The influence of meal composition on post-lunch changes in performance efficiency and mood.

Effects of meal composition on post-lunch changes in performance efficiency and mood were examined. Lunch had an effect on mood, with subjects feeling more lethargic, feeble, clumsy, muzzy, dreamy, bored and mentally slow after the meal. However, the composition of the lunch did not influence this effect. High starch and high sugar meals slowed reactions to visual stimuli presented in the periphery, whereas consumption of a high protein lunch was associated with greater susceptibility to distraction from stimuli close to the target. These results show that protein and carbohydrate meals affect different aspects of attention. That is, the behavioural effects of a meal depend both on its composition and on the particular nature of the activity being carried out.