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Low-fat or low-carb? New study settles debate

By Tracie Snowder, | Posted - Aug 14th, 2015 @ 8:29pm



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SALT LAKE CITY — In the never-ending battle of low-carb versus low-fat diets, scientists may have just settled the debate — and discovered there really shouldn't be one.

The new study from the National Institutes of Health found that low-fat diets led to slightly more weight loss. The very-controlled study took 19 obese adults and kept them in an inpatient center for two weeks at a time. The participants also exercised on a treadmill for one hour each day.

For the first five days, participants were kept on a normal diet consisting of 50 percent carbs, 35 percent fat and 15 percent protein. Then participants were put on either a low-fat or low-carb diet for six days that was 30 percent lower in calories. Participants had a few weeks' break, then came back and did the opposite diet of what they had done before.

On average, participants in the low-fat diet group lost 463 grams of fat versus the 245 grams lost on the low-carb diet. Researchers estimate that if the diets were to continue, participants on the low-fat diet would lose six more pounds on average within six months.

But is that enough information to declare low-fat diets the winner? Not really, said study author Kevin Hall. While there's no real frontrunner, the study does show that diets don't have to be low-carb to be effective.


That (low-carb) theory, as it stands — that very strong claim — is certainly not true. All calories weren't exactly equal when it came to losing body fat ... but they were pretty close.

–Kevin Hall, study author


"That theory, as it stands — that very strong claim — is certainly not true," Hall told NPR. "All calories weren't exactly equal when it came to losing body fat ... but they were pretty close."

David L. Katz, founder of the Yale University Prevention Research Center, told Forbes.com he is impressed with the quality and outcome of the study, which "robustly belies the recently popular claim that only carbohydrate counts for weight loss."

"In my view, this is a reality check," Katz told

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