Why are Obesity Cases Rising Fastest in Young Brits?

A study suggests that new cases of obesity are rising fastest among younger adults in England.

The study, published in The Lancet, found obesity diagnoses among people in their 20s and 30s have increased significantly since before the Covid-19 pandemic.

Researchers also identified notable differences between ethnic groups and levels of deprivation, with non-white communities and poorer areas experiencing steeper rises.

The findings have prompted concern among health experts, who warn that earlier obesity diagnoses could lead to more people developing serious illnesses at younger ages.

Researchers from the University of Cambridge, the British Heart Foundation and the George Institute for Global Health analysed 55 million NHS patient records to examine new obesity diagnoses across England.

The study found that among adults aged 30 to 39, there were 24.1 new obesity cases per 1,000 people in 2024-25, compared to 20.3 per 1,000 in 2019-20.

Among those aged 20 to 29, the rate increased from 17.5 to 20.3 new cases per 1,000 people over the same period. These represented the largest increases across all age groups.

Although obesity remained most commonly diagnosed among people in their 40s and 50s, researchers said the acceleration among younger adults was particularly concerning.

Lead researcher Robert Fletcher said the study did not investigate the precise causes behind the increase. However, he believes several factors may be contributing to the trend.

He said: “They have been surrounded by unhealthy food in their formative years.

“On our high streets, there has been a proliferation of takeaways and fast food outlets and unhealthy food has been heavily advertised as these age groups have been growing up.”

Fletcher also suggested the pandemic and subsequent cost-of-living crisis may have disproportionately affected younger adults:

“The stress of looking after children, while working from home and then being able to afford healthy food as inflation increased, has made healthier lifestyles more difficult,” he added.

Health leaders said the findings reflect broader problems within the UK’s food environment.

Sarah Perman, from the Association of Directors of Public Health, agreed that unhealthy food has become increasingly dominant in everyday life.

She said unhealthier options now dominate “our supermarkets, corner shops and fast food outlets”.

“From infancy, children and young people are bombarded with advertising that encourages an unhealthy diet.

“It is also far cheaper and easier for individuals to consume foods and drinks high in fat, sugar, and salt than healthier alternatives.”

Research by the Food Foundation has previously found that healthy foods cost around twice as much per calorie as unhealthy options, creating additional barriers for families trying to make healthier choices.

Katharine Jenner, of the Obesity Health Alliance, said younger generations have spent much of their lives in environments that encourage unhealthy eating habits.

She said the environment people in their 20s and 30s have grown up with has had a huge influence on “habit-forming behaviours”.

Jenner added that digital lifestyles may also be contributing to the rise.

Younger adults are more likely to use food delivery apps and spend significant time on social media, while pandemic restrictions disrupted exercise routines and other healthy habits at a “crucial moment”.

The study also found obesity rates increased overall during the five-year period. The proportion of adults recorded as obese rose from 26.2% to 30.3%.

However, researchers observed a different pattern among older adults. New obesity diagnoses fell among people aged between 60 and 79.

The team suggested this could be linked to the growing use of weight-loss medications, which older adults may be more able to afford.

Access to these treatments remains limited through the NHS, meaning some patients rely on private prescriptions.

Professor Sir Michael Marmot, one of the UK’s leading experts on health inequalities from University College London, described the findings as troubling.

He said the study provided “further evidence” that inequalities have widened since the pandemic.

Responding to the findings, a Department of Health and Social Care spokesperson said the government was taking “decisive action” to tackle obesity through measures including restrictions on junk food advertising and targets designed to encourage healthier food sales.