Obesity doesn’t equate to ill health: why the ‘disease’ label doesn’t always fit

People with the same body mass index can have radically different health statuses. Credit: Hiraman/Getty Nearly one billion people worldwide live with obesity 1 . Yet the scientific community is divided over what obesity means for health. For decades, obesity was viewed mainly as a health risk, increasing the likelihood of diabetes, cardiovascular disease and premature death 2 . But in the past few years, it is being increasingly described as a chronic disease, a shift that reflects efforts to reduce stigma and improve access to care long denied to people living with obesity 3 , 4 . If it were to be adopted formally by policymakers and clinicians, a uniform disease label would classify one in three adults in many high-income countries 1 as having the same chronic illness. Each would be potentially entitled to lifelong treatments, from weight-loss drugs to bariatric surgery and specialist follow-up. Why BMI is flawed — and how to redefine obesity Yet even people with obesity who have the same body mass index (BMI) — a measurement of weight divided by height squared, used to assess whether someone has obesity — can have radically different health statuses and trajectories 2 , 5 . Some people might struggle with heart failure, breathlessness and limited mobility. Others might remain in good health long term or even throughout their lives. The experiences, prognosis and treatment needs of these two groups differ profoundly. …