OBJECTIVE: To evaluate the short-term effects of sibutramine on appetite and eating behaviour and whether these effects are related to the long-term therapeutic outcome.

STUDY DESIGN: Short-term: randomised, double-blind, placebo-controlled, within-subject design. Long-term: prospective open clinical trial.

SUBJECTS: A total of 36 obese (nine men/27women) with a body mass index of 39.3±4.3 (mean±sd)(range 30.2?–? 45.2)? kg/m 2 and age 44.4±12.1? y.

PROCEDURE AND METHODS: First phase—short-term effects: At baseline, the subjects were treated for 14 days with 15? mg sibutramine/placebo (period 1) followed by a 2 weeks single-blind placebo washout period, the subjects received the alternative therapy for another 14 days (period 2). At baseline, and at day 14 in each treatment period the subjects arrived fasting to the laboratory for a standardised breakfast and an ad libitum standardised lunch using the VIKTOR set-up (a universal eating monitor) to evaluate the microstructure of the eating behaviour (ie amount of food consumed and eating rate). Visual Analogue Scales were applied before and after the meals as well as every hour between the meals to monitor the appetite. During this first phase, subjects were encouraged to keep their habitual eating habits. Second phase—long-term effects: All subjects received 10 months open treatment with 15? mg sibutramine and dietary advice in monthly group sessions with a dietitian. On the last day of this treatment period, the subjects returned to repeat the measurements of appetite and eating behaviour using the same test procedure as during the first phase of the study.

RESULTS: First phase: Sibutramine influenced appetite and eating behaviour that could be registered after only 14 days of treatment. The amount of food consumed at lunch on VIKTOR was reduced by 16% by sibutramine compared to placebo, 335±123? g vs 399±126? g (P< 0.0001). Second phase: Responders and nonresponders were defined as those who ate less vs more food on VIKTOR when treated with sibutramine compared to the baseline food intake in the first phase of the study. The weight reduction was greater for responders 11.8±6.2 (mean±sd)? kg compared to nonresponders 6.8±2.7 (mean±sd)? kg (P< 0.05).

CONCLUSION: Short-term effects of sibutramine on appetite and eating behaviour were identified such as a reduction in food intake and in ratings of subjective motivation to eat. Short-term sibutramine effects on eating behaviour are to some extent related to the long-term therapeutic outcome in obese subjects.