Estimates by Cancer Research show seven in 10 so-called millennials – those born between the early 1980s and mid-1990s – will be overweight by the time they are 35, making them the heaviest generation since records began.
By contrast, just five in 10 baby boomers – those born between 1945 and 1955 – were overweight or obese at the same age.
The disturbing statistics lay bare the health timebomb threatening Britain.
Adult obesity is linked to 13 different types of cancer, including breast, bowel and kidney, yet only 15 per cent of people in the UK are aware of the link.
Cancer Research UK’s director of prevention Alison Cox said: “Being overweight is the UK’s biggest cause of cancer after smoking, but most people don’t know about this substantial risk.
“The Government must play a part to help people make healthy food choices.”
The health warning comes just days after the Daily Express revealed research showing junk foods like pizzas, ready meals, cakes and crisps increase the risk of a disease that kills 162,000 Britons every year.
Obesity is estimated to cause 18,100 cancer cases each year in the UK and costs the economy £47billion.
Danger lurks in industrially-processed products like sugary snacks, cereals and reconstituted meat products with high levels of sugar, fat and salt, but lacking vitamins and fibre.
The hit list includes favourites like manufactured noodles, pre-packaged bread, ready-to-eat desserts, meatballs and chicken nuggets and artificially-sweetened fizzy drinks.
A 10 per cent dietary increase in “ultra-processed foods” was associated with a 12 per cent increased risk of cancer and is storing up a future health catastrophe.
In a fresh war on obesity today, Cancer Research UK is pressing for a ban on junk food adverts before the 9pm watershed.
The charity’s prevention expert Professor Linda Bauld said: “Extra body fat doesn’t just sit there, it sends messages around the body that can cause damage to cells.
“This damage can build up over time and increase the risk of cancer in the same way that damage from smoking causes cancer.”
Dietitians have long warned that our obsession with takeaways explains why Britain has seen a sharp increase in the number of lifestyle-driven cases of Type 2 diabetes.
Describing the figures as “horrifying”, Tam Fry of the National Obesity Forum said: “They are the result of successive governments paying only lip service to tackling an obesity crisis which was already making headlines 20 years ago.”
Prof Louis Levy, head of nutrition science at Public Health England, said: “We know overweight and obese children are likely to be the same when they become adults.
“One of our major contributions to tackling child obesity is to review the model underpinning restrictions on advertising to children.”