Effect of Ethnicity on Weight Loss After Bariatric Surgery

Zhamak Khorgami, Chi Zhang, Sarah E. Messiah, Nestor de la Cruz-Muñoz

Volume 25, Issue 5 Obesity Surgery

Key Takeaways

This study found that bariatric surgery produces significant weight loss for patients of all racial and ethnic backgrounds. Regardless of whether patients identified as Hispanic, Black, White, or another background, all groups achieved meaningful and life-changing weight loss after surgery.
The research also showed that the amount and pace of weight loss can vary somewhat depending on a patient's ethnic background. Understanding these differences helps Dr. de la Cruz-Muñoz set personalized, realistic expectations for each patient and tailor follow-up care to support the best possible outcome.
This article became the 5th most cited paper in the entire history of Obesity Surgery — a major international surgical journal — and was one of the most downloaded articles the year it was published. This level of impact means that surgeons and researchers around the world have relied on this study to guide their understanding of weight loss surgery outcomes.
Dr. de la Cruz-Muñoz is the senior author who led the research program that produced this study. His practice in Miami serves one of the most ethnically diverse patient populations in the country, and this research reflects his deep commitment to understanding how to deliver the best surgical outcomes for every patient, regardless of background.
For patients from Hispanic and Black communities — who are disproportionately affected by severe obesity but have historically had less access to weight loss surgery — this study provides reassuring evidence that bariatric surgery is effective across all ethnic groups, supporting the case for broader access to this life-changing treatment.

Abstract/Summary

This landmark study published in Obesity Surgery analyzed the effect of ethnicity on weight loss outcomes after bariatric surgery using a large national database. The study compared weight loss trajectories following metabolic and bariatric surgery across major racial and ethnic groups — including Hispanic, non-Hispanic Black, non-Hispanic White, and other racial/ethnic categories — to determine whether ethnicity independently influences surgical weight loss outcomes. The analysis demonstrated that while all racial and ethnic groups achieved clinically significant weight loss following bariatric surgery, there were measurable differences in the magnitude and trajectory of weight loss across ethnic groups, with important implications for patient counseling, outcome expectations, and postoperative follow-up strategies. This paper became one of the highest downloaded articles of its publication year and subsequently achieved the distinction of being the 5th most cited article in the entire history of Obesity Surgery — the official journal of the International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO). This extraordinary citation impact reflects the paper's foundational contribution to the field's understanding of how race and ethnicity influence bariatric surgery outcomes, a topic of critical importance given the disproportionate burden of severe obesity among Hispanic and non-Hispanic Black populations. Dr. de la Cruz-Muñoz is the senior and corresponding author, reflecting his leadership of the research program at the University of Miami that produced this work and his mentorship of Dr. Khorgami, who served as the first author.

In-Depth Review

Why This Study Was Needed

Earlier studies had reported that Hispanic and non-Hispanic Black patients lose less weight after bariatric surgery than non-Hispanic White patients. Almost all of those studies came from places where White patients were the majority and minority patients were a small share of the program. That raised a question: were the differences biological, or did they reflect access, culture and the environment patients lived in? Miami, where Hispanic residents are the majority, offered a unique setting to find out.

How the Study Was Done

The team reviewed 3,268 patients who had Roux-en-Y gastric bypass or an adjustable gastric band with Dr. de la Cruz-Muñoz’s program between 2002 and 2012: 1,561 Hispanic, 660 non-Hispanic Black and 1,047 non-Hispanic White. Excess weight loss (EWL) and BMI change were compared at 6, 12 and 24 months, and the analysis was repeated by sex, operation and starting BMI.

What the Study Found

Average excess weight loss (Hispanic / non-Hispanic White / non-Hispanic Black):

6 months: 52.7% / 49.7% / 43.0%
1 year: 66.0% / 64.0% / 54.1%
2 years: 68.6% / 69.5% / 57.6%

After gastric bypass, Hispanic and non-Hispanic White patients lost essentially the same amount of weight.
Non-Hispanic Black patients lost less on average, across sexes, operations and BMI categories, though still a clinically meaningful amount.
Patterns were similar but less pronounced after gastric banding; White patients outperformed Hispanic patients only after banding with a BMI above 40.

What This Means for Patients

In a community where Hispanic patients are the majority, they did just as well as White patients, which suggests that earlier gaps reported elsewhere were driven largely by social and environmental factors rather than biology. Every group in this study achieved substantial weight loss. Differences in averages should never be a reason to deny anyone surgery; they are a reason to tailor support and follow-up. Read more about why weight loss is not fair and realistic results after surgery.

Ethnicity also matters for eligibility: the 2022 ASMBS/IFSO guidelines recognize that some populations develop obesity-related disease at lower BMI levels.

Clinical Pearls

Gastric bypass produced equivalent weight loss in Hispanic and non-Hispanic White patients through two years.
Non-Hispanic Black patients lost less on average, independent of sex, operation or starting BMI.
Gastric bypass outperformed gastric banding across ethnic groups.
Social context, not just biology, likely shapes weight outcomes after surgery.

Strengths and Limitations

This is one of the largest single-program studies of ethnicity and weight loss, performed in a majority-Hispanic setting where most earlier research could not be done. It is retrospective, limited to two years of follow-up, and did not measure the social factors (income, diet, support, access to follow-up) the authors believe explain the differences. It has become one of the most cited papers on the subject in the journal’s history.

Expert Commentary

We wrote this paper because I did not see in my own practice what other studies were reporting. My Hispanic patients were doing very well. When we finally looked at more than 3,000 patients, the data confirmed it.

The lower average in our Black patients is a call to action, not a verdict. It tells us to invest more in follow-up, nutrition support and community resources, and to make sure no patient is discouraged from surgery because of a statistic.

— Dr. Nestor de la Cruz-Muñoz

Related Research

Khorgami Z, Zhang C, Messiah SE, de la Cruz-Muñoz N. Effect of Ethnicity on Weight Loss After Bariatric Surgery. Obesity Surgery. 2015;25(5):769-776. PMID: 25430619.