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Updated: May 29, 2026

Roux-en-Y Gastric Bypass Operation in Rats
Published on: June 11, 2012
Bariatric surgery: impact on body composition after Roux-en-Y gastric bypass
Luana Azevedo de Aquino1, Silvia Elaine Pereira, Jacqueline de Souza Silva
1Center for Research on Micronutrients, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil. luana.nutri@gmail.com
Background:
The aim of this study was to analyze the impact of bariatric surgery on the body composition of patients suffering from class III obesity at different postoperative time intervals.
Methods:
The body composition of 114 patients undergoing Roux-en-Y gastric bypass surgery was measured prior to surgery (T0) and then 30 (T30) and 180 (T180) days following surgery. Body composition was evaluated using the following parameters: total body mass, body mass index, excess weight, percentage of excess weight loss, relative body fat (%F), lean body mass (LBM), and fat tissue mass (FTM). To determine these variables, validated formulas and equations proper to obese men and women were employed.
Results:
A significant reduction in %F (41.5%), LBM (20.3%), FTM (37.9%) was noted at each time interval (p ≤ 0.01).
Conclusions:
Bariatric surgery proved to be effective in reducing total body mass and body fat at every time interval. However, dietary measures emphasizing adequate protein intake may be implemented in order to reduce loss of LBM and, coupled with frequent physical activity, may help curtail the impact the surgery has on morphological variables.
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