Personality plays role in body weight: Impulsivity strongest predictor of obesity

Impulsivity was the strongest predictor of who would be overweight, the researchers found. Study participants who scored in the top 10 percent on impulsivity weighed an average of 22 lbs. more than those in the bottom 10 percent, according to the study.

"Individuals with this constellation of traits tend to give in to temptation and lack the discipline to stay on track amid difficulties or frustration," the researchers wrote. "To maintain a healthy weight, it is typically necessary to have a healthy diet and a sustained program of physical activity, both of which require commitment and restraint. Such control may be difficult for highly impulsive individuals."

The researchers, from the National Institute on Aging, looked at data from a longitudinal study of 1,988 people to determine how personality traits are associated with weight and body mass index. Their conclusions were published online in the APA's Journal of Personality and Social Psychology.

"To the best of our knowledge, we are the first to examine whether personality is associated with fluctuations in weight over time," they wrote. "Interestingly, our pattern of associations fits nicely with the characteristics of these traits."

Participants were drawn from the Baltimore Longitudinal Study of Aging, an ongoing multidisciplinary study of normal aging administered by the National Institute on Aging. Subjects were generally healthy and highly educated, with an average of 16.53 years of education. The sample was 71 percent white, 22 percent black, 7 percent other ethnicity; 50 percent were women. All were assessed on what's known as the "Big Five" personality traits -- openness, conscientiousness, extraversion, agreeableness and neuroticism -- as well as on 30 subcategories of these personality traits. Subjects were weighed and measured over time. This resulted in a total of 14,531 assessments across the 50 years of the study.

Although weight tends to increase gradually as people age, the researchers, led by Angelina R. Sutin, PhD, found greater weight gain among impulsive people; those who enjoy taking risks; and those who are antagonistic -- especially those who are cynical, competitive and aggressive.

"Previous research has found that impulsive individuals are prone to binge eating and alcohol consumption," Sutin said. "These behavioral patterns may contribute to weight gain over time."

Among their other findings: Conscientious participants tended to be leaner and weight did not contribute to changes in personality across adulthood.

"The pathway from personality traits to weight gain is complex and probably includes physiological mechanisms, in addition to behavioral ones," Sutin said. "We hope that by more clearly identifying the association between personality and obesity, more tailored treatments will be developed. For example, lifestyle and exercise interventions that are done in a group setting may be more effective for extroverts than for introverts."