Tessa Jowell, the Public Health minister, said it was essential to promote wholesome food such as vegetables, lean meat, rice and pasta in schools. She said schools had an important role in making sure that children from the poorest backgrounds had a healthy diet.
She was speaking at the launch of a consultation paper designed to improve the standard of school meals. The guidelines propose giving children fruit juice rather than fizzy drinks, offering salad and baked potatoes as an alternative to chips, and serving fish rather than meat at least once a week. But ministers insist the guidance will not rule out chips and chocolate cake.
More than a million children take free school meals. Ministers want to make sure that those who do not eat healthily at home learn good habits at school.
Ms Jowell said: "So many of the inequalities that blight the lives of adults in this country are set in childhood.
"Children from poorer families will characteristically tend to eat more fatty food and more sugar. We want to encourage the sort of balanced diet which is essential for their health and development.
"Children don't just learn facts and figures at school; they learn how to live as adults.
"Show me a healthy-eating child and I'll show you the healthy-eating adult."
The guidelines say school cooks should use reduced fat milk and dairy products, and that meat and poultry should be trimmed of fat.
Suggested menus include fishcakes or nutloaf with mashed potatoes and sweetcorn or salad, followed by fruit or jelly with frozen yoghurt.