Nineteen participants took part in the study. Each participant could choose between a low-carbohydrate diet or a low-calorie, macronutrient balanced diet recommended by the American Dietetic Association. Conveniently, of the nineteen female participants who took part, nine chose a low-carbohydrate diet and ten selected the low-calorie diet.

"Although the study had a modest sample size, the results showed a clear difference in cognitive performance as a function of diet," claimed Taylor.

The dieters completed five testing sessions at various pointst during the 3 week study, the tests assessed cognitive skills, including attention, long-term and short-term memory, and visual attention, and spatial memory.

Low-carb dieters showed a gradual decrease on the memory-related tasks compared with the low-calorie dieters. Reaction time for those on the low-carb diet was slower and their visuospatial memory was not as good as those on the low-calorie diet. However, low-carb dieters actually responded better than low-calorie dieters during the attention vigilance task. Researchers note that past studies have shown that diets high in protein or fat can improve a person's attention in the short-term, which is consistent with the results in this study.

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