Last updated July 14, 2026
Key finding
Total weight loss was -17.6 ± 6.0 kg for RYGB vs. -15.6 ± 5.1 kg for VLCD (p = 0.335).
This study compared the effectiveness of Roux-en-Y gastric bypass (RYGB) and a very low-calorie diet (VLCD) in individuals with obesity, finding no significant differences in weight loss outcomes.
Quick read
The essential study design details in one scan.
EvidenceScore™
Moderate
Study type
RCTs
Follow-up
Medium-Term (3–12 mo)
Risk of bias
Some Concerns
Save research, organize studies, and quickly find important evidence again.
Plain-language summary
A plain-language read of the study’s main message and where it applies.
Study focus
This study compared the effectiveness of Roux-en-Y gastric bypass (RYGB) and a very low-calorie diet (VLCD) in individuals with obesity, finding no significant differences in weight loss outcomes.
Understanding the comparative effectiveness of RYGB and VLCD is crucial for clinicians and patients when considering treatment options for obesity. The findings suggest that both interventions can lead to significant weight loss and health improvements, allowing for informed decision-making based on patient preferences and individual circumstances.
The study design was non-randomized, which may introduce bias. Sample size and demographic characteristics were not specified. Results may not be generalizable to all populations with obesity.
Published in
Publication details and source links for this paper.
Chanawit S, Prapimporn CS, Supphamat C, et al. A Very Low-Calorie Diet Compared with Roux-en-Y Gastric Bypass Surgery in Individuals with Obesity. Nutrients. 2024;16(15):2407. doi:10.3390/nu16152407
Total weight loss was -17.6 ± 6.0 kg for RYGB vs. -15.6 ± 5.1 kg for VLCD (p = 0.335).
Percentage weight loss was -16.2% ± 4.3% for RYGB vs. -14.1% ± 3.6% for VLCD (p = 0.147).
Changes in body composition and resolution of comorbidities were similar between groups at 12 weeks.
Evidence network
Understand where this research contributes within the broader evidence network.
This study contributes evidence to Gastric bypass, Very-low-calorie ketogenic diet and Change in body composition after 12 weeks of treatment, Percentage weight loss after 12 weeks, Resolution of comorbidities after 12 weeks, and 1 more.
This study contributes evidence to
Primary intervention
Gastric bypass
Primary outcomes
Evidence topics
Primary intervention
Intervention and outcome relationships this study adds to the evidence network.
Editorial context
See why this paper is useful beyond its individual results.
Evidence network role
This section describes how the study fits into the current evidence network. It does not determine whether an intervention works on its own.
2
Related topics
8
Evidence pairs
14
Related studies
Evidence topic
Contributes evidence
Evidence topic
Contributes evidence
Save studies and evidence pages, organize your personal Evidence Tracker, and keep the research you care about in one place.
Primary evidence
Evidence topic
matched_intervention
Related evidence
Evidence topic
Save evidence
Core evidence
The primary outcomes reported in this study.
Gastric bypass → Change in body composition after 12 weeks of treatment
Gastric bypass → Change in body composition after 12 weeks of treatment
Gastric bypass → Percentage weight loss after 12 weeks
Gastric bypass → Percentage weight loss after 12 weeks
Gastric bypass → Resolution of comorbidities after 12 weeks
Gastric bypass → Resolution of comorbidities after 12 weeks
Gastric bypass → Total weight loss after 12 weeks
Gastric bypass → Total weight loss after 12 weeks
Very-low-calorie ketogenic diet → Change in body composition after 12 weeks of treatment
Very-low-calorie ketogenic diet → Change in body composition after 12 weeks of treatment
Very-low-calorie ketogenic diet → Percentage weight loss after 12 weeks
Very-low-calorie ketogenic diet → Percentage weight loss after 12 weeks
Very-low-calorie ketogenic diet → Resolution of comorbidities after 12 weeks
Very-low-calorie ketogenic diet → Resolution of comorbidities after 12 weeks
Very-low-calorie ketogenic diet → Total weight loss after 12 weeks
Very-low-calorie ketogenic diet → Total weight loss after 12 weeks
Evidence Library
Save research, organize studies, and quickly find important evidence again.
Evidence Library
Save research, organize studies, and quickly find important evidence again.
Explore related studies, evidence collections, and research questions.
Relationships organized using the Dediabetes Evidence Intelligence™ framework.
This study contributes to evidence on Bariatric Procedures and Change in body composition after 12 weeks of treatment, Bariatric Procedures and Percentage weight loss after 12 weeks.
This study contributes to the evidence on the following intervention-outcome relationships.
Curated evidence collections and hubs this study is part of.
All studies on Bariatric Procedures
Contributes to Bariatric Procedures evidence base.
All studies measuring Change in body composition after 12 weeks of treatment
Measures Change in body composition after 12 weeks of treatment as a key outcome.
All studies measuring Percentage weight loss after 12 weeks
Measures Percentage weight loss after 12 weeks as a key outcome.
Latest published studies
Published within the last 2 years.
Jump to pre-filtered views in Evidence Explorer.
1 results
1 results
1 results
1 results
1 results
Generated from the study's connected evidence using Evidence Intelligence™.
Current evidence does not show a clear benefit of Gastric bypass for Change in body composition after 12 weeks of treatment.
ConsistencyScore™: Consistency cannot yet be determined from the available evidence.
Ranked evidence signals
Change in body composition after 12 weeks of treatment
EvidenceScore™ Emerging | EvidenceScore™ 59.0 | neutral | ConsistencyScore™ Unclear | 1 study
Why this answer: This answer is based on a single supporting study.
Limitations
Current evidence does not show a clear benefit of Gastric bypass for Percentage weight loss after 12 weeks.
ConsistencyScore™: Consistency cannot yet be determined from the available evidence.
Ranked evidence signals
Percentage weight loss after 12 weeks
EvidenceScore™ Emerging | EvidenceScore™ 59.0 | neutral | ConsistencyScore™ Unclear | 1 study
Why this answer: This answer is based on a single supporting study.
Limitations
Current evidence does not show a clear benefit of Gastric bypass for Resolution of comorbidities after 12 weeks.
ConsistencyScore™: Consistency cannot yet be determined from the available evidence.
Ranked evidence signals
Resolution of comorbidities after 12 weeks
EvidenceScore™ Emerging | EvidenceScore™ 59.0 | neutral | ConsistencyScore™ Unclear | 1 study
Why this answer: This answer is based on a single supporting study.
Limitations
Current evidence does not show a clear benefit of Gastric bypass for Total weight loss after 12 weeks.
ConsistencyScore™: Consistency cannot yet be determined from the available evidence.
Ranked evidence signals
Total weight loss after 12 weeks
EvidenceScore™ Emerging | EvidenceScore™ 59.0 | neutral | ConsistencyScore™ Unclear | 1 study
Why this answer: This answer is based on a single supporting study.
Limitations
Next steps
Choose a next path through related evidence topics, Evidence Explorer views, and research summaries.
Follow the topics this study contributes to.
Open broader Evidence Explorer views for this relationship.
Read related research summaries.
Focused on evidence, not advertising.
Your data is always protected.
New studies added every day.
