Carbs vs. low fat diets: New study says its all about the calories

This low carb vs. low-fat diet debate isn't as fun as the less filling, great taste Miller Lite commercials but it's just as spirited.

The argument is that low-carb diets are necessary to burn off body fat because the body’s insulin levels drop, a necessity to burn fat.

Kevin Hall at the National Institute of Diabetes and Digestive and Kidney Diseases wanted to test this out. So he and colleagues recruited 19 obese volunteers  with an average weight of more than  230.

And Hall was serious. He kept his subject in the lab 24 hours, seven days a week so scientists could keep them on an exact diet. One group got a low-carb diet that reduced their calorie intake by 30 percent. The other group went on a low-fat diet that reduced calories by the same margin.

For two weeks they were kept in a lab around the clock, where scientists could provide them a precise diet. One group got a low-carb diet that reduced their total calories by 30 percent. Another group went on a low-fat diet that also reduced their total calories by 30 percent. Then, after a few weeks of rest, the two groups switched diets.

Hall tells the journal Cell Metabolism, cutting carbs did work exactly as the theory predicts with the average participants losing about a pound of fat over two weeks and about four pounds total.

“We cut the carbohydrates, insulin went down, and fat burning went up, exactly the way that theory predicts, and people lost fat,” Hall says.

But the study also showed that the low-carb, low-insulin conditions were not necessary to shed body fat. Those on the low-fat diet also led to the loss of about 1 pound of body fat.

“That theory, as it stands — that very strong claim — is certainly not true,” he says.

Should you eat pizza on a diet? What do you think? But if you do, limit it to one slice. It’s all about counting calories, a new study says. (Photo courtesy of Creative Commons)

Instead, his evidence favors those who say if you want to lose body fat, total calories matter most.

“All calories weren’t exactly equal when it came to losing body fat … but they were pretty close,” he says.

So, I guess, you can have that pizza – just don’t eat the whole pie.

You can read the whole NPR piece here.