A Comparison of the Effects of Roux-en-Y Gastric Bypass and Sleeve Gastrectomy on Body Mass Composition as Measured by Air Displacement Plethysmography

  • Rhys Kavanagh
  • Jessica Smith
  • Emily Avgenackis
  • Dana Jones
  • Peter NauEmail author
Original Contributions



The laparoscopic sleeve gastrectomy (LSG) is now the most commonly performed bariatric surgery in the world. Multiple studies have demonstrated the equivalence between the LSG and Roux-en-Y gastric bypass (RYGB) with regard to weight loss and comorbidity resolution. Few studies have examined the differences in body mass composition change between the two procedures.


Sixty-three patients undergoing either LSG or RYGB underwent calculation of total body mass, ideal body mass, lean mass, and fat mass by air displacement plethysmography (BodPodtm) prior to surgery and at 12 months postoperatively. Calculations of excess body weight, % excess weight loss, change in % fat mass, and change in % lean mass were then performed at each time interval.


Thirty-three patients underwent LSG and 30 patients underwent RYGB. Mean percent excess weight loss in the LSG and RYGB group was 47.2% and 53.4% respectively (p = 0.165, 95% CI − 14.8–2.6). Mean percent change in fat mass for the LSG group and RYGB group was 9.2% and 10.51% respectively (p = 0.249, 95% CI − 0.86–3.2). Mean percent change in lean mass for the LSG group and RYGB group was 9.4% and 10.49% respectively (p = 0.383, 95% CI 2.85–1.13).


The LSG and RYGB both impart dramatic meaningful loss in excess body weight. In addition, both the LSG and RYGB impart dramatic reductions in fat mass. However, both procedures induce loss of lean mass and there appears to be no difference between the two procedures in this regard despite their anatomic and physiologic differences.


Bariatric surgery Body composition Gastric bypass Sleeve gastrectomy 


Funding Information

This project was supported by a research grant from Medtronic Surgical Innovations External Research Program (grant number 17448000).

Compliance with Ethical Standards

Data collection and patient investigation were performed following official review and IRB approval (IRB ID No. 201310819). In all cases, informed consent was obtained from the individual participants included in the study.

Conflict of Interest

The authors declare that they have no conflicts of interest.


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Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Roy J. and Lucille A. Carver College of MedicineIowa CityUSA

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