Study finds extreme obesity common among bariatric surgery patients, should not preclude treatment

Patients with extreme obesity are more common among those undergoing metabolic and bariatric surgery than previously recognized, and although they face a greater burden of certain health conditions and surgical complications, their overall surgical risk remains relatively low, according to a new study led by researchers at LSU’s Pennington Biomedical Research Center.

The study, “Extreme Obesity (BMI ≥60 kg/m2) Characterization Up to and Beyond 80 kg/m2 in 1,262,454 Bariatric Surgery Patients,” published in the journal Obesity, analyzed 1,262,454 metabolic and bariatric surgery patients from 2015 through 2023 and found that 5.3% had extreme obesity, defined as a body mass index (BMI) of 60 kg/m² or higher. Patients with a BMI of 70 kg/m² or higher accounted for approximately 1.1% of surgeries annually, a proportion that remained relatively consistent throughout the nine-year study period.

The findings provide one of the most detailed clinical descriptions to date of patients with extreme obesity, a population that has historically been underrepresented in both medical research and clinical care. Extreme obesity is the fastest-growing subgroup of obesity in the United States, with more than 1.2 million Americans now having a BMI of 60 kg/m² or higher.

“Extreme obesity represents one of the most medically complex and understudied forms of obesity, yet these patients have been largely overlooked for decades,” said Dr. Vance Albaugh, a physician-scientist at Pennington Biomedical and lead author of the study. “This study brings much-needed attention to a growing population of patients who face substantial health risks and barriers to care, while also identifying important opportunities to improve treatment and outcomes.”

Researchers used data from the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP), the largest available clinical dataset for metabolic and bariatric surgery. The study included more than 1.79 million total cases, with 1,262,454 eligible cases included in the analysis.

Patients with the highest BMIs had a greater burden of several obesity-associated conditions. Among patients with BMI of 70 kg/m² or higher, 56.7% had hypertension compared with 46.9% of patients with BMI below 40. Sleep apnea was present in 59.6% compared with 34.6%, while chronic obstructive pulmonary disease and functional dependence were also more common among patients with the highest BMIs.

The study found that surgical complications increased as BMI increased, but the absolute risk remained low. Among patients with BMI of 70 kg/m² or higher, serious complications occurred in 2.57% of cases and mortality was 0.35%. Mortality was higher than among patients with BMI below 40, where it was 0.05%, but remained low in absolute terms.

“Extreme obesity presents substantial medical and surgical challenges, but it should not be viewed as a reason to deny patients effective treatment,” said Dr. Philip Schauer, a co-author of the study and director of the Metamor Institute at Pennington Biomedical. “Our findings show that, even at the highest levels of BMI, metabolic and bariatric surgery can be performed with relatively low rates of serious complications and mortality when patients are treated by experienced, multidisciplinary teams.”

The relationship between BMI and disease burden was not uniform across all conditions. Some conditions, including hypertension and sleep apnea, became more common as BMI increased, while others were more prevalent among patients with lower BMI. The researchers say the findings reinforce the need to better understand obesity as a complex disease with distinct subtypes rather than relying solely on broad BMI classifications.

The findings are particularly relevant in Louisiana, which has one of the nation's highest prevalences of severe obesity. Pennington Biomedical's Metamor Institute treats patients with severe and extreme obesity and provides an opportunity for researchers to study this growing population.

“At Pennington Biomedical, we have an opportunity to build on this work and are continuing to develop the infrastructure needed to better serve these patients,” Dr. Albaugh said. “We are working toward establishing a prehabilitation center that could become a nationally and internationally recognized hub for studying and caring for this growing group of patients. Our goal is to help patients improve their health and readiness for treatment while also advancing our understanding of the biology of extreme obesity.”

The researchers note that the study population represents only patients who underwent surgery. Individuals who were considered too high-risk for surgery, lacked access to care or never received a surgical consultation were not captured in the dataset. As a result, the study likely represents an underestimation of the population living with extreme obesity.

The researchers say the findings have implications beyond bariatric surgery. As the number of people living with very high BMI continues to grow, healthcare systems will need greater expertise, resources and specialized approaches to accommodate these patients. The study also highlights the importance of earlier intervention and multidisciplinary care.

Reference:

V. L. Albaugh, H. G. Navas, R. C. Ross, et al., “ Extreme Obesity (BMI ≥ 60 kg/m2) Characterization up to and Beyond 80 kg/m2 in 1,262,454 Bariatric Surgery Patients,” Obesity (2026): 1–13, https://doi.org/10.1002/oby.70289.