Scientists find: severe obesity increases risk of 16 common diseases

A new study conducted by scientists from Johns Hopkins University has shown that obesity, especially severe obesity, seriously increases the risk of developing 16 common diseases. And this link persists regardless of gender or race. The highest risks were found for sleep apnoea, type 2 diabetes and fatty liver disease.

Details: Zhiqi Yao et al, Associations between Class I, II, or III Obesity and Health Outcomes, NEJM Evidence (2025). DOI: 10.1056/EVIDoa2400229

According to experts, obesity is an increasingly common phenomenon in the United States. Projections suggest that by 2030, nearly half of the nation's adults will have a clinical diagnosis of obesity.

The study, published in the journal NEJM Evidence, analysed data from more than 270,000 participants in All of Us, the largest cohort study in US history launched by the National Institutes of Health.

The sample included data on height, weight, body mass index (BMI), medical records and surveys. People were divided into groups: normal weight, overweight and obese, which in turn was divided into three classes, I to III (the most severe).

The scientists studied the relationship between the degree of obesity and the following diseases: hypertension, type 2 diabetes, high cholesterol, heart failure, arrhythmia, coronary heart disease, chronic kidney disease, thrombosis, gout, liver obesity, gallstones, sleep apnoea, asthma, heartburn and osteoarthritis.

The results showed: the higher the degree of obesity, the greater the risk. Particularly strong links were found between degree III obesity and sleep apnoea (the risk is almost 11 times higher), diabetes (7.7 times higher) and fatty liver disease (6.7 times higher).

Even diseases such as osteoarthritis, asthma and atherosclerosis were less common, but still more common in obese people. The study also found that women, African Americans, and people with low income and education were more likely to be obese, and with it, the diseases in question.

Scientists emphasise that obesity is not just an appearance problem. It is a serious risk factor for many diseases and should not be ignored. Especially given the growing number of cases of severe obesity.

The authors estimate that up to 50 per cent of sleep apnoea cases and up to 36 per cent of liver disease are linked to obesity. This means that weight loss interventions can have a serious impact on the health of the nation as a whole.

As the number of obese people in the world grows, the findings will help to inform the development of new prevention programmes, clinical approaches and public health policies.