MOOD AND COGNITIVE PERFORMANCE EFFECTS OF ISOCALORIC LUNCHES DIFFERING IN FAT AND CARBOHYDRATE CONTENT

Eighteen subjects consumed low-fat/high-carbohydrate (LFHC) (29% fat, 54% carbohydrate, 15% protein), medium-fat/medium-carbohydrate (MFMC) (45% fat, 42% carbohydrate, 12% protein), and high-fat/low-carbohydrat e (HFLC) (62% fat, 24% carbohydrate, 13% protein) isocaloric lunches i n random order an 3 separate days. The MFMC lunch was similar in energ y and macronutrient composition to the habitual lunchtime intake of th e subjects. A battery of cognitive performance tasks together with moo d and appetite ratings were carried out before and during the 3 h afte r lunch. Results showed longer reaction times following the LFHC and H FLC lunches compared to the MFMC lunch, which produced an improvement in performance on this task. In addition, subjects rated themselves as more drowsy, uncertain and muddled, and less cheerful after the LFHC and HFLC lunches compared to the MFMC lunch, and as less tense after t he LFHC meal. These findings indicate that the macronutrient content o f lunch can have significant acute effects on subsequent mood and perf ormance. In particular, higher than usual proportions of fat or carboh ydrate produced a relative impairment of cognitive efficiency.