Published: August 24, 2009 08:59 am      

Low-carb diet impairs mental cognition

Atkins and other low-carb dieters are likely to suffer decreased mental performance, according to a recent study at Tufts University in Boston. Scientists found that participants performed worse on mental tests after just a week on a low-carb diet.

One of the most popular low-carb diets is the Atkins Diet, which eliminates carbohydrates such as bread, potatoes and sugar but allows protein and fat. Some fruits and vegetables also are restricted. The Atkins Diet proposes that the body burns more calories through an elevated metabolic rate than normal diets. The recent study, however, suggests that there is a mental disadvantage to counterbalance whatever physical gains might be achieved.

Holly Taylor, lead researcher in the study, warned that such a diet can have a negative impact on memory and thinking.

“The study demonstrates that the food you eat can have an immediate impact on cognitive behavior. The popular low-carb and no-carb diets have the strongest potential for negative impact on thinking and cognition,” she said.

The study followed 19 women aged 22 to 25 who were on either a low-carb diet or a low-calorie balanced diet. After only one week the 10 women on the low-carb diet performed more poorly on mental tests than those on the conventional diet. The women were tested on their short- and long-term memory, visual attention and spatial memory, the part of the memory that stores information about a person’s environment. Those on the low-carb diet showed a gradual decrease in mental tasks compared to the low-calorie dieters. Reaction time also was slower and their visual memory was not as good.

“Although this study only tracked participants for three weeks, the data suggests that diets can affect more than just weight. The brain needs glucose for energy, and diets low in carbohydrates can be detrimental to learning, memory and thinking,” Taylor said.

The research, published in the journal Appetite, found there was no difference in the hunger levels of the women. Scientists believe that low-carb diets decrease the amount of glucose available to the brain and what is needed for nerve transmission.