The food and soft drinks lobbies, battling to save their products from being banned in schools, took their case to parliament last week.
The Scottish Food and Drink Federation and the British Soft Drinks Association told MSPs, in effect: you can take children to water, but you can't make them drink. Both bodies were giving evidence to the parliament's communities committee, which is examining the Schools (Health Promotion and Nutrition)(Scotland) Bill. It will impose new duties on councils to comply with nutritional requirements, give ministers powers to ban junk food and allow councils to provide free milk again.
But the Scottish Food and Drink Federation warned that any sanctions on chips, chocolate and salty snacks would only make such foods more desirable, and children would buy them outside school or abandon school meals altogether.
The British Soft Drinks Association said hydration was important for good pupil behaviour and performance, and claimed too few children drank enough fluids as it was.
It said providing only water did not mean children would drink it. Their concerns echoed those from a leading expert on the other side of the fence.
Fergus Chambers, director of Direct and Care Services in Glasgow, which is responsible for school meals, told the parliament's finance committee earlier that a blanket ban would lead secondary pupils in particular to turn their backs on school meals.
Flora McLean, director of the Scottish Food and Drink Federation, said no food (even confectionary) should be banned. She told the communities committee the emphasis should be on encouraging pupils to eat more vegetables, fruit and starchy carbohydrates."
The federation wants the existing "target nutrient specifications", which caterers use to construct healthy weekly menus, to stay as guidance but not to become law.
But the British Dental Association said in evidence that action was essential to combat tooth decay which was greater in Scotland than in England and Wales. According to BDA figures, more than 60 per cent of three-year-olds from areas of severe deprivation in Scotland had dental disease.
However, some schools are already at the starting gate. Those in North Lanarkshire offer chips only once a week, and oily fish is on the menu weekly rather than once every three weeks as proposed in the bill.
David Craig, quality improvement officer in North Lanarkshire Council, nonetheless welcomed the bill: "It's not a panacea, but it will build on what's already been achieved with Hungry for Success."
A primary lunch should average 557 calories, with no more than 21.7 grammes of fat, and no more than 745 mg of sodium; secondary lunches should average 664 calories, with a maximum of 25.8 grammes of fat and no more than 894 mg of sodium.
Oily fish should be served at least once every three weeks, and meals should not contain deep fried foods more than three times a week - including chips.
Salt shakers should be banned from canteen tables, and condiments only provided in 10 ml portions.