Vertical sleeve gastrectomy in adolescents reduces the appetitive reward value of a sweet and fatty reinforcer in a progressive ratio task

BACKGROUND: Adolescent obesity is challenging to treat even if good multidisciplinary approaches are started early. Vertical sleeve gastrectomy (VSG) is an effective intervention for long-term weight loss, but the underlying mechanisms that result in reduced calorie intake are controversial. Anecdotal evidence from the clinic and evidence in rodents after VSG suggest a decrease in the reward value of high-calorie dense foods. OBJECTIVES: To determine changes in appetitive behavior of candies (high in sugar and fat) after VSG in adolescents with obesity. SETTING: University hospital. METHODS: Sixteen adolescents with obesity (age 15.3 ± .5 yr) who had VSG and 10 control patients (age 13.8 ± .6 yr) who had not undergone surgery were studied. Both groups completed a progressive ratio task by clicking a computer mouse on a progressive ratio schedule to receive a candy high in sugar and fat. In the task, patients were required to expend an increasing amount of effort to obtain the reinforcer until they reach a breakpoint (measure of the reward value of the reinforcer). The task was performed before VSG and 12 and 52 weeks after VSG. RESULTS: The VSG group's bodyweight decreased from the baseline 136.6 ± 5.1 to 110.9 ± 5.2 to 87.4 ± 3.7 kg after 12 and 52 weeks, respectively (P < .001). The median breakpoint for candies decreased after VSG from the baseline 320 (160-640) to 80 (50-320) to 160 (80-560) after 12 and 52 weeks, respectively (P = .01). Breakpoints for the control patients did not change (480 [160-640] versus 640 [280-640], P = .17). CONCLUSION: VSG resulted in a reduction in the reward value of a candy, as suggested by the reduced amount of effort adolescents were prepared to expend to obtain the high-sugar and high-fat candy. The effect was most pronounced 12 weeks after surgery but was largely maintained at 1 year. Long-term attenuation of appetitive behavior may be the key to weight loss and weight loss maintenance after VSG in adolescents.