Key Summary
- New obesity diagnoses are up nearly 20 per cent for people in their 30s and 16 per cent for those in their 20s compared to five years ago.
- The acceleration of early-onset obesity is most pronounced in non-white populations and areas with the highest levels of economic deprivation.
- Researchers point to a "boom" in the unhealthy food market, digital food delivery apps, and the compounding financial stresses of the pandemic and cost-of-living crisis.
New obesity diagnoses have climbed most steeply among younger adults in England, according to a study published in The Lancet.
Researchers who analysed 55 million NHS adult patient records found that in 2024-25 people aged 30-39 had nearly 20 per cent more new obesity diagnoses than in 2019-20, rising to 24.1 new cases per 1,000 from 20.3.
For those aged 20-29 the rate increased by 16 per cent, from 17.5 to 20.3 per 1,000. While the highest absolute numbers of diagnoses remain in people in their 40s and 50s, the fastest increases were concentrated in younger age groups; rates fell among people aged 60-79.
The study also revealed sharp disparities by ethnicity and deprivation. Earlier onset of obesity was more common among non-white groups and in the most deprived areas, echoing long-standing patterns of unequal health outcomes that researchers say appear to have accelerated recently.
Lead author Robert Fletcher said the study did not test causes directly but highlighted three likely contributors: prolonged exposure during formative years to an expanding market for unhealthy foods, widespread advertising and the proliferation of takeaways; the disruptive effects of the COVID-19 pandemic on daily routines and activity; and the subsequent cost-of-living squeeze that made healthier choices harder to afford.
Public health figures echoed those concerns. Sarah Perman of the Association of Directors of Public Health noted that unhealthy options now dominate supermarkets, corner shops and fast-food outlets, while research from the Food Foundation shows healthier foods cost about twice as much per calorie as less healthy alternatives.
A study had also found a link between long working hours and increased risk of obesity.
Katharine Jenner of the Obesity Health Alliance added that habit-forming behaviours shaped in a largely digital food environment - including heavy use of delivery apps and social media - likely played a role, with the pandemic interrupting activity at a critical stage for younger adults.
The researchers excluded patients already recorded as obese to focus on new diagnoses. Overall, the share of people recorded as obese rose from 26.2 per cent to 30.3 per cent over the study period.
The team suggested that declining new-case rates among older adults may partly reflect greater private access to weight-loss medications, since NHS availability remains limited.
Prof Sir Michael Marmot of University College London described the findings as worrying and said they provided further evidence that social inequalities widened after the pandemic.
A Department of Health and Social Care spokesperson said the government was taking action on obesity, pointing to forthcoming restrictions on junk-food advertising and targets to boost healthy food sales.
