Background: Roux-en-Y gastric bypass (RYGB) surgery is usually followed by great weight loss and improved health related quality of life (HRQoL). However, weight regains are seen in some patients approximately 1-2 years post-surgery, associated with a decrease in HRQoL and physical activity (PA).

Objectives: To investigate if a dissonance-based group intervention post RYGB surgery has an effect on women’s HRQoL, PA and other health-related behaviors: a protocol paper.

Methods: The ongoing RCT is a dissonance-based intervention for female RYGB patients from five Swedish hospitals. Participants are randomized to either control (usual follow-up care) or intervention group (4 sessions, 3 months post-surgery). Main topics of intervention sessions are (1) PA, (2) eating behavior, (3) social and (4) intimate relationships. Participants are asked to wear an accelerometer and complete questionnaires measuring HRQoL (SF-36), social adjustment, eating behavior and body esteem, pre-surgery and 6, 12 and 24 months post-surgery. Planned analysis includes intention to treat and per protocol analysis on differences between intervention and control group. Trial registration number: ISRCTN16417174.

Results: We recruited 259 women (156 intervention and 103 controls). Mean BMI was 40.9 ± 4.7, mean SF36 score was 42.1 ± 9.5 (physical component summary score) and 45.8 ± 11.1 (mental component summary score). Mean time spent in moderate to vigorous PA was 28.8 ± 19.4 min/day and sedentary was 458.3 ± 100.4 min/day.

Conclusions: This trial aims to improve outcomes after RYGB. If the intervention is effective, implementation within the Swedish health care system is possible within the near future.