Thinking people are born fat or born thin is bad for your health

"If an individual believes weight to be outside of the influence of diet and exercise, she or he may engage in more behaviors that are rewarding in the short term, such as eating unhealthful foods and avoiding exercise, rather than healthful behaviors with more long-term benefits for weight management," wrote study authors Dr. Mike C. Parent and Dr. Jessica L. Alquist. "By fighting the perception that weight is unchangeable, health care providers may be able to increase healthful behaviors among their patients."

Analyzing data from both medical and self-reported health measurements of 4,166 men and 4,655 women, the study authors found the following:

• As people get older, the belief that weight is unchangeable and determined by DNA is associated with less healthy eating behavior. For example, as people age, they are less likely to examine food nutrition labels and to make fruits and vegetables available at home.
• As people get older, the belief that weight is unchangeable is associated with less exercise.
• As people get older, the belief that weight is unchangeable is associated with eating more frozen meals (e.g., pizza), restaurant meals and 'ready-to-eat foods' (e.g., deli foods).

"Although previous research has found gender differences in weight as a motivation for exercise and healthful eating, we did not find evidence that gender affected the relationship between health beliefs and physical activity or healthful eating," wrote the study authors. "However, we found evidence that the relationship between belief in weight changeability and exercise, healthful eating, and unhealthful eating differs by age."