Introduction: The aim of this treatment study was to evaluate both short- and long-term effects of a multidisciplinary obesity treatment. Long-term outcomes of patients receiving gastric bypass surgery in addition to behavioral obesity treatment were compared with those who did not undergo surgery.

Material and methods: The participants were 100 patients undergoing a four week inpatient obesity treatment at the Hospital in Neskaupsstaður (Fjórðungsjúkrahúsið í Neskaupstað (FSN). After treatment was completed, 28 of these patients underwent further treatment, receiving gastric bypass surgery. All patients were followed for two years after completing the four week treatment. Body mass index (BMI), quality of life and symptoms of depression and anxiety were measured for all participants before and after treatment, and again using mailed questionnaires in a cross-sectional data collection in the summer of 2012.

Results: Participants achieved statistically significant weight loss (median 1,85 BMI points), improved their quality of life and mental health after four week obesity treatment, and long term results remained significant. Three years after the conclusion of treatment, statistically significant weight loss was still present for patients that had not undergone gastric bypass surgery (median 2.13 BMI points), but improvements in mental health and quality of life were no longer present among subjects who did not undergo surgery. Patients who underwent gastric bypass surgery achieved greater weight loss (median 13.12 BMI points) and longer lasting improvements in mental health and quality of life.

Conclusion: Results show that the multidisciplinary obesity treatment is effective in reducing obesity and improving mental health and quality of life in the short term. With follow-up treatment, the weight loss is maintained for up to three years after treatment for all participants. The bypass surgery group lost more weight and showed more permanent improvements in mental health and quality of life. These results underline the necessity of providing long-term treatment in maintaining improvements when treating obesity.