Obesity, Weight-Loss Failure Linked to Personality Traits

Individuals with eating disorders possess certain personality traits, some studies have suggested. For example, individuals with anorexia nervosa were found to score high on persistence, whereas binge eaters were found to score high on novelty seeking.

And now a new study, reported in the April International Journal of Obesity, has not only strongly linked novelty seeking with obesity, but with difficulty in losing weight.

The study was conducted by C. Robert Cloninger, M.D., a professor of psychiatry and genetics at Washington University in St. Louis, and colleagues. Cloninger was one of the developers of the Temperament and Character Inventory (TCI), which measures seven dimensions of personality—novelty seeking, harm avoidance, reward dependence, persistence, self-directedness, cooperativeness, and self-transcendence. Cloninger and his colleagues also used the TCI as their yardstick in this study.

The TCI was used to assess the personalities of 264 lean and 56 obese people living in the St. Louis area, as well as 183 obese individuals enrolled in the Washington University Weight Management Program, which involved weekly group-behavioral therapy and diet-education sessions for 22 weeks.

The researchers compared the personalities of the obese subjects in the community with those of the lean subjects, the obese subjects enrolled in the weight-management program with obese people in the community, and the weight-managementprogram enrollees who managed to lose more than 10 percent of their weight with those who did not.

The comparisons revealed some statistically significant differences in personality characteristics between the groups. Specifically, when obese subjects in the community were compared with lean subjects there, the former scored significantly higher in novelty seeking, significantly lower in persistence, and significantly lower in self-directedness. Obese subjects enrolled in the weight-management program scored significantly higher than did obese subjects in the community on both reward dependence and cooperativeness. And subjects in the weight-management program who managed to lose more than 10 percent of their weight scored significantly lower on novelty seeking than did those in the program who failed to lose that much weight.

In sum, “these data suggest that specific personality characteristics are involved in the pathogenesis of obesity,” Cloninger and his group concluded.

In their report, they also discussed some of the practical implications of their findings.

For example, because novelty seeking was strongly associated with obesity in the general population and with obese individuals' difficulty in losing weight, “high novelty-seeking scores indicate a strong appetite drive,” they noted.

People who are self-directed are able to set and pursue meaningful goals. Because obese subjects scored lower on self-directedness than lean subjects did, their difficulty in losing weight may partially stem from their difficulty in setting and pursuing goals.

Reward-dependent individuals, according to the TCI, tend to be emotionally warm and sociable and to need social approval. Obese individuals enrolled in the weight-loss program tended to fall into this group. So the reason why they enrolled in the program may be because they had no aversion to being part of a group and because they were eager to lose weight and reap social approval for it.

The study results might also be used to help obese people lose weight, Cloninger and his team speculated. For example, personality characteristics might be used to identify patients in advance who can benefit from behavioral weight-loss therapy. Or weight-loss programs might be designed to take into consideration the personality traits of their clients.

“This study adds to growing evidence that neuropsychological factors play an important role in causing obesity, which is one of the largest public health problems facing our society,” James Hudson, M.D., Sc.D., a professor of psychiatry at Harvard University and an eating-disorders expert, told Psychiatric News. In 2005, in fact, Hudson predicted that“ neuropsychological factors are going to emerge as one of the important causes of obesity” (Psychiatric News, September 16, 2005).

The investigation is “indeed very interesting,” Michael Devlin, clinical co-director of eating disorders research at the New York State Psychiatric Institute, commented. “Regarding the comparison between obese and normal-weight individuals, I think it demonstrates pretty convincingly that there are aspects of temperament and character that may be associated with obesity. This is not to say that there is an `obese personality type.' Rather, it may be that some particularly high or low scores on certain dimensions of temperament or character—and the corresponding neurobiological patterns—may, in combination with other genetic and environmental factors, contribute to an individual's predisposition to obesity or to the full expression of her or his potential for obesity.”

The study was funded by the National Institutes of Health.

An abstract of “Personality Characteristics in Obesity and Relationship With Successful Weight Loss” is posted at<www.nature.com/ijo/journal/v31/n4/abs/0803464a.html>.▪