Following a low-carbohydrate diet such as that popularized by the Atkins Diet may have a detrimental effect on cognitive performance, new research suggests.
Holly A. Taylor, professor of psychology at Tufts University, and colleagues studied 19 women aged 22 to 25 to investigate whether eating a low-carbohydrate diet would have any impact upon cognition. Participants were asked to follow one of two diets plans: a low-carbohydrate (LC) Atkins-type diet, or a macro-nutrient reduced-calorie diet as recommended by the American Dietetic Association (ADA). Nine chose the LC diet, which restricted carbohydrates to no more than 20 grams a day – 110 grams less than the recommended daily intake of 130 grams, whilst 10 chose the ADA diet. Cognitive tests were conducted 72 hours before participants begun the diet, and 48-hours and one week into the diet. Tests were also carried out two and three weeks after participants stopped restricting their carbohydrate intake.
Results showed that participants following the LC diet exhibited a gradual decrease on the memory-related tasks compared with ADA dieters. Participants following the LC diet also scored poorly on tests of reaction time and visuospatial memory. However, LC dieters did score better than ADA dieters in attention tests, a finding consistent with that of previous studies which have shown that LC diets can improve attention span in the short-term. Scores returned to normal once LC dieters began eating normal amounts of carbohydrate again.
“This study demonstrates that the food you eat can have an immediate impact on cognitive behavior,” said Professor Taylor. “The popular low-carb, no-carb diets have the strongest potential for negative impact on thinking and cognition.”
D’Anci K, Watts KL, Kanarek RB, Taylor HA. Low-carbohydrate weight-loss diets. Effects on cognition and mood. Appetite. 2009;52:96-103.
News release: Low-carb diets can affect dieters’ cognition skills Tufts study compared women’s cognition on low-carb and reduced-calorie diets. Tufts University. December 12th 2008.