A government-commissioned study into school food has called for a crackdown on packed lunches in a bid to increase take up of school dinners.

The School Food Plan, written by the founders of the Leon restaurant chain, has urged ministers to roll out free school meals for all primary school children, although the authors acknowledge the government’s reluctance to do so.

The report urges headteachers to ban sugary drinks, crisps and confectionery, or offer incentives for bringing in a healthy lunch. It also backs schools which ban packed lunches outright.

“Many parents mistakenly imagine that a packed lunch is the healthiest option. Only 1% of packed lunches meet the nutritional standards that currently apply to school food,” the authors said.

“The vast majority of packed lunches are simply not nutritious enough. This is not a matter of opinion, but of empirical fact.”

Welcoming the plan, education secretary Michael Gove said: “What I’d like to see is more children eating school lunches and fewer having packed lunches, and more children feeling healthier and more energetic throughout the day.”