The Study
Very low-calorie diet in candidates for bariatric surgery: change in body composition during rapid weight loss
This study watched what happened to a group of people who ate a very low-calorie diet before surgery. It saw that they lost weight and fat, but it didn't compare them to people who didn't diet—so we can't be sure the diet alone caused the changes. It just shows a pattern, not proof.
Analysis score
Maximum 72 for a cohort study.
Where the score came from
Doctors gave very sick, very heavy patients a super-low-calorie diet for just 8 days before surgery to help them lose weight quickly.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 534 / 100
Quality score
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Losing muscle is bad—it can weaken you.
- 2Even though fat went down fast, the body also broke down muscle, which isn't ideal before major surgery.
- 3They lost 5% of their body weight—85% of that was fat, but 15% was muscle and other lean tissue.
- 4Older and heavier patients lost more of both fat and muscle.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Clinics
Year
2019
Authors
M. P. Serafim, M. Santo, Alexandre Vieira Gadducci, V. M. Scabim, I. Cecconello, R. de Cleva
Related Content
Claims (6)
The total number of calories consumed versus expended determines whether a person gains or loses weight, and the proportions of protein, fat, and carbohydrates in the diet determine how body fat and muscle mass change.
In morbidly obese adults preparing for bariatric surgery, an 8-day very low-calorie diet leads to equal loss of muscle and fat tissue, showing that rapid weight loss does not spare lean tissue.
Among morbidly obese adults who have had bariatric surgery, those with type 2 diabetes lose the same amount of weight, fat, and lean tissue as those without diabetes when following an 8-day very low-calorie diet.
People with BMI over 50 lose more fat and muscle mass than those with BMI between 40 and 50 after an 8-day very low-calorie diet, and the severity of obesity determines how much body composition changes during rapid weight loss.
In morbidly obese adults preparing for bariatric surgery, an 8-day diet of 600 calories per day results in a 5% loss of body weight, with 85% of that loss coming from fat mass, along with measurable decreases in neck, waist, and hip measurements.
Among morbidly obese adults who have had bariatric surgery, those aged 60 and older lose a greater percentage of their body weight and lose more fat mass and muscle mass during an 8-day very low-calorie diet than those under 60.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.