Background

Preoperative body mass index (BMI) has been shown to impact postoperative weight loss with bariatric surgery. However, it is unknown whether the effect is uniform between male and female sex or by procedure type.

Methods

Laparoscopic gastric bypass (LGB) and sleeve gastrectomy(LSG) cases between 2006-2021 were analyzed (n=97,793) using a state-wide bariatric specific data registry. Total body weight loss (TBWL%) at 1-year after surgery was compared between male and female sex based on preoperative BMI and stratified by procedure type.

Results

TBWL% was greater among females with lower preoperative BMIs (<50 kg/m2) for both LGB (34.1% vs. 32.2%, p<0.0001) and LSG (28.7% vs. 27.7%, p<0.0001). However, TBWL% was greater among males with higher preoperative BMIs (>50 kg/m2), for both LGB (36.8% vs. 35.5%, p<0.0001) and LSG (32.2% vs. 30.3%, p<0.0001) (Figure 1). Males with a BMI <50 kg/m2 were more likely to be older (49.5 years vs. 45.4 years, p<0.0001), have higher rates of hypertension (67.3% vs 45.1%, p<0.0001), hyperlipidemia (64.1% vs. 44.9%, p<0.0001) and diabetes (45.5% vs. 29.4%, p<0.0001), when compared to females with a BMI <50 kg/m2.

Conclusions

At lower BMIs, males have less weight loss when compared with females but also have higher rates of metabolic disease. However, at higher BMIs, females experience less weight loss, regardless of procedure type. Females appear to experience a weight loss plateau when the BMI >50 kg/m2, which warrants further investigation.