In its wishlist for the forthcoming Assembly elections, the Royal College of Nursing in Wales has demanded that cooking is put back into the school curriculum.

It has a valid point. A curriculum which teaches children how to design and market a biscuit but not to make one is not fit for purpose. But are they assuming that schools do nothing about health?

Estyn inspection reports are very positive about the standard of personal and social education programmes in secondary schools, which include personal health and diet.

The Assembly government, in its policy document, Appetite for Life, has 41 recommendations to try to tackle the issue of obesity in the young.

One proposal, which has caught the headlines, is banning the sale of confectionery and snacks on school premises. But good headlines do not necessarily equate to good action. The proposals are right to target the issue but there is a danger of the law of unintended consequences coming into play.

Demonising obesity and making some children a target of bullying is one such potential outcome. Another is that the 80 per cent of our pupils who are not obese, and who seem to have got the healthy eating and exercise message, may be deprived of the right to choose because of the poor choices of a minority.

What happens if the student council (now a requirement in all Welsh schools), representing the majority, states that pupils want the chance to buy a bar of chocolate at break time?

Under the Assembly government proposals, the response will have to be “sorry, that is the law”. The subsequent debate on the theory and practice of democracy in Wales will be an interesting one to eavesdrop. Trying to explain to a teenager that heshe cannot have a fruit bar from a vending machine when their friend, who attends college or goes to work, can do so at any time, will not be a rewarding task for teachers.

And do we really want to see the undignified scenes of mothers pushing burgers and chips through school railings in Rotherham replayed in Wales?

At my school, having consulted parents and students, we decided to keep the younger students on site at lunchtime. It required heavy investment in fencing and staffing, and improved facilities, including three food outlets with different types of food and a positive encouragement (rather than compulsion) to eat healthily.

Parents were supportive but a few exercised their right for their child to leave the premises to supposedly go home. With 14 food outlets within walking distance of the school, it did make one suspicious of the motives of some parents who lived four miles away.

Are we heading into a legal minefield as to a school’s authority to “detain” students on site at lunchtime against their will?

All of this took place in a context of an annual deficit of pound;25,000 on the catering service. If the school had not acted, funds would have had to have been diverted from other areas of the school budget.

Healthy food provision does increase costs in terms of ingredients and staff time. If costs rise and revenue from vending and other sales is reduced, who will pay? The school budget in terms of staff posts, or the parents in terms of the cost of school meals?

If the number of students bringing packed lunches increases to avoid higher meal prices, who is expected to monitor the contents?

In reality bans are easy to announce and make good headlines, but are a waste of time if they cannot be effectively policed. And we should remember that forbidden fruit can be attractive to a young adult.

We should also heed the lessons of history such as the fate of the South Sea Islanders, who had never had a common cold until the arrival of strangers on ships. Isolating young adults entirely from the realities of life may not be the best form of education.

Appetite for Life contains many excellent ideas and the Association of School and College Leaders Cymru will support the initiative fully.

However, I hope that the minister, who has sensibly refused to follow the England path of knee-jerk curriculum planning, will show the same wisdom and trust in school leaders in deciding what measures to impose on secondary schools and colleges.

The real challenges for the Assembly government are to tackle the minority of parents who are not fulfilling their duties to their children, and the media industry which persistently targets its advertising campaigns at an impressionable audience.

Gareth Jones is secretary of the Association of School and College Leaders Cymru