The researchers, writing in the American Journal of Clinical Nutrition, found that those who had successfully maintained weight loss responded differently to pictures of high calorie foods, with heightened brain activity observed in areas associated with behavioral control and visual attention. An accompanying editorial suggests that this could help develop cognitive behavioral therapy techniques to alter attitudes toward food.
Lead author Jeanne McCaffery of the Miriam Hospital’s Weight Control and Diabetes Research Center said: “Our findings shed some light on the biological factors that may contribute to weight loss maintenance. They also provide an intriguing complement to previous behavioral studies that suggest people who have maintained a long-term weight loss monitor their food intake closely and exhibit restraint in their food choices.”
Maintaining weight loss in the long term is a major problem in treating obesity, the authors claim. They say that those involved in behavioral weight loss programs lose an average of eight to ten percent of their weight during the first six months and maintain about two-thirds of it after a year. However, after five years most patients tend to have returned to their original weight.
Participants of the study were split into three groups: 16 obese individuals; 17 who had maintained a weight loss of 30lb or more for at least three years; and 18 individuals of normal weight.
They were shown images of low-calorie foods such as whole grain cereals, fruits and vegetables; high-calorie foods such as cheeseburgers, French fries, hot dogs and cakes; and non-food items such as shrubs, bricks and flowers. The researchers measured their brain response using functional magnetic resource imaging (fMRI).
They found that for those who had maintained weight loss brain activity, when shown pictures of high-calorie foods, was different from the other two groups.
McCaffrey said: “It is possible that these brain responses may lead to preventative or corrective behaviors – particularly greater regulation of eating – that promote long-term weight control. However, future research is needed to determine whether these responses are inherent within an individual or if they can be changed.”
Obesity has become a major public health crisis in the US, where the rate of obesity has climbed from 15 percent of the population in 1980 to 34 percent today.
More than two-thirds of the population is now overweight or obese, which raises the likelihood of a host of diseases, including hypertension, diabetes and stroke.
Source: American Journal of Clinical Nutrition
“Differential functional magnetic resonance imaging response to food pictures in successful weight-loss maintainers relative to normal-weight and obese controls”
Authors: Jeanne M McCaffery, Andreana P Haley, Lawrence H Sweet, Suzanne Phelan, Hollie A Raynor, Angelo Del Parigi, Ron Cohen, and Rena R Wing