Low-Carb State of Mind
Does the low-carb diet decrease serotonin in the brain and lead to depression? What's a low-carber to do?
By Brenda Goodman published March 1, 2004 - last reviewed on June 9, 2016
Wurtman, who advocates a diet high in complex carbohydrates for weight loss and stress relief, says her studies on rats have shown a connection between a diet low in carbohydrates and low levels of serotonin—a neurotransmitter that promotes feelings of happiness and satisfaction. In her research, rats placed on a ketotic, or low-carbohydrate, diet for three weeks were found to have lower levels of serotonin in their brains. The same rats binged once starch was reintroduced into their diets.
Wurtman believes that same effect occurs in humans on low-carb diets and leads to pronounced feelings of depression and sadness, even rage. "People feel very angry, and their antidepressants don't work well, either," she says.
Granted, dieting isn't easy no matter how one does it, but many think low-carbohydrate approaches are particularly hard on your happiness. Wurtman goes so far as to call them dangerous for those who already struggle with depression or bipolar disorder.
Other researchers disagree. In fact, Wurtman's assertions are in direct contrast to what advocates of low-carbohydrate diets promise—an end to mood swings and fatigue. Indeed, many who have success on these diets say their moods have never been better.
"It's a very hard effect to sort out," says Frederick Samaha, chief of cardiology at the Veterans Administration Hospital in Philadelphia. In one study by Samaha, he compared a low-carbohydrate diet with a low-fat diet.
"We didn't notice any difference in mood between the two groups. What we found, overall, was that people [on either diet] felt good because they were losing weight and becoming healthier," Samaha says. "But there was a high drop-out rate, around 40 percent, and it may be that those folks left because they didn't see any improvement in their quality of life."
Other researchers believe a low-carb diet may have an adverse effect only on those prone to low moods. Philip Cowen, chief of psychiatry at Oxford University in the U.K., reported in a study published in the British Journal of Psychiatry that the mood problem with low-carb diets was measurable but mild in women fighting depression.
"We routinely use a low-carbohydrate diet, which does produce evidence of changes in brain-serotonin function," says Cowen. "In people with a history of depression—but not in those without—this diet lowers subjective ratings of ‘happy' slightly."
So what is a low-carber to do? Robert Thayer, professor of psychology at California State University, Long Beach, and author of Calm Energy: How People Use Food and Exercise to Regulate Mood, says the best advice is to closely monitor mood after experimenting with food. "If you don't have enough energy to function effectively and meet the demands of your day, that's going to create tension."