Evaluation of the impact of gastric bypass surgery on eating behaviour using objective methodologies under residential conditions: Rationale and study protocol.

Gastric bypass surgery leads to significant and sustained weight loss and a reduction in associated health risks in individuals with severe obesity. While reduced energy intake (EI) is the primary driver of weight loss following surgery, the underlying mechanisms accounting for this energy deficit are not well understood. The evidence base has been constrained by a lack of fit-for-purpose methodology in assessing food intake coupled with follow-up studies that are relatively short-term. This paper describes the underlying rationale and protocol for an observational, fully residential study using covert, objective methodology to evaluate changes in 24-hr food intake in patients (n = 31) at 1-month pre-surgery and 3-, 12- and 24-months post-surgery, compared to weight-stable controls (n = 32). The main study endpoints included change in EI, macronutrient intake, food preferences, and eating behaviours (speed, frequency, and duration of eating). Other physiological changes that may influence EI and weight regulation including changes in body composition, circulating appetite hormones, resting metabolic rate, total energy expenditure and gastrointestinal symptoms were also evaluated. Understanding which mechanisms contribute to a reduction in EI and weight loss post-surgery could potentially help to identify those individuals who are most likely to benefit from gastric bypass surgery as well as those that may need more targeted intervention to optimise their weight loss post-surgery. Furthermore, clarification of these mechanisms may also inform targeted approaches for non-surgical treatments of obesity.

Early Post-operative Weight Change After Roux-en-Y Gastric Bypass Predicts Weight Loss at 12-Month Follow-up.

INTRODUCTION: Sub-optimal weight loss following Roux-en-Y gastric bypass (RYGB) represents an important clinical challenge in a significant number of patients. Early identification of such patients would be advantageous, as it could aid in the selective implementation of targeted adjunct interventions during the first post-operative year. METHODS: Clinical audit data from 1137 patients undergoing RYGB between 2013 and 2016 at the Instituto Sallet in Brazil were prospectively registered in an online database (BOLD) and analyzed. RESULTS: Forty-eight percent of patients achieving less than 5% total weight loss after the first post-operative month achieved a 20% total weight loss at 1 year (n = 626; OR = 0.6 CI = 95%). Eighty-three percent of patients losing between 5 and 10% at 1 month and 95% of patients losing greater than 10% at 1 month had lost at least 20% of total body weight after the first post-operative year. Forty-four percent of patients achieving less than 10% total weight loss after the third post-operative month achieved 20% total weight loss at 1 year (n = 494; OR = 0.3 CI = 95%). CONCLUSION: Total bodyweight reduction after RYGB of < 5% at 1 month and < 10% at 3 months is associated with suboptimal weight loss at 1 year. These results reinforce findings from other studies reporting that patients tend to follow a common weight loss trajectory. Identifying the patients with weight trajectory requiring adjunct therapies early on is crucial so appropriate adjustments can be made to post-operative care.

Effect of Gastric Bypass vs Best Medical Treatment on Early-Stage Chronic Kidney Disease in Patients With Type 2 Diabetes and Obesity: A Randomized Clinical Trial.

Importance: Early-stage chronic kidney disease (CKD) characterized by microalbuminuria is associated with future cardiovascular events, progression toward end-stage renal disease, and early mortality in patients with type 2 diabetes. Objective: To compare the albuminuria-lowering effects of Roux-en-Y gastric bypass (RYGB) surgery vs best medical treatment in patients with early-stage CKD, type 2 diabetes, and obesity. Design, Setting, and Participants: For this randomized clinical trial, patients with established type 2 diabetes and microalbuminuria were recruited from a single center from April 1, 2013, through March 31, 2016, with a 5-year follow-up, including prespecified intermediate analysis at 24-month follow-up. Intervention: A total of 100 patients with type 2 diabetes, obesity (body mass indexes of 30 to 35 [calculated as weight in kilograms divided by height in meters squared]), and stage G1 to G3 and A2 to A3 CKD (urinary albumin-creatinine ratio [uACR] >30 mg/g and estimated glomerular filtration rate >30 mL/min) were randomized 1:1 to receive best medical treatment (n = 49) or RYGB (n = 51). Main Outcomes and Measures: The primary outcome was remission of albuminuria (uACR <30 mg/g). Secondary outcomes were CKD remission rate, absolute change in uACR, metabolic control, other microvascular complications, quality of life, and safety. Results: A total of 100 patients (mean [SD] age, 51.4 [7.6] years; 55 [55%] male) were randomized: 51 to RYGB and 49 to best medical care. Remission of albuminuria occurred in 55% of patients (95% CI, 39%-70%) after best medical treatment and 82% of patients (95% CI, 72%-93%) after RYGB (P = .006), resulting in CKD remission rates of 48% (95% CI, 32%-64%) after best medical treatment and 82% (95% CI, 72%-92%) after RYGB (P = .002). The geometric mean uACRs were 55% lower after RYGB (10.7 mg/g of creatinine) than after best medical treatment (23.6 mg/g of creatinine) (P < .001). No difference in the rate of serious adverse events was observed. Conclusions and Relevance: After 24 months, RYGB was more effective than best medical treatment for achieving remission of albuminuria and stage G1 to G3 and A2 to A3 CKD in patients with type 2 diabetes and obesity. Trial Registration: ClinicalTrials.gov Identifier: NCT01821508.