Frequently, discussions about persons with obesity will include a view that persons with obesity have a personality defect which impedes their ability to limit food intake or sustain a regimen of physical activity. Rather than ignore such views, it might be helpful to see how research on personality and obesity provides us with enhanced understanding. A series of papers by Dr. Angela Sutin and colleagues provides helpful insights. A 2011 paper found that the most disciplined consumers had lower rates of obesity while large weight gains were found among consumers scoring high on measures of impulsiveness, low conscientiousness and willingness to take risks. (These are standard categories for assessing personality types.) (Sutin AR, Ferrucci L, Zonderman AB, Terracciano A. Personality and obesity across the adult life span J Pers Soc Psychol 2011 Sep;101(3):579-92) Going further, a 2013 paper by Sutin and colleagues found that persons who rated high on impulsiveness and lacked discipline or low conscientiousness had high circulating levels of leptin, which plays a critical role in weight regulation, even after controlling for body mass index, waist circumference or inflammatory markers. (Sutin AR, Zonderman AB, Uda M, Deiana B et al Personality Traits and Leptin Psychosom Med. 2013 Jun;75(5):505-9)
A third paper by Sutin and colleagues, “I Know Not to but I Can’t Help It: Weight Gain and Changes in Impulsivity Related Personality Traits,” asked whether weight gain or loss of 10% or more led to personality changes, specifically impulsiveness and deliberation. The researchers found that compared to participants who remained weight stable, those who gained weight became more impulsive. Those who did not gain weight showed a predicted loss in impulsiveness. But contrary to their hypothesis, weight gain was also associated with increases in deliberation. In other words, subjects who were gaining weight became more thoughtful before acting. The authors opined that as participants gained weight they bought into the American stereotypes about persons with obesity. So they saw themselves as more impulsive even as they were increasing in deliberativeness. There had no change in self-discipline.
A recent paper has found that only conscientiousness showed a robust association with both BMI and obesity risk. Conscientiousness was associated with obesity risk among Hispanics and is larger for women than men. (Kim, J. Personality traits and body weight: Evidence using sibling comparisons. Soc Sci Med 2016 Jul 1:163:54-62)