A twice-weekly limit on chips as well as a ban on chocolate could be brought into schools, as part of an £8.4m Welsh Assembly Government initiative.
Children and young people were asked their views on healthy eating
The radical changes being unveiled by the Education Minister Jane Hutt could mean pupils will be offered fruit and vegetables twice a day.
The plans are aimed at cutting child obesity and improving children's long-term eating habits and health.
But there are concerns some councils might struggle to fund the reforms.
In recent years the issue of school dinners has frequently made headlines, with campaigns for healthier eating led by Jamie Oliver.
Last September, the celebrity chef backed a scheme by Denbighshire council to stop pupils leaving the school premises at lunchtime to stop children eating unhealthily.
Recommended standards for school lunches in Wales
Oily fish on the menu at least once every two weeks
No less than two portions of fruit and vegetables per day per child
Chips and deep fried food not served more than twice a week
Reformed/reconstituted meat should not be served
A variety of breads should be encouraged including wholemeal bread
Sweets, crisps and chocolate banned
Restricted salt in cooked food
Source: the Welsh Assembly Government's Appetite for Life Action Plan
The assembly government's latest scheme aims to provide healthy food for all school children, but it could take up to two years before some pupils' eating habits are changed.
Initially, four local authorities will take part in a trial, with their findings used to help roll out the scheme to schools across the country.
Launching the action plan, Ms Hutt said: "All of us know the importance of a balanced diet and how essential it is to children and young people if they are to develop and grow into healthy adults."
The Chief Medical Officer for Wales Dr Tony Jewell said although general health was improving, he was concerned about the "rising epidemic" of obesity.
He said: "We must work hard to reverse this trend and it is therefore vital we encourage children to have a good diet and take regular physical activity when they are young so that they develop good habits they can take into adulthood. "
The assembly government has promised £6.6m to help schools meet the new standards.
But Professor Kevin Morgan, who is part of the Food in Schools group which drew up the Appetitive for Life document, warned local councils could face financial difficulties implementing the reforms.
"The big challenge is whether we can actually respond to what we call the "big squeeze". The big squeeze is rising costs on the one hand and falling take-up rates on the other," he said.
"That's economically unsustainable in the long-run."