The British Medical Association also urged a ban on TV advertising of junk food before the 9pm watershed. Dr Peter Tiplady, chairman of the BMA's public health committee, called for a joint approach to the problem.
"Schools should allow children to eat healthily and get enough exercise, but many have sold off their playing fields, installed junk-food vending machines and failed to provide healthy school meals," he said.
Dr Steve Watkins, deputy chairman of the same committee, added that it was "utterly and fundamentally wrong" for the food industry to encourage people to harm themselves for commercial purposes.
He said targeting children with high-fat, salt-laden and sugary foods was "utterly despicable". "It is important that we confine the advertisement of most processed foods to a time when they will not be promoted directly to children," Dr Watkins said.
The Commons health select committee has recommended voluntary action by advertisers to reduce the amount of unhealthy food targeted at youngsters.