Many school cooking classes are based around cakes, muffins and desserts, according to new Kiwi research.
The Massey University research, commissioned by the Heart Foundation and vegetables.co.nz shows less than 50 percent of food prepared in class would be suitable for a "main meal".
"A lot of the foods being prepared were things like cakes, muffins and biscuits, so essentially your treat foods," Heart Foundation National Nutrition Advisor Angela Berrill told Newshub.
"There was a very small proportion of foods that were being prepared with the likes of fruit and vegetables."
The research also found only 10 percent of teachers surveyed considered fruit and vegetables as a key factor for choosing a recipe, which the Health Foundation said needs to improve.
"With rising obesity rates and with one-third of New Zealand children being overweight and obese, the cooking in school environment can be one of the key environments where we can help set our children up for healthier futures," Ms Berrill said.
She however acknowledged many schools are creating healthy menus as part of their food technology classes.
At Henderson Intermediate in Auckland, the focus is on whole foods.
Food technology teacher Robyn Lane says vegetables are a key part of what the students create.
"I say to my students, 'Half your plate should be vegetables'," she said.
"They think they might not like something but I tell them, 'Give it a go because you're growing up, your taste buds are growing up with you - give it another go'."
She said her students actually love vegetables and also grown them in their school garden.