Do Carbs Make You Fatter?

Researchers have repeatedly found that all calories, no matter what food they come from, produce exactly the same amount of energy. But a recent preliminary study at the Harvard School of Public Health tantalizingly hints otherwise. Controlling every bite of food subjects ate, researchers discovered that low-carb dieters lost more weight than low-fat dieters despite consuming an extra 300 calories per day—or 25,000 additional calories over the course of 12 weeks, which, mathematically speaking, should have made them lose about seven fewer pounds. The experiment was too small to be considered definitive (though, naturally, it was reported at great length in the press), and the researchers are now designing a larger study to see if the results will hold up.

Other studies, including one by Brehm, suggest that people on low-carb diets do shed pounds faster than low-fat dieters. The longest study to date, however, showed that while Atkins-type dieters lost more weight than low-fat dieters in the first six months, by the end of a year there was no discernible difference between the two groups.