A comparative controlled study of personality in severe obesity: a 2-y follow-up after intervention

The primary purpose was to examine 2-y effects of weight change on personality traits in severely obese subjects treated conventionally or surgically. We also assessed differences between the severely obese patients and a primarily normal-weight reference group.

Personality traits were assessed using 7 of 15 scales from the Karolinska Scales of Personality (KSP): Somatic Anxiety, Muscular Tension, Psychasthenia, Psychic Anxiety, Monotony Avoidance, Impulsiveness, and Irritability. A total of 1380 surgical candidates, 1241 conventionally treated patients and 1135 subjects from the SOS (Swedish Obese Subjects) reference study, representing the general population, completed the KSP. Data presented in this study were gathered twice from the patients (prior to treatment and after 2 y) and once from the reference subjects. Significance tests and effect sizes (ES) were calculated.

At baseline, the obese were characterised as more anxiety prone, impulsive, irritable and less monotony avoiding than the reference group; surgery patients more so than the conventionally treated. At follow-up, it was found that anxiety proneness decreased and Monotony Avoidance increased with increasing weight loss. The conventionally treated were, on average, weight stable and, hence, only a small decrease was noted regarding Somatic Anxiety. The surgery group lost on average 28 kg, and differences between surgically treated and the reference group decreased on all scales except Impulsiveness, which remained unchanged. The largest improvement was in relation to Psychasthenia.

Weight reduction maintained for 2 y was associated with changes on practically all personality traits in proportion to the magnitude of weight loss. In particular, Psychasthenia seemed to be alleviated, while Impulsiveness was unaffected.