Celebrity chef Jamie Oliver has joined health professionals and teachers to condemn the use of sporting role models to promote junk food.
A letter to The Times signed by Oliver and others including Royal College of Paediatrics and Child Health (RCPCH) president Dr Hilary Cass says the use of well-loved sports people to advertise junk food is sending the wrong message to children.
It reads: "On the eve of the London Olympics we, a group with a vested interest in improving the health and wellbeing of young people, express our grave concern about this trend.
"We believe it is wrong for athletes to encourage the excessive consumption of such items, which are fuelling poor health and obesity. David Beckham is a great sportsman, yet he has endorsed Pepsi. What about the impact of Gary Lineker's association with Walkers crisps? Or the partnership between Mars and the FA?"
It goes on: "Food companies, well aware that such foods have little redeeming nutritional qualities, are able to trigger the so-called 'halo' effect by associating them with sport. Yet diet-related diseases are reaching global epidemic proportions.
"With one in three children in Britain overweight or obese by the age of nine, we have a public health crisis that requires urgent intervention."
It ends: "We would ask athletes to be very conscious of the effect their endorsements may have on the future lives of youngsters. Obesity does not just carry physical consequences but serious social and emotional ones as well."
Other signatories to the letter are RCPCH past president Professor Terence Stephenson, National Association of Head Teachers president Steve Iredale, Children's Food Campaign director Charlie Powell and London cardiologist Dr Aseem Malhotra.
Dr Malhotra, who has called for a ban on junk food sponsorship of the Olympics, said: "It is totally perverse that some of the main sponsors of the greatest sporting spectacle in the world are McDonald's and Coca-Cola.
"One vital step in reducing the consumption of obesogenic products is to end the association of sporting role models with junk food. The very lucrative financial gain for these athletes is sadly at the expense of our children's health and we should not allow this to continue."