Severe Obesity Tied to Increased Risk of 16 Common Health Conditions: Study

A new study has found that obesity, particularly severe obesity, is strongly associated with the incidence of 16 common health outcomes. Associations remained consistent across sex and racial groups. Strong associations were observed for obstructive sleep apnea, type 2 diabetes, and metabolic dysfunction-associated steatotic liver disease. The findings are published in NEJM Evidence.

Researchers conducted a longitudinal cohort study to understand how different levels of obesity relate to a wide array of health conditions across a diverse U.S. population. Data were analyzed from 270,657 participants enrolled in the All of Us research program.

Participants contributed electronic health records, physical measurements, and survey data. Body mass index (BMI) was calculated at enrollment and used to classify individuals as normal weight, overweight, or obese, with further stratification into obesity classes I, II, and III.

Sixteen pre-identified health conditions were evaluated: hypertension, type 2 diabetes, hyperlipidemia or dyslipidemia, heart failure, atrial fibrillation, atherosclerotic cardiovascular disease, chronic kidney disease, pulmonary embolism, deep vein thrombosis, gout, liver disease linked to metabolic dysfunction, biliary calculus, obstructive sleep apnea, asthma, gastroesophageal reflux disease, and osteoarthritis.

Obesity was present in 42.4% of the study population, including 21.2% with class I obesity, 11.3% with class II, and 9.8% with class III. Compared to those with normal weight, individuals with obesity were more likely to be female, Black, have lower income and education levels, and have higher blood pressure and waist-to-hip ratios.

Prevalence and incidence rates increased progressively with higher obesity classes for all 16 health outcomes. Observed associations with class III obesity were strongest for obstructive sleep apnea, type 2 diabetes mellitus, and metabolic dysfunction–associated liver disease. Weaker associations were found for asthma, osteoarthritis, and atherosclerotic cardiovascular disease.

Increased risk, particularly at higher severity levels, was associated with all 16 health outcomes studied. Risks rose in a stepwise manner across obesity classes, with the highest burden observed among individuals with class III obesity.

Reference: Christopher N. Schmickl,, Janna Raphelson,, Atul Malhotra, Forty Percent and Rising — Why Every Specialist Must Care about Obesity, NEJM Evidence, 4, 4, (2025)./doi/full/10.1056/EVIDe2500054