Piling on the pounds before the age of 30 could almost double risk of early death, a study found. Research involving 620,000 adults found people typically gained around one pound a year between the ages of 17 and 60. But the health consequences were far greater for those who became obese in their 20s than those who succumbed to middle-aged spread later.

Men who became obese before the age of 30 saw their risk of early death rise by 79%, while woman saw an 84% increase, compared with those who did not. Lead researcher Huyen Le, from Lund University in Malmö, Sweden, said the findings were important because most weight gain tends to occur in early adulthood.

This often coincides with when people in their early 20s leave home and become more reliant on junk food and convenience foods. 

Ms Le said: “The key message from this study is clear: avoiding weight gain — especially in your late teens and 20s — can have a major impact on your long-term health.

“Gaining weight early in adulthood, or developing obesity at a young age, is linked to a higher risk of dying from many chronic diseases later in life.”

On average, male participants in the study were tracked for 23 years, and female participants for 12 years. 

Those who gained weight later in life also saw an increased risk, but to a far lesser extent. Becoming obese between the age of 45 and 60 increased overall risk by around one quarter.

And reaching this threshold between the age of 30 and 45 increased the risk by 52%. Among the under 30s, every pound gained per year increased risk of early dearth by 24% in men and 22% in women.

Experts said the years between 17 and 30 were a “critical life stage” when building healthy habits can have lasting benefits.

Senior researcher Professor Tanja Stocks said: “Even modest weight gains in your 20s can significantly increase the risk of early death if they persist over several years.

“The earlier people embrace healthy living, the better the chance of a long life.”

The findings were presented at the European Congress on Obesity in Malaga, Spain, on Monday.

Katharine Jenner, director of the Obesity Health Alliance, said the study should be “yet another wake-up call” for the Government to take tougher action on obesity.

She added: “Gaining excess weight early in life doesn’t just increase the risk of obesity — it can shorten lives by driving up rates of type 2 diabetes, heart disease, certain cancers, and poor mental health. 

“Many young people are on course to reach obesity by 30, driven by a food environment dominated by fast food deals, oversized portions, and highly processed products. 

“This is the consequence of decades of failure by the commercial food system and the lack of action by Government to fix it.

“We need bold action to make healthy food the easy, affordable, and appealing choice.”