Here is a handy tip for those who want to eat less: watching exercise ads on TV could very well reduce food intake in the meal after.
'Exercise and food are linked in the mind of the consumer, the most familiar reaction being: "I exercised; so I can eat a little more".' explains van Kleef. 'Therefore, I was curious as to how exercise commercials can influence food consumption.' To find out, she set up an experiment in which participants were told that they were involved in research into commercials. The test persons were given different commercials to evaluate. One half of them was given neutral commercials, such as on insurances, cars or household equipment. The other half was exposed to commercials which involved exercising. The participants were then asked for their opinions.
The opinion survey was actually a smoke screen to cover up the real research topic: do exercise commercials alter food consumption? As a token of thanks, the test persons were treated to a free buffet lunch afterwards. It was then that the real research began, unknown to the participants. Plates of food stood discretely on weighing scales. Quietly, researchers measured how much food each person took.
There was no denying the results. The group which viewed the exercise commercials consumed almost 25 percent less calories than the group which viewed household commercials. 'This outcome was largely caused by people who were overweight', says van Kleef. According to her, overweight people are more sensitive perhaps because they do not like to exercise, but when confronted with a healthy lifestyle, would decide to eat less to lose weight. The sight of a muscular man or a shapely woman can naturally also stimulate a motivation to lose weight. 'We couldn't establish if the test persons made up for this by eating more later on in the day', she says, putting her results into perspective.
Together with colleagues at the Cornell Food and Brand lab in the United States, van Kleef published her results last month in the International Journal of Behavioural Nutrition and Physical Activity. The article can be found here.