Obesitys Escalating Health Toll: New Study Highlights Risks across Severity Levels

Obesity continues to surge across the United States and is projected to rise steadily over the next 25 years.1 While it is widely known to increase the risk of chronic illness, a recent study published in the NEJM Evidence provides a more comprehensive understanding of its far-reaching impact, especially in individuals with more severe obesity.

The study analyzed data from 270,657 adults in the *All of Us* research program, focusing on those with a body mass index (BMI) of 18.5 or higher. Researchers assessed the prevalence and development of 16 obesity-related health conditions, including hypertension, type 2 diabetes, chronic kidney disease, heart failure, obstructive sleep apnea, fatty liver disease, and osteoarthritis. The cohort was notably diverse, with 62% women and 22% Black participants.

A clear, graded relationship emerged between BMI and disease risk. As obesity severity increased from Class I to Class III, the likelihood of developing these conditions rose significantly. Class III obesity (BMI ≥40) showed the strongest associations with obstructive sleep apnea, type 2 diabetes, and fatty liver disease, with hazard ratios exceeding 6 to 10 times that of individuals with normal BMI. Elevated risks were also noted for asthma, osteoarthritis, and cardiovascular disease. These patterns held regardless of sex or race.

Researchers calculated the proportion of cases that could be attributed to obesity. They found that excess weight accounted for more than half of obstructive sleep apnea cases and a notable share of osteoarthritis cases in the population.

The study offers one of the most detailed assessments to date by evaluating both existing and new cases of 16 conditions in a large, diverse cohort. It revealed that higher levels of obesity consistently correlate with greater health risks, underscoring the urgent need for targeted strategies in prevention, early intervention, and long-term obesity management.

Source:

1. Anderer S. Higher BMI Linked With Increased Risk Across Numerous Conditions. JAMA. Published online April 25, 2025. doi:10.1001/jama.2025.4677. Available on: https://jamanetwork.com/journals/jama/article-abstract/2833401?widget=personalizedcontent&previousarticle=0

2. Yao Z, Tchang BG, Albert M, Blumenthal RS, Nasir K, Blaha MJ. Associations between Class I, II, or III Obesity and Health Outcomes. NEJM evidence. 2025 Mar 25;4(4):EVIDoa2400229. doi: 10.1056/EVIDoa2400229. Available on: https://evidence.nejm.org/doi/abs/10.1056/EVIDoa2400229