A low-carbohydrate diet is used to promote weight loss, but it may offer less benefit in terms of the rate of cognitive processing. In overweight and obese patients, following an energy-restricted dietary plan for weight loss is associated with improvements in mood, regardless of macronutrient composition. However, its effect on psychological function is largely unknown. Researchers from the Commonwealth Scientific and Industrial Research Organisation-Human Nutrition, in Adelaide, Australia compared mood and cognitive function in overweight or obese, but otherwise healthy, men and women who were aged between 24 and 64 years. For over eight weeks, the participants followed one of the two diets of similar caloric and macronutrient content. The low-carbohydrate diet contained 35 per cent total protein, 61 per cent total fat (20 per cent saturated fat) and 4 per cent total carbohydrate. The high-carbohydrate diet consisted of 24 per cent total protein, 30 per cent total fat (less than 8 per cent from saturated fat) and 46 per cent total carbohydrate. The findings did not reflect any mood changes among the 93 participants consuming either the low- or high-carbohydrate diet for the study duration. However, a small between-group difference was found favouring the high-carbohydrate dieters in the speed in which participants performed intelligence and reasoning tests. The findings thus suggest that very low carbohydrate diets may offer less benefit than a high carbohydrate diet for improving cognitive function. However, further research is warranted to determine whether or not similar outcomes can be achieved with similar diets for longer duration.
The American Journal of Clinical Nutrition,
September 2007