What you believe causes obesity can affect your actual weight and may be predictive of whether you become overweight.
An international study consisting of surveys conducted in five countries by researchers from the University of Michigan and the Hong Kong University of Science and Technology found that people tend to believe either poor diet or lack of exercise is the leading cause of weight gain. Survey respondents who assumed diet was the primary cause had lower BMIs than those who thought lack of exercise was the key factor. The researchers suggested this may be because people who thought exercise deficiency was critical tended to eat more food than those who attributed obesity to poor diet.
Researchers surveyed people in Canada, Korea, France, Hong Kong and the United States about what they believed were the reasons for obesity; they also collected data on gender, height and weight, and, in some circumstances, provided chocolates for snacking.
Lead study author Brent McFerran, PhD, professor at the Ross School of Business at the University of Michigan in Ann Arbor, told IDEA Fitness Journal, “We know from a whole host of research that our beliefs guide our actions. Most people wish to avoid weight gain. How would they accomplish weight loss or weight maintenance? If I believe that diet is the cause, I will watch what I eat, and worry less about exercise. On the other hand, if I indict a lack of exercise, I am going to increase the amount I exercise.
“But we know from medical research that the former should be more effective, meaning these people should actually be thinner. This happens for a couple of reasons. First, people often reward themselves with additional calories following rigorous exercise. Second, people grossly underestimate how many calories are in what they eat, and they overestimate how many calories they burn while exercising. Exercise is effective in weight loss, but only if calorie consumption does not increase alongside it. Unfortunately, it often does.”
McFerran emphasized that fitness pros should be clear with clients about the importance of nutrition. “Our research shows that about half of people are quite misinformed about how best to lose or maintain their weight. It's especially problematic when people in positions of authority, such as trainers, suggest to their clients that they can simply increase the amount they exercise without changing their diet as a path to weight loss. Ensuring that exercise programs are coupled with a healthy diet should be paramount.”
The study was published in the journal of the Association for Psychological Science, Psychological Science (2013; doi: 10.1177/0956797612473121), and is available online at http://pss.sagepub.com/content/early/2013/06/05/0956797612473121.