Whether Muscle Mass Before Gastric Bypass Surgery Predicts Weight Loss Afterward
Looks at whether body lean mass before gastric bypass predicts later weight loss.
Plain-language title generated from the registry record
Registry title: Can Pre-operative Lean Mass Predict Weight Loss After Roux-en-Y Gastric Bypass?
Key facts
- Where
- Geneva, SwitzerlandSee the site
Where in Switzerland
- Geneva University HospitalsGeneva, SwitzerlandTaking people
Questions to ask the study team
- How often do I need to come in, and for how long each time?
- Are travel costs paid?
- Can I keep my own doctor?
- What happens if I want to stop?
Trial details
- Who runs it
- University Hospital, Geneva
- Trial code
- NCT07565051
- Record updated
- 8 May 2026
- Original description
The goal of this observational study is to evaluate whether preoperative fat-free mass predicts post-operative weight loss in patients undergoing Roux-En-Y gastric bypass. The primary objective of this study is to evaluate whether preoperative fat-free mass predicts weight loss in the two years following RYGB.Read full original descriptionShow less
Can Pre-operative Lean Mass Predict Weight Loss After Roux-en-Y Gastric Bypass?
The goal of this observational study is to evaluate whether preoperative fat-free mass predicts post-operative weight loss in patients undergoing Roux-En-Y gastric bypass. The primary objective of this study is to evaluate whether preoperative fat-free mass predicts weight loss in the two years following RYGB.
The investigators will collect the following data, assessed as part of routine follow-up:
* height, weight, hip and waist circumferences * body composition by bioimpedance analysis and dual energy-X-ray absorptiometry * Muscle strength and physical activity * Nutritional parameters: resting energy expenditure, eating behavior and digestive tolerance", plasma micronutrient status. . * Cardiovascular risk factors: fasting glucose, blood levels of Hb1Ac, triglycerides, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, blood pressure * Co-morbidities: joint pain and arthritis, sleep apnea, gastro-oesophageal reflux, metabolic dysfunction-associated fatty liver disease (MAFLD), cancer, stroke, heart attack.
Quality of life: quality of life by the "Bariatric Analysis and Reporting Outcome (BAROS) questionnaire", symptoms of dumping syndrome by the "Sigstad diagnostic score system" Birthdate, birthweight and term of their children
Inclusion: Patients ≥ 18 years AND; Meeting inclusion criteria for RYGB (www.smob.ch): BMI ≥35 kg/m2, failure of weight-reducing programs over 2 years (for patients with a BMI ≥50 kg/m2, 1 year), understanding of the necessity to change the lifestyle and eating habits post-operatively, signed consent for lifelong post-operative follow-up in a recognized bariatric center AND; Scheduled RYGB at the HUG OR previous RYGB at the HUG with a present follow-up in Clinical Nutrition and dietetics at the HUG AND; Understanding French.
Exclusion: Planification for another type of bariatric surgery than RYGB; Contra-indications to bariatric surgery as stated under www.smob.ch: insufficient nutritional knowledge in nutrition to lose weight, pregnancy, kidney failure (Creatinine ≥ 300 umol/l without dialysis, Crohn's disease, active cancer or remission < 2 years, active psychiatric disease, substance abuse (alcohol, cannabis, opioids), absence of compliance, lack of understanding of the requirements and necessary lifestyle changes reported by physician or dietician; Inability or refusal to give consent.