Scientists found carbohydrates help boost the production of serotonin which controls emotions and a shortage can lead to mood swings and depression.

"[Serotonin is] essential to keep your moods regulated," said lead researcher Dr. Judith Wurtman of the Massachusetts Institute of Technology.

Her team discovered the brain makes serotonin only after a person consumes sweet or starchy carbohydrates in combination with very little or no protein. So while a meal of pasta allows the brain to make serotonin, eating chicken and potatoes actually stops it from being produced.

This explains why people can still feel hungry after chowing down on a large steak - because, while their stomachs are full, their brains are not making enough serotonin to stop their appetite.

A lack of carbohydrates also tends to have more impact on women than men, because women have less serotonin in their brains, the study found.

"When you take away the carbohydrates, it's like taking away water from someone hiking in the desert," Wurtman told the BBC.

Stuart Trager of the Atkins Physician Council said clinical research contradicted the MIT findings.

He pointed to one study that showed controlling carbohydrate intake improved the mood of 51 percent of those who took part in lab tests.