Health experts have warned the government to introduce a "fat tax" on unhealthy food to tackle the growing obesity epidemic.

A new report suggests that 46 per cent of British adults could be obese by 2030 – the equivalent of 11 million obese people in less than 20 years.

The results were published in The Lancet today.

This is a worrying trend because fat people are more likely to develop diabetes, heart disease and cancer – putting an extra strain on the NHS.

Obesity could end up costing the state £32 billion a year, a third of today's NHS budget.

Prof Steven Gortmaker, from the Harvard School of Public Health, said that taxing unhealthy food and drink would help slash obesity-related illnesses.

But the food industry has voiced its opposition to the idea.

Andrew Opie, food director at the British Retail Consortium, told the Telegraph: "There 's no such thing as an unhealthy food just an unhealthy diet. Demonising particular foods is not the answer. The tax regime already discriminates against many processed foods by subjecting them to VAT.

"Retailers are actively improving diets through education and providing healthier eating choices because that's what will make a difference.

"New taxes would just push up prices for hard – pressed households."

Anne Milton, the Health Minister, told the Telegraph: "We have no current plans to impose a 'fat tax', but we are working with food companies to reduce fat, sugar and salt and ensure healthier options are available."

She added: "We will be saying more about our plans to tackle obesity in a new document later this year."