Is weight loss easier in hot weather?

Myth: You can lose more weight in warm weather.

Facts: Well, sure you can—if you exercise more and eat less as the mercury climbs. But if you maintain the same habits as winter fades, don’t plan on magically dropping pounds.

The perception that we lose more weight when it’s warm out may come from the fact that we sweat more when we’re hot. But losing weight via sweat means losing water, not fat, says Walter R. Bixby, associate professor of exercise science at Elon University in North Carolina. Lost water weight comes back fast—and dehydration can be dangerous—so extreme sweating is not a sound way to manipulate the scale.

In fact, it’s the season of sweaters—not sweating—that can be more conducive to slimming down. Although the weather isn’t a confirmed factor in weight management, you’re more likely to burn extra calories when it’s cold out, explains Bixby, because your body works to keep its temperature constant. “Your body fights harder to stay warm than it does to cool off,” he says. So exercising outdoors on a cold day may burn incrementally more calories than the same activity on a hot one.

But like squirrels, many people seem to pack on pounds in the winter and shed them come spring. That’s likely due to increased activity when the weather’s nice. Surprisingly, though, Americans who live in places where you can exercise outdoors nearly year-round aren’t necessarily slimmer than the rest. According to a 2008 report, Mississippi has the highest rate of obesity in the country. The state with the lowest obesity rate? Colorado.

Beth Goulart is a journalist based in Austin, Tex.