muscle is muscle and fat is fat. You simply can't transform one type of tissue into another.
The former athletes who plump up do so for the same reason everyone else gets fat: Their muscles gradually shrink from neglect while their body-fat stores expand from consuming excess calories. If you stop exercising (and we don't recommend it!), the muscle you've developed will slowly atrophy. If you cut back on calories accordingly, you probably won't gain fat, but you certainly won't look as firm as you did in more active times. If you happen to live a lifestyle that's completely sedentary, and you frequently utter the words "I'll have seconds," you're likely to pack on the pounds.
More Q&A:
About Our Expert: Suzanne Schlosberg is the author of The Ultimate Workout Log and The Essential Fertility Log and coauthor of Fitness for Dummies and The Fat-Free Truth. She's a health and fitness writer living in Bend, Oregon.
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