Oldmachar is one of 15 schools taking part in the first phase of the health promoting school initiative and the first to alter meals contracts.
Aberdeen has established education as the lead department in its strategy on health and physical activity and an updated policy will be in schools after Easter.
Stephanie Allison, the city's health promotion co-ordinator, said: "It will look at a whole-school approach to various issues, including diet. It will examine advertising on vending machines, support for parents on packed lunches and snacks and tuck shops.
"It also looks at what we teach in the classroom. We have to practise what we preach."