Aim: To study the associations between weight loss with sibutramine and orlistat with psychological aspects that may interact with patients' response to these drugs.
Methods: A total of 478 obese patients with a mean body mass index of 42 +/- 12 kg/m(2) gave self-reported, retrospective data on different types of previous weight loss treatments (sibutramine and orlistat, and Weight Watchers used as a control condition) including the amount of weight lost with these treatments, eating behaviour (Dutch Eating Behaviour Questionnaire) and personality (NEO Personality Inventory - Revised).
Results: Greater weight loss with sibutramine was associated with lower levels of restrained eating and higher levels of 'neuroticism', in particular 'anxiety' and 'depression'. Greater weight loss with orlistat was associated with aspects of the personality dimension 'conscientiousness' (e.g. 'order' and 'deliberation').
Conclusion: Sibutramine may exert its greatest effect in patients whose eating is a 'natural' response to hunger rather than regulated by cognitions and conscious controls. Patients with low levels of restraint could be more sensitive to the satiety-enhancing effect of sibutramine. They may be able to reduce their food intake without cognitive interference and/or start to control their eating most radically in response to enhanced satiety. Enhanced satiety may also help patients withstand a wish to eat triggered by psychological distress. Possible central nervous system effects on mood could also have reduced eating, which was related to distress. The administration regimen of orlistat is more demanding, requiring greater adherence. This can account for the finding that personality attributes such as conscientiousness are important for success.