Effects of Snack Intake on Appetite, Affect and Attention

To test the hypothesis that snacks eaten in the afternoon influence appetite, affect and performance on a simple attention task, an experiment was conducted using a dose-response design. Thirty male volunteers attended the laboratory on five occasions to consume a standard lunch and then to eat a snack three hours later varying in size and carbohydrate/fat content. The effects of consuming four snacks of increasing energy content (124, 274, 424 and 724 kcal) on ratings of hunger, fullness, appetite and mood as well as reaction time and accuracy in a perceptual discrimination task were investigated. Although appetite variables were responsive to the dose-response manipulation, mood and performance were only weakly influenced by snack intake. Lunch produced a greater impact on mood than snack consumption. The larger snacks decreased fatigue and only marginally improved reaction time. It is concluded that when level of deprivation, sensory, hedonic and expectancy effects were controlled, snack intake produced relatively subtle effects on mood and attention.