Muddled thinking is fuelling obesity epidemic

People's beliefs about the causes of obesity can affect their own weight, my research has shown.

If you think lack of exercise is the primary cause of obesity, you are more likely to be overweight than someone who implicates poor diet.

A 2010 survey revealed that 39.2 per cent of adults in Hong Kong are overweight, and this proportion is steadily growing. Google searches for "Hong Kong" and "weight loss" turn up over 8.25 million hits. Clearly this issue matters to a lot of people.

Weight loss is one of the most common goals people have. However, when looking for ways to lose weight, people encounter advice that is often outright contradictory - some "experts" encourage greater exercise, some advocate reduced calorie intake, and others lay the blame on genetics.

As a result, there are differing beliefs about the best way to lose weight (ie. what specific steps one should take).

New research shows that these beliefs have real consequences - they predict an individual's actual body mass. In a series of studies forthcoming in the journal Psychological Science, Brent McFerran of the University of Michigan and I examined what regular people believe causes obesity. We asked over 1,200 people from five countries on three continents about their beliefs regarding the primary cause of obesity, and found a roughly equal split between people primarily blaming overconsumption of calories and those blaming a lack of exercise. More interestingly, those who blamed a lack of exercise were more likely to be overweight, and indeed ate more food.

Why is this? People's beliefs guide their actions. If we believe overeating causes obesity, and we want to lose weight, we cut our intake. If, on the other hand, we believe weight gain stems from insufficient exercise, we try to increase our activity.