There are an estimated 59 million people in the US on the Atkins diet, according to recent data from the Valen group, and this looks set to grow with rising obesity rates.
Judith Wurtman, director of the Program in Women's Health at the MIT Clinical Research Center in the US, and colleagues have found that a lack of dietary carbohydrates stops the brain from regulating serotonin, a chemical that elevates mood and suppresses appetite. Only carbohydrate consumption naturally stimulates production of serotonin.
"When serotonin is made and becomes active in your brain, its effect on your appetite is to make you feel full before your stomach is stuffed and stretched," said Wurtman. "Serotonin is crucial not only to control your appetite and stop you from overeating; it's essential to keep your moods regulated."
Antidepressant medications are designed to make serotonin more active in the brain and extend that activity for longer periods of time to assist in regulating moods. Carbohydrates raise serotonin levels naturally and act like a natural tranquilizer.
MIT researchers have discovered that the brain makes serotonin only after a person consumes sweet or starchy carbohydrates. But these carbohydrates must be eaten in combination with very little or no protein, the researchers said.
This can explain why people may still feel hungry even after they have eaten a large steak. Their stomachs are full but their brains may not be making enough serotonin to shut off their appetites, explain the researchers.
Women have much less serotonin in their brains than men, so a serotonin-depleting diet will make women feel irritable.
"There are people we call carbohydrate cravers who need to eat a certain amount of carbohydrates to keep their moods steady," said, Wurtman, co-founder of a weight-management company, Adara. "Carbohydrate cravers experience a change in their mood, usually in the late afternoon or mid-evening. And with this mood change comes a yearning to eat something sweet or starchy."
According to Wurtman, if the carbohydrate craver eats protein instead, he or she will become grumpy, irritable or restless. Furthermore, filling up on fatty foods like bacon or cheese makes you tired, lethargic and apathetic.