Do Low Carb Diets Cause Depression?

There's been a persistent myth about low-carb diets making people depressed and foggy-brained, and up to now, not a whole lot of research on it.

But in a study just published in the September issue of the American Journal of Clinical Nutrition, researchers from Australia decided to investigate diet and mood. They put 93 overweight or obese men and women on one of two diets- high-carb low- fat, or low-carb high-fat. The diets ranged from 1400-1700 calories a day, approximately 30% less than what the participants were used to. The study lasted 8 weeks.

At the beginning of the study- and for every 2 weeks afterwards-- participants were weighed, and also tested on three different standardized assessments of mood. They were also tested on memory and "Speed of cognitive processing", a measure of how quickly they could perform simple mental tasks.

Here's what the researchers found: Not surprisingly, the low-carb group lost significantly more weight. But everyone in both diet groups improved in mood, with no significant differences seen between the two groups. Memory was also the same in both groups, and both groups improved in "speed of cognitive processing" though the low carb group improved slightly less. (The researchers admitted that more studies were needed to see if that minor finding would be replicated.)

So do low carb diets make people depressed? The answer- like most answers- is "it depends". Any diet can affect mood, (in some people more than others), and the exact outcome will depend on a host of circumstances way too complex and intertwined to reduce to a single simplistic statement. Plus, how you feel the first two days of a diet isn't necessarily how you feel two weeks into it. That said, the current study gives the lie to the myth that "low carb diets causing bad moods". This study showed quite the opposite.

The low carb group improved in mood and overall well-being and lost more weight on top of it!