While exercise is essential for good health, it will not counteract the negative impact of a poor diet, experts have claimed.

They insisted that nobody can outrun a bad diet, even athletes.

According to the experts, while exercise has a key role in staving off diseases such as heart disease and diabetes, calorie-rich diets are now responsible for more ill health than physical inactivity, smoking and drinking alcohol combined.

They pointed out that many people believe that obesity is due to a lack of exercise, however this is simply incorrect. And the reason why people believe this is because of the work of corporate marketing, they stated.

They liken the marketing tactics of the food industry as ‘chillingly similar to those of Big Tobacco', which used many different methods to convince people that smoking was not related to lung cancer, including confusion, denial and ‘bent scientists'.

"Celebrity endorsements of sugary drinks and the association of junk food and sport must end. The ‘health halo' legitimisation of nutritionally deficient products is misleading and unscientific," they said.

They insisted that as part of this, health clubs and gyms must set an example by removing the sale of such products from their premises.

Meanwhile, the experts also pointed out that public health campaigns have tended to focus on maintaining a healthy weight through the counting of calories. This is not helpful, they said, because it is often the source of these calories that is more important.

"Sugar calories promote fat storage and hunger. Fat calories induce fullness or satiation," they noted.

In fact, the prevalence of diabetes increases 11-fold for every 150 additional sugar calories that are consumed on a daily basis, when compared with the same amount of calories as fat.

Furthermore, an increasing amount of evidence appears to suggest that carbohydrates have a role to play as well. Recent research indicated that reducing carbohydrates in the diet was very effective at reducing the risk of metabolic syndrome and should play a key role in the treatment of diabetes.

Metabolic syndrome refers to a group of conditions including obesity, high blood pressure and abnormal cholesterol levels, which combine to increase the risk of heart disease, stroke and diabetes. Having just one of these conditions increases your risk of a serious disease. However in metabolic syndrome, when all the conditions are present together, the risk is even greater.

"It's time to wind back the harms caused by the junk food industry's public relations machinery. Let's bust the myth of physical inactivity and obesity. You can't outrun a bad diet," the experts added.

The comments were made in the British Journal of Sports Medicine by Dr Aseem Malhotra, of Frimley Park Hospital in the UK, Prof Tim Noakes of the University of Cape Town in South Africa and Dr Stephen Phinney of the University of California, Davis, in the US.