Detailed evidence on what children eat for lunch should be served up by every school in Wales, according to Estyn.
The inspection body believes Wales should be following England and Scotland in making schools more accountable for healthy eating.
Its recommendations follow claims that Wales is lagging behind the rest of the UK in making dietary changes aimed at reducing rising obesity rates among the young. Under Estyn's proposals, published this week, inspectors would receive more training to advise schools on healthy eating. They would also routinely investigate what children eat during the school day.
There is not enough explicit reporting on healthy living, says Estyn's response to the Assembly government's "Appetite for life" consultation document published in June. Few inspection reports contain clear comments on healthy living and none mention school meals, it says.
A key proposal of "Appetite for life" was for a Wales-wide evaluation of school meals provision and a national database to chart progress. Estyn recommends the Assembly government ask it and the Food Standards Agency to carry out a baseline survey into healthy eating and drinking as part of their remit in 2007-08. Schools will also be encouraged to include how they promote healthy eating and drinking in their self-evaluations.
Susan Lewis, Her Majesty's chief inspector of education and training in Wales, said: "The survey will provide Estyn, the Food Standards Agency and schools with the opportunity to test new food and nutritional standards.
"We will check the standard of meals and snacks, find out what schools can do to provide a better service and look at how they can encourage a healthy diet."
An independent 'food in schools' working group was set up in Wales in July 2005 to look at the quality of school dinners. But by then every school in England was already expected to give evidence on its healthy eating schemes as part of its self-evaluation.
In Scotland, evaluations started in September 2004 to coincide with their 'hungry for success' initiative. There has also been an investigation into food served in Scottish primary schools.
The 'appetite for life' report contained 41 proposals and recommended that new meal standards be introduced in Wales over two years from September 2008.
School meals: advice on the role of inspection in monitoring school meal standards,www.estyn.gov.uk