Energy, Attentiveness, and Fatigue After Bariatric Surgery and Associations with Daily Physical Activity and Weight Loss: an Ecological Momentary Assessment Study.

PURPOSE Energy and fatigue are thought to improve after bariatric surgery. Such improvements could be related to weight loss and/or increased engagement in day-to-day health behaviors, such as moderate-to-vigorous physical activity (MVPA). This study used ecological momentary assessment (EMA) to evaluate several aspects of energy/fatigue in real-time in patients' natural environment during the first year after surgery and assessed the associations of percent total weight loss (%TWL) and daily MVPA with daily energy/fatigue levels. METHODS Patients (n = 71) undergoing Roux-en-Y gastric bypass or sleeve gastrectomy rated their energy, alertness and attentiveness (averaged to create an "attentiveness" rating), and tiredness and sleepiness (averaged to create a "fatigue" rating) via smartphone-based EMA at 4 semi-random times daily for 10 days at pre-surgery and 3-, 6-, and 12 months post-surgery. Daily MVPA minutes were assessed via accelerometry. Weight was measured in clinic. RESULTS Energy ratings initially increased from pre- to post-surgery, before leveling off/decreasing by 12 months (p < 0.001). Attentiveness and fatigue ratings did not change over time. %TWL was unrelated to any ratings, while MVPA related to both energy and attentiveness but not fatigue. Participants reported more energy on days with more total MVPA min (p = 0.03) and greater attentiveness on days with more total (p < 0.001) and bouted (p = 0.02) MVPA. CONCLUSIONS While more research is needed to confirm causality, results suggest that greater daily MVPA is associated with increased daily energy and attentiveness among bariatric surgery patients, independent of %TWL. Findings add to growing evidence of MVPA's potential benefits beyond energy expenditure in the context of bariatric surgery.