Background

Limited weight loss has been shown to favorably affect obesity-related comorbid disease and prior studies have shown that a 10% preoperative weight loss is associated with fewer complications after gastric bypass surgery. Although the optimal preoperative preparation for bariatric surgery is not standardized, prerequisite weight loss prior to bariatric surgical procedures is often mandated, typically around 10%, and may include very low or low-calorie preoperative diet.

Methods

To determine optimal weight loss prior to bariatric surgery, we compared patients who lost over 10% of their highest weight prior to surgery to patients who did not in MBSAQIP database from 2015-2021 which included over 1.5 million patients.

Results

Patients who lost more than 10% of highest preoperative weight were more likely to experience complications including death (0.17% vs 0.1%, p<.001), reoperation (2.04% vs 1.43%, p=.001), readmission (4.7% vs 3.85%, p=.001), bleeding (1.07% vs 0.74%, p=.001), emergency department visits (7.2% vs 6.58%, p=.001), and dehydration (3.64% vs 3.44%, p=.001). These differences remained significant with multivariate regression analysis controlling for multiple patient factors and comorbidites.

Conclusions

While preoperative weight loss prior to bariatric surgery may be beneficial, over 10% weight loss may be associated with worse outcomes and should be avoided.