Men entered bariatric surgery sicker and lost slightly less weight

What happened

A Dutch research team analyzed 17,567 patients from the Netherlands' national bariatric surgery registry to answer a question no study had addressed directly before: do men, premenopausal women, and postmenopausal women fare differently after weight-loss surgery? The paper, published in Clinical Nutrition (April 2026) by van der Meer and colleagues with senior authorship from Amsterdam UMC and Yale School of Medicine, compared primary laparoscopic gastric bypass and sleeve gastrectomy cases performed in 2018-2019 with follow-up out to 24 months.

The short version for patients: about 80% of people getting metabolic bariatric surgery are women, but the smaller group of men who do have it tend to arrive at the operating table older in disease terms, with more diabetes and more cardiovascular risk, even though their BMI is actually lower on average. And after surgery, men lost somewhat less weight than premenopausal women did.

Of the 17,567 patients, 21.8% were men, 61.9% were premenopausal women, and 16.3% were postmenopausal women. Everyone had either a Roux-en-Y gastric bypass or a sleeve gastrectomy done laparoscopically between 2018 and 2019, tracked through a national registry with follow-up to two years.

One of the study's most useful observations is about where people started. Men and postmenopausal women had lower BMI before surgery than premenopausal women, yet carried substantially more disease: type 2 diabetes was present in 30.4% of men and 31.7% of postmenopausal women, versus 11.4% of premenopausal women. Rates of hypertension and dyslipidemia followed the same pattern. In other words, at an equal or lower body size, men and postmenopausal women showed up with more of the metabolic damage obesity causes.

Weight loss differed by group, and the difference persisted. Men's total weight loss was 28.2% (plus or minus 8.5) at 12 months and 27.9% (plus or minus 9.4) at 24 months, lower than what premenopausal women achieved. The authors report the differences were largely consistent across both operation types.

Complications also split along sex and menopause lines:

• Postmenopausal women had more severe complications than either other group: 6.2%, versus 1.7% in premenopausal women and 2.7% in men.
• Postoperative bleeding was more common in men (1.9%) and postmenopausal women (1.6%) than in premenopausal women (1.0%).

These are registry-level averages across all Dutch hospitals performing these operations in that period, not results from a single high-volume center.

Roughly four in five bariatric surgery patients are women, so most clinical experience, marketing, and peer support skews female. This is the first large registry study to quantify what that skew may be hiding: men who eventually reach surgery carry more diabetes at lower BMIs, and lose somewhat less weight afterward. If part of the explanation is delayed referral, the practical takeaway for male readers of this site is that waiting until weight or complications force the issue has a measurable cost.

What it means

For male readers considering surgery, the finding is not that surgery works poorly in men. A 28% total weight loss is a substantial result. The point is timing: men in this registry appear to reach surgery later in the course of their disease, with more diabetes and cardiovascular risk already established, despite weighing less than the women entering surgery. The authors explicitly frame this as an argument for earlier treatment and referral of men, whose abdominal-body-fat pattern accumulates metabolic risk before the scale shows very large numbers.

For women past menopause, the message cuts two ways: this group carried a heavy preoperative disease burden similar to men's, and had the highest rate of severe early complications (6.2%). That does not make surgery inappropriate for postmenopausal women, but it supports careful preoperative risk assessment and realistic conversations about early complication risk.

For programs, the data argue against eligibility rules built only on BMI thresholds. Two patients with the same BMI can arrive with very different metabolic disease depending on sex and menopause status.

What it does not mean

It does not mean a man should avoid surgery because "men do worse." Average differences hide wide individual variation, and the men's average result was still clinically meaningful.

It does not mean postmenopausal women should be refused surgery; the 6.2% severe-complication figure describes one national registry over two years, not a ceiling for any individual's risk at a specific program.

And it does not transfer automatically to the United States. This is a Dutch population with Dutch care patterns, a mostly white European cohort typical of that country's registries, and procedures done in 2018-2019. U.S. populations differ in ancestry, insurance-driven timing, and surgical technique mix. Registry studies like this one are also observational: they can show that groups differed, but they cannot fully separate biology from referral patterns, comorbidity at presentation, or surgical decision-making.

Finally, the study measured outcomes to 24 months. Longer-term differences, including weight regain, reflux after sleeve, or nutritional outcomes by sex, remain open questions.