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The Rumor: Certain foods affect your metabolic rate and how quickly you burn through calories

You know that friend of yours who can eat whatever she wants and still looks great in a bikini? The same one who apologetically says, "I guess I have a high metabolism" -- while stuffing a cupcake in her mouth and sipping on a milkshake?

Stop hating. She was likely blessed with a high metabolism: Part of our individual metabolic rates -- the rates at which our bodies burn food for energy -- is preprogrammed in our genes. The higher your metabolism, the more calories you can consume without gaining weight.

"Your metabolism is how your body burns fuel and burns energy," says certified personal trainer Mark MacDonald, author of Body Confidence. "We should care about it because it determines our weight. It's going to determine our appetites, and it really determines our body fat levels as well. So if your metabolism is slower, then you're not going to burn fuel as fast, and that's going to cause you to store body fat. If you have a fast metabolism, that's going to allow you to burn more energy."

The Verdict: Avoiding foods that slow metabolism is as important as incorporating ones that improve it

The good news is, anyone can improve his or her metabolic rate by choosing the right foods and avoiding the wrong ones. A growling belly signals falling blood sugar, and that's bad for metabolism. To avoid this, MacDonald recommends eating five times a day.

"Every single time you miss a meal, your blood sugar drops [and] your body over-releases a hormone that makes you burn muscle, not fat," says MacDonald. "That's why dieting fails people long-term: because it creates a core deficit that makes you burn muscle. Then you go into that next meal not craving chicken or tuna; you crave carbohydrates. That spikes your blood sugar... and it makes you over-release insulin and store fat." The more fat, the lower your metabolism.

To help stop the vicious cycle, add high-fiber foods, such as fruits and vegetables, to your diet. They're low in calories and the fiber is a natural colon-cleanser -- which helps keep the digestive system moving smoothly. "Your colon is 18 feet long; it takes a lot of energy to push fiber all the way through," says Dian Griesel, Ph.D., author of TurboCharged: Accelerate your Fat Burning Metabolism, Get Lean Fast and Leave Diet and Exercise Rules in the Dust. "The more your body's working naturally for you, the more your metabolism's staying high."

Need a snack? Step away from the pretzels and instead opt for a combination of protein, fat and carbohydrates, says MacDonald. A cheese stick (protein and fat) and piece of fruit (carbohydrate) is a good example. Eating those together will help stabilize your blood sugar, and you'll avoid the dips and spikes that wreak havoc on metabolism. If your blood sugar surges, your body stores the excess sugar as fat. If it dips, your body thinks it's in starvation mode and burns muscle. And the more muscle you have, the higher your metabolism.

Before each meal, drink two glasses of icy cold water, suggests Griesel. "You'll eat less, and your body will be a little chilled, so it will start working harder to stay warm," she says. Being properly hydrated also helps grease the wheels of your digestive system, encouraging food to be metabolized more quickly.

According to MacDonald, most people are sensitive to one or all of the following foods: soy, dairy and gluten (the protein found in wheat, rye and barley). If that's the case for you, then when these foods reach the intestines, they cause inflammation that slows down digestion. "If your fuel isn't being broken down cleanly," he says, "it affects your performance: metabolism, gas, bloating, weight gain -- all of that."

Another factor? Sodium. If a food comes in a box or can and has a long list of ingredients, many unpronounceable, chances are it's a processed food packed with preservatives and sodium. 

One of the best ways to boost metabolism is to build muscle. "Get up every two hours and stretch for one minute," says Griesel. "Get into plank position, do some push-ups, squat against a wall. Your muscles will respond quickly. And you're boosting your metabolism because not only are you helping release your natural human growth hormone -- which is good for your longevity and your musculature -- but you're also causing more calories to get burned and therefore raising your metabolism."


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