Researchers were curious whether or not labelling exercise "fat-burning" (as many exercise machines do) would have an impact on how much food a person ate post exercising.
The protocol was simple. Subjects were brought individually to a lab and were told they were there to evaluate newly developed training software for bike ergometers. They were then equipped with a heart rate monitor and completed a 20 minute low-moderate intensity cycle. Participants were randomly assigned to have one of two posters tacked to the wall in front of them while they rode. The first had a poster stating, "Fat-burning exercise – developing training software for exercise in the fat-burning zone.", and the second, "Endurance exercise – developing training software for exercise in the endurance zone." Following their rides subjects were told they could help themselves to snacks while completing a survey and were offered water and pretzels. Pretzels consumed were measured by means of a scale before and after each participant.
"Fat-burning" labels did have some impact, but I'm not going to dwell on it. Instead I want to point out that across both treatments participants burned on average 96 calories during their rides and they then proceeded to eat 135 calories (41% more calories than they burned) of post-exercise pretzels.
Combine these results with those from a study published a few weeks ago that people who went for a walk and told they were "exercising" consumed 41% more calories from indulgent desserts and drinks following a post-walk lunch than those who were told they were walking for "fun".
We do eat because we exercise and I think in large part it's because we've been taught that we're supposed to - both by the food industry (see up above) and sadly too, by public health departments (see down below with the "Less Sit, More Whip" City of Ottawa bus poster) and health professionals who have markedly overplayed exercise's role in weight management.
Lose weight in the kitchen, gain health in the gym.