10 Reasons Why Exercise Makes You Thin (Or Why TIME Magazine Got It Wrong)

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Six experts weigh-in on how and why exercise is a critical weight-loss strategy.

By Holly Pevzner

Thinking TIME magazine's recent article, "Why Exercise Won't Make You Thin," is giving you a good excuse to skip your workout in favor of a beer or 3? Think again. We've always known that exercise is critical to losing weight and maintaining a healthy weight, especially when paired with healthy eating habits. But just to be sure, we double-checked with six experts around the country - here's what they said.

Countless studies, numerous experts who study exercise, and the millions of people who have lost weight all attest to the fact that working out works. "Exercise is absolutely essential for dropping weight and maintaining weight loss," says FITNESS advisory board member Michele S. Olson, Ph.D., professor of exercise science at Auburn University Montgomery. Here's what exercise does-and how it does it-to keep you healthy, happy and slim.

1. Exercise zaps belly fat.

It's the easiest way to beat the bulge, period. "Regular moderate to high intensity aerobic exercise has the greatest impact on reducing ab fat-the dangerous fat that ups your risk of diabetes and heart disease," says Olson. Exercise is the ultimate middle manager because it lowers cortisol levels, a hormone that has been linked to ab fat. In fact, women with the most cortisol in their system have higher BMIs and bigger bellies than those with moderate amounts of the hormone, found a University of California at San Francisco study.

2. Exercise controls calories.

"It's pretty simple: You need to burn more calories than you consume in order to lose weight," says Nancy Snyderman, M.D., a FITNESS advisory board member, editor-in-chief of BeWell.com and chief medical editor for NBC news. Regular exercise blasts excess calories that would otherwise be stored as fat. "Plus, you continue to burn calories even in the hours following your workout," says Dr. Snyderman.

3. Exercise keeps lost pounds MIA.

"Ninety percent of people who have successfully lost weight and kept it off for a year do about an hour of physical activity a day," says John Porcari, Ph.D, a FITNESS advisory board member and a professor of exercise and sports medicine at the University of Wisconsin-La Crosse. Exercise is even prescribed by docs for people who have undergone weight loss surgery to help them hold onto their newly thin figures.

4. Exercise boosts metabolism.

Yes, you'll lose fat when you diet without exercising, but you'll also lose muscle, which means you'll burn fewer calories. The more muscle you have, the higher your metabolism and the more calories you'll torch.

5. Exercise trims inches.

The number on the scale doesn't tell the whole truth, says FITNESS advisory board member, Jari Love a certified personal trainer and fitness DVD star: "When you shed fat and gain muscle you may lose inches and drop sizes without losing actual pounds." For instance, if you gain 3 pounds of lean muscle and lose 4 pounds of fat, you've actually experienced a 7-pound improvement in your body condition, despite the scale only showing 1 pound of weight loss.

6. Exercise curbs emotional eating.

"Working out has been proven time and time again to help regulate mood, which has a direct effect on people who eat when they're stressed or upset," says Robert E. Thayer, Ph.D., a professor of psychology at California State University, Long Beach. Translation: When you're already in your happy place you don't need Ben & Jerry to lead the way.

7. Exercise creates a healthy chain reaction.

There's a reason you find juice bars at the gym: "Healthy habits tend to cluster together," says Boston-based psychologist, Eric Endlich, Ph.D. "When people make positive changes, like getting more exercise, they tend to work on other health improvements as well, such as eating better." The result? Weight loss.

8. Exercise brings on the fun.

Let's face it: Rock-climbing is way more exciting than eating a celery stick. That's why it's easier to be active to stay slim than to maintain a strict diet. "If you look at people who incorporate exercise successfully in their lives, they've found something they truly enjoy," says Dr. Snyderman.

9. Exercise stops hunger.

People who exercise and diet are actually less hungry than those who only diet, according to a study in the journal Obesity. Bonus: Your self-restraint is higher, too.

10. Exercise ups energy.

Regular physical activity increases stamina by boosting the body's production of energy-promoting neurotransmitters, studies show. That pep gives you even more motivation to get moving and shed pounds. When was the last time diet alone did all that?