The Steep Health Toll of Rising Obesity Classes

A growing body of evidence shows that obesity is not a single condition, but a progressive driver of multisystem disease. Using data from more than 270,000 participants in the All of Us research program, this study provides one of the clearest pictures yet of how increasing obesity severity translates into escalating health risks.

With nearly one in ten participants living with Class III obesity, the analysis demonstrates striking, graded associations across 16 common health outcomes. Severe obesity carried the highest risk for obstructive sleep apnea, type 2 diabetes, and metabolic dysfunction–associated steatotic liver disease, with hazard ratios exceeding 6–10. Even conditions traditionally considered weakly linked to obesity—such as asthma, osteoarthritis, and atherosclerotic cardiovascular disease—showed meaningful increases in risk.

The consistency of these associations across sex and race underscores the broad relevance of the findings. Equally notable is the population-level impact: obesity accounted for up to half of all obstructive sleep apnea cases in this cohort.

These results reinforce a critical message—the health consequences of obesity escalate sharply with severity, and effective prevention and management strategies must keep pace with this rising burden. As rates of severe obesity continue to climb, translating such evidence into action becomes an urgent clinical and public health priority.