As many as 700,000 new cases of cancer linked to being overweight or obese could be diagnosed during the next 20 years, warns a new report from Cancer Research UK and the UK Health Forum.

If current trends continue, almost three in four adults in the UK will be carrying excess weight by 2035, but the report also forecasts that more people will be obese than overweight by 2030 which, it says, is particularly concerning.

Aside from the impact on cancer numbers, the rising swell of expanding waistlines is also expected to cause millions of new cases of type II diabetes, coronary heart disease and stroke, which could cost the NHS an extra £2.5 billion over what it already spends on obesity-related disease by 2035.

On the flip side, the report also shows that small changes can make a big difference. A ‘mere’ one percent shift in the number of people going from overweight/obese to a healthy weight every year could prevent more than 64,000  cancer cases over the next 20 years, it said.

As such, Cancer Research UK is calling on the government to introduce a 9pm watershed ban on TV advertising of junk food as well as a 20p per litre tax on sugary drinks as part of a comprehensive children’s obesity strategy. “Obesity will be a huge burden to society and the NHS in the near future. We must act now to combat this threat,” said Alison Cox, the charity’s director of cancer prevention.

Celebrity chef and healthy eating activist Jamie Oliver said food education is key to reigning in the rising obesity trend. “We’re raising a generation of children in a society where junk food is cheap, widely advertised, and packed full of sugar_ so it's difficult to teach them how to make healthy choices. We need to give these kids a chance to be healthier adults - starting with a tax on sugary drinks to tackle obesity and diet-related disease in young people.”

Some carbonated drinks contain as much as 10 spoons of sugar. Research published in The Lancet Diabetes and Endocrinology this week claims that reducing the amount of sugar in drinks by 40% over five years could lead to one million fewer cases of obesity and 300,000 fewer cases of type II diabetes over 20 years. 

MPs also recently backed levy on full-sugar soft drinks in a bid to curb childhood obesity.