MEDFORD/SOMERVILLE, MA—A new study from the psychology department at Tufts University shows that when dieters eliminate carbohydrates from their meals they performed more poorly on memory-based tasks than when they reduce calories, but maintain carbohydrates. When carbohydrates were reintroduced, cognition skills returned to normal.
"This study demonstrates that the food you eat can have an immediate impact on cognitive behavior," explains Holly A. Taylor, professor of psychology at Tufts and corresponding author of the study. "The popular low-carb, no-carb diets have the strongest potential for negative impact on thinking and cognition."
Study participants included 19 women ages 22 to 55 who were allowed to select the diet plan they preferred—either a low-carbohydrate diet or a low-calorie, macronutrient balanced diet recommended by the American Dietetic Association. Nine women chose a low-carbohydrate diet and 10 selected the low-calorie diet.
The 19 dieters completed five testing sessions that 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.
