About half of primary school children in the UK have a packed lunch.
But unlike school dinners, there are no official rules about what should be in them to make them nutritious.
And a new study from Leeds University found 98 in every 100 packed lunches eaten by children at primary school failed to meet nutritional standards.
Some schools set their own standards and even inspect lunchboxes and remove “contraband” unhealthy foods such as sausage rolls.
And one academy, in Norwich, recently suggested scrapping packed lunches for infants entirely to get more pupils eating their healthy school meals.
So what does a healthy packed lunch look like?
Experts say the “main event” should be something filling, such as bread, rice, pasta or potatoes. Choose wholegrain where