Writing in the British Journal Of Sports Medicine, they said poor diet now generates more disease than physical inactivity, alcohol and smoking combined.

The editorial, by a group of cardiologists and sports experts, says that while obesity has rocketed in the past 30 years there has been little change in physical activity levels.

"This places the blame for our expanding waistlines directly on the type and amount of calories consumed," they write.

The authors, who include Dr Aseem Malhotra, a cardiologist and adviser to the campaign group Action on Sugar, said the public had been sold a “false perception” that exercise was more important than eating healthily, when the opposite was true.

Dr Malhotra said US data which tracked obesity and activity levels found little change in activity levels over two decades, while obesity levels soared.
In Britain, 25 per cent of adults are now obese, compared with less than 3 per cent in the 1970s.

Activity levels have not been tracked consistently over the same period, but data from the 1990s and 2000s suggests exercise levels could even be increasing.

The editorial accuses the food industry of promoting the idea that exercise matters more than food, in tactics described as “chillingly similar” to those of the tobacco industry.

It also attacks the sports industry for links with junk foods, and accuses health clubs and gyms of giving sugary snacks and drinks “a health halo” by selling them on their premises.