These are among the findings of the fifth school meals survey carried out by Gardner Merchant, which provides catering services in more than 400 schools.
The good news is that more encouragement is given for healthy eating in Scottish schools and the number of pupils who take part in food committee meetings is the highest in the UK. Nationally, only 46 per cent of pupils said their school encouraged healthy eating.
There was further reinforcement of success in the struggle towards healthy eating from the revelation that only 11 per cent of Scots said chocolate was their favourite packed lunch item against an average of 39 per cent.
Some 70 per cent of Scottish pupils discuss healthy eating in class compared with only 60 per cent nationally.
But, while chip consumption has fallen nationally from 2.9 times a week to 2.5, Scots youngsters remain the biggest chip consumers behind pupils in the north of England. The traditional pattern of three meals a day continues to be eroded as pupils give way to "grazing".
The company is piloting the concept of an "energy download zone", which offers snacks and meals at most points of the day in a format designed to be trendy and appealing to children. It includes pasta counters and "zest bars" (serving fruit juice and milkshakes) and is decorated in bright primary colours, playing popular music during the day.