New cases of obesity are rising fastest in younger adults in England, with diagnoses in those in their 30s increasing by nearly 20% between 2019-20 and 2024-25, according to a study published in The Lancet.

The findings are significant because obesity is a major risk factor for serious health conditions including diabetes, heart disease, and cancer. The trend towards earlier diagnosis in younger age groups is a cause for concern among health experts, despite the most common ages for diagnosis remaining the 40s and 50s.

For individuals aged 30 to 39, new obesity diagnoses rose to 24.1 per 1,000 people in 2024-25, up from 20.3 five years prior. Among those aged 20 to 29, new cases increased by 16%, reaching 20.3 per 1,000 people, compared to 17.5 in 2019-20. These increases outpaced those seen in older demographics.

Researchers also noted that earlier onset of obesity was more prevalent among non-white ethnic groups and in areas with higher levels of deprivation. While these demographic patterns are known, the acceleration of new cases among younger adults was unexpected.

Lead researcher Robert Fletcher suggested that adults in their 20s and 30s grew up during a period of significant expansion in the unhealthy food market, with widespread availability and advertising of fast food and takeaways. He also pointed to the impact of the COVID-19 pandemic and the subsequent cost of living crisis, suggesting that factors like childcare stress, working from home, and the rising cost of healthy food have made maintaining a healthy lifestyle more challenging for younger generations.

Sarah Perman from the Association of Directors of Public Health concurred, highlighting how unhealthy food options now dominate retail environments and are heavily advertised to young people from an early age. She noted that these less healthy foods are considerably cheaper and more accessible than nutritious alternatives. Research indicates healthy foods can be twice as expensive per calorie.

Katharine Jenner of the Obesity Health Alliance emphasized the cumulative effect of the environment young adults have experienced, which influences habit formation. She also suggested that the digital environment, including food apps and social media use, combined with pandemic-related disruptions to physical activity, may be contributing factors at a critical developmental stage.

The study, a collaboration between the University of Cambridge, the British Heart Foundation, and the George Institute for Global Health, analyzed 55 million adult NHS patient records to identify trends in new obesity diagnoses, excluding individuals already recorded as obese.