Metabolic adaptation following gastric bypass surgery: results from a 2-year observational study
Authors' conclusion
These results suggest that there is a potential biological mechanism of surgery that attenuates the expected postoperative downregulation in BMR thus helping GBP patients maintain weight loss.
Study context
- Population
- GBP patients (77.4% female; mean BMI 45.5 [SD 7.0] kg/m²; age 47.4 [11.6] y) and comparators (50% female; BMI 27.2 [4.6] kg/m²; age 41.8 [13.6] y); evaluated 1 month pre-surgery and 3, 12 and 24 months post-surgery
- Participants
- 31 vs 32
- Exposure
- GBP patients vs weight-stable comparators
- GBPn = 31
- Comparatorsn = 32reference
- Outcome
- Metabolic adaptation: reduction in BMR not explained by changes in body composition (FM, FFM), vs weight-stable comparators
- Follow-up
- 3, 12 and 24 months post-surgery
Methodological details2-year, time-matched weight-stable comparator group, basal metabolic rate (BMR) by indirect calorimetry under standardised residential conditions; body composition by DXA; linear regression
- 2-year
- Time-matched weight-stable comparator group
- BMR by indirect calorimetry under standardised residential conditions; body composition by DXA; linear regression
Main finding
As reported in the abstract
Metabolic adaptation in GBP patients
- Metabolic adaptation present in rapid weight loss phase (6.9 kg/month at 3 months)
- p = 0.011
- Metabolic adaptation present in slower weight loss phase (1.6 kg/month, 3 to 12 months)
- p < 0.0001
- Metabolic adaptation present in weight maintenance phase (24 months)
- p = 0.00073
Observational data: associations, not effects.
Further findings
Body weight change · 24 months post-surgery
- Patients lost a quarter of their body weight, mainly fat mass (FM) (4:1 FM to fat-free mass (FFM) loss ratio)
- −25.6%(1.8%); p < 0.0001
Absolute BMR (MJ/d) · 24 months post-surgery
- Absolute BMR reduced after surgery, values similar to comparator group from 3 months post-surgery
- 25.7%
Associations of BMR change
- Positive associations between changes in BMR and changes in FFM and FM
- P < 0.03
Original publication
Metabolic adaptation following gastric bypass surgery: results from a 2-year observational study. Int J Obes (Lond). Published 3 September 2024. doi:10.
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