I'm watching you. Awareness that food consumption is being monitored is a demand characteristic in eating-behaviour experiments

Eating behaviour is often studied in the laboratory under controlled conditions. Yet people care about the impressions others form about them so may behave differently if they feel that their eating behaviour is being monitored. Here we examined whether participants are likely to change their eating behaviour if they feel that food intake is being monitored during a laboratory study. In Study 1 participants were provided with vignettes of typical eating behaviour experiments and were asked if, and how, they would behave differently if they felt their eating behaviour was being monitored during that experiment. Study 2 tested the effect of experimentally manipulating participants' beliefs about their eating behaviour being monitored on their food consumption in the lab. In Study 1, participants thought they would change their behaviour if they believed their eating was being monitored and, if monitored, that they would reduce their food consumption. In Study 2 participants ate significantly less food after being led to believe that their food consumption was being recorded. Together, these studies demonstrate that if participants believe that the amount of food they eat during a study is being monitored then they are likely to suppress their food intake. This may impact the conclusions that are drawn from food intake studies.