For Keeping Weight Off, a Low-Carb Diet Wins

New research finds a low-carb diet may be best to keep weight off.New research finds a low-carb diet may be best to keep weight off.By Marianne Wait, for Sharecare

A calorie is a calorie is a calorie.

Or is it?

A new study has put yet another notch in the belt of the low-carb diet, giving people trying to lose weight or keep it off a new reason to pass on pasta and embrace steak this summer.

In the study, published in the Journal of the American Medical Association, researchers pitted three diets against each other to see which one would help people maintain weight loss over the long term -- often the hardest part of losing weight, in part because a slimmer body burns fewer calories.

One was the classic low-fat fat diet, rich in whole grains, fruits and vegetables and getting 60% of its calories from carbs. The second was a moderately low-carb, low-glycemic index diet getting 40% of its calories from carbs (it replaced some grains and starchy vegetables with good fat and low-glycemic vegetables, legumes, and fruits). The third was an extreme low-carb diet reminiscent of the original Atkins diet, getting 10% of its calories from carbs and a whopping 60% from fat. All contained the same number of calories -- but the results were anything but the same.

Expert Q&A: What is the glycemic index?

Metabolism slowed the most on the low-fat diet and the least on the very-low-carb diet. The difference in total calories burned per day was significant, to the tune of several hundred calories-the equivalent of an hour-long workout. The researchers aren't sure why, though several theories exist.

If all of this makes you want to swear off carbs for good, good luck with that. The study participants stayed on each diet for only a month. Giving up bread, pasta, and even most fruits (what, no watermelon this summer?) long term is a different story altogether.

And if you plan to do any exercise to help melt those pounds away, you may find you need the carbs to keep going. "If you do a lot of exercise, you need carb for fuel," says obesity expert James O. Hill, PhD, director of the University of Colorado's Center for Human Nutrition and cofounder of the National Weight Control Registry.

The best diet to prevent obesity, heart disease, and diabetes.

"We have been studying over 7,000 people in the National Weight Control Registry for over a decade," says Hill. "These people have are maintaining an average weight loss of 70 pounds. Most of them follow a low fat diet and do 60 to 90 minutes a day of exercise. I believe a low-fat diet plus exercise is the best way to prevent weight gain. It is possible to avoid weight gain with a low-carb diet but most people find such diets hard to stick with over the long term."

Expert roundtable: Low-fat vs. low-carb diets

One thing's for sure: The low-fat vs. low-carb debate is sure to smolder longer than those fire-roasted marshmallows you may be giving up this summer.

Marianne Wait is the vice president and executive editor at Sharecare.

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