In Brief

Low-carb dieting: Slimmer but sadder?

Low-carb diets have done well in some head-to-head comparisons with other diets. And no matter what the diet, shedding a few pounds usually makes people happy.

But there's some research suggesting that Atkins-like diets (low in carbs, high in fat and protein) could make people's moods a little darker even if their bodies end up a little lighter. Carbohydrates promote the synthesis of serotonin, a neurotransmitter that seems to play a significant role in mood control. Some evidence suggests that avoiding carbs — and gorging on fat and protein instead — could reduce serotonin concentrations, giving some folks a case of the low-carb blues. And when diets have been tested for a short time (three weeks) in physically active people without a weight problem, low-carb eating has led to more fatigue and bad moods than high-carb eating.