Extensive Weight Loss Prior to Bariatric Surgery is Associated with Worse Outcomes

Weight loss has been shown to favorably affect obesity-related comorbid disease. 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 includes a calorie-restrictive preoperative diet.

To evaluate the association between extensive preoperative weight loss and perioperative outcomes in patients undergoing bariatric surgery.

To determine optimal weight loss prior to bariatric surgery, we compared patients who lost over 10% of their highest weight preoperatively to patients who did not within the MBSAQIP database from 2015 to 2021, which included over 1.3 million patients.

Patients who lost more than 10% of their highest preoperative weight were more likely to experience postoperative complications, including reoperation (1.40% vs. 1.21%, p<.001), bleeding (0.85% vs. 0.67%, p<.001), emergency department visits (7.11% vs. 6.57%, p<.001), and dehydration (3.92% vs. 3.61%, p<.001). These differences remained significant with multivariable logistic regression analysis controlling for multiple patient factors and procedure type. Patients who lost more than 10% of their highest preoperative weight were also found to have a higher mortality (0.10% vs. 0.08%, p=.04) and readmission (3.92% vs. 3.60%, p<.001), however after multivariable logistic regression analysis these two findings did not retain their statistical significance.

Preoperative weight loss prior to bariatric surgery may be beneficial, however over 10% preoperative weight loss is associated with worse outcomes and should be cautioned.