Situational effects on meal intake: A comparison of eating alone and eating with others.

Eating in competition with other tasks has been shown to increase food intake, particularly when tasks are cognitively demanding. To test the hypothesis that social facilitation of eating occurs, in part, as a function of distraction which impairs the ability to self-monitor, eating with others was compared with eating alone or in front of the television. Using a repeated measure within-subjects design, thirty-seven participants (21 males) visited the laboratory 4 times to eat a buffet-style lunch ad libitum. All eating episodes were filmed. Energy intake (EI) was measured when participants ate alone (A), ate alone while watching TV (B), ate with two same sex strangers (C), and ate with two same sex friends (D) in a counterbalanced order. EI was significantly enhanced by presence of familiar others (D: 4565+/-272 kJ, p < 0.001) and watching TV (B: 4350+/-252 kJ, p < 0.05) compared to baseline (A: 3861+/-200 kJ). Length of eating episode correlated significantly (p < 0.05) with EI, however, amount of time spent eating and looking at food differed by condition with a greater percentage of time focussed on food during baseline (p < 0.001). Eating with friends increased EI by 18% and eating in front of the TV increased EI by 14% relative to baseline. Engaging in conversation or watching TV draws attention away from the eaten food and can stimulate food intake. However, since eating with strangers also drew attention away from food but did not result in increased intake, social facilitation effects are not simply due to distraction. Thus food intake can be enhanced when attention to food and self-monitoring are impaired during distraction, however, this effect is moderated when eating with strangers.