Children are being put off eating healthy school meals by long queues and poor service, according to research by the Scottish Executive.
Noise and long waits were found to put children off school meals
A study of 52 primary schools found that pupils disliked queues and listening to shouting and other noise.
Youngsters said they understood the benefits of healthy food but did not usually prefer it.
The study was published as the Scottish Socialist Party launched plans for free school meals for all primary pupils.
The executive consultation with children aged five to 12 was carried out in June.
It found that many schools release children for lunch at the same time, instead of organising different sittings.
The study suggested this was one important reason why youngsters were put off school dinners.
Researchers also discovered that children may be more inclined to eat healthily if a reward system was introduced for making healthy food choices.
The findings state: "In general, children of both age groups know about and understand the importance of eating five portions of fruits and vegetables each day.
"However, many do not achieve this.
"Many children chose as their favourite food things which are considered unhealthy and, given the choice between healthy and unhealthy, they will tend towards the unhealthy option."
The report warned that uptake would remain low unless the environment, service and overall experience of eating school dinners was improved for children.
Factors singled out by children included noise, shouting, unappealing crockery and cutlery, long queues and the length of time involved.
In terms of healthy food, fish and salad were least appreciated, but pupils said they would be happy to see smoothies and exotic fruit like kiwi fruit and pineapples made more widely available.
The SSP's Free School Meals Bill has received support from headteachers, children's charities and religious leaders.
The bill had previously covered secondary pupils but would now only provide free meals in primary schools.
The party claimed the measure would cost an estimated £73m a year.
SSP MSP Frances Curran, who launched the plans, said: "Let's invest the £1.77 a day in our children's future rather than pay a much heavier price for ill health and drug billls later on."
The SNP welcomed the bill's publication as part of the nutiritious free school meals debate.
However Education Minister Peter Peacock dismissed it as a political stunt.
He claimed universal free meals would cost at least £180m and most of that would go to those who could afford to pay.