We all know, generally speaking, that body weight is a function of the number of calories ingested minus the number of calories burned, right? If you eat more than you burn off, you gain weight. If you eat less than you burn off, you lose. Likewise, if you burn off more calories than you eat, you lose weight, too. Simple science. Basic biochemistry.
But the psychology of weight loss is not so clear cut. It turns out that how you approach this basic equation really matters to your success in maintaining the weight you want. Those who believe what you eat is the primary factor of weight gain are more likely to be slim than those who believe that more activity is the right solution—even though they're both right.
Why is that? Brent McFadden, a professor at the University of Michigan at Ann Arbor, explained this finding in a piece he wrote for Psychology Today. People tend to underestimate the number of calories they consume and overestimate the number they burn through exercise. When someone thinks that diet is the cause, they tend to watch what they eat more carefully. This causes them to eat fewer calories than those who take the exercise-first approach.
McFadden and the other researchers conducted six studies that explored people’s beliefs about the cause of obesity to compare the results. The investigators worked with research facilities in Korea, France, Canada, Hong Kong and the United States for the studies.
They found that people who associated diet as the primary cause of weight gain actually weighed less than the participants who thought lack of exercise caused obesity. They also found that exposing people to the message that diet led to weight gain caused them to eat less than a similar message that lack of exercise caused weight gain. (Interestingly, this might have negative implications for Michelle Obama's Get Moving program.)
The takeaway here is that although weight is still tied to diet and activity level, diet is the stronger factor psychologically because we tend to underestimate the amount we eat. On the other hand, we're here to tell you that exercise is still important. It helps you burn calories and build muscle, both of which help maintain a healthy weight. But it really helps to keep track of what you're eating, too.