Environmental food cues may be trigger.

• Position: Obesity

People who are obese may be more susceptible to environmental food cues than their lean counterparts due to differences in brain chemistry that make eating more habitual and less rewarding, according to a study published in Molecular Psychiatry.

Researchers found that, when examining men and women with varying amounts of body fat, obese participants tend to have greater dopamine activity in the habit-forming region of the brain than lean counterparts, and less activity in the region controlling reward. Those differences potentially could make the obese people more drawn to overeat in response to food triggers while simultaneously making food less rewarding to them. A chemical messenger in the brain, dopamine influences reward, motivation, and habit formation.

"While we cannot say whether obesity is a cause or an effect of these patterns of dopamine activity, eating based on unconscious habits rather than conscious choices could make it harder to achieve and maintain a healthy weight, especially when appetizing food cues are practically everywhere," says Kevin D. Hall, lead author and a senior investigator at the National Institute of Diabetes and Digestive and Kidney Diseases. 'This means that triggers such as the smell of popcorn at a movie theater or a commercial for a favorite food may...