It is the carrot, not the stick that works best in secondary schools' healthy-eating drives.
That is the message from Gerry Lyons, head of All Saints Secondary in Glasgow, who chaired the city council's strategy group for The Big Eat In - a programme aimed at increasing the number of S1 pupils eating school lunches.
Eight secondaries took part in the pilot scheme this year and a further 11 are expected to join it next session, bringing two-thirds of Glasgow's secondaries into the programme. The aim was to encourage healthy eating habits by removing easy access to junk food in nearby shops and fast-food outlets.
But the programme worked best when pupils were given a positive incentive to stay in school at lunchtime, rather than when staff policed the gates and tried to prevent first-year pupils from going off-site.
The Big Eat In has yet to receive its final evaluation, but interim findings and his school's experience have persuaded Mr Lyons that the key to winning hearts and minds is to provide S1s with a good reason to stay.
The programme was set up in conjunction with Culture and Sport Glasgow - the department hived off from council control to trust status. The plan was for expressive arts and sports specialists from Culture and Sport Glasgow to run activities for S1s at lunchtime. Schools had "impossible expectations" of what Culture and Sport could deliver, he said.
"Schools thought they would be sending in large groups of staff to run massive amounts of activities, but that was never feasible and arose from a misunderstanding of what we should expect from Culture and Sport Glasgow," said Mr Lyons.
But the culture and sports body had delivered invaluable training to others who had then provided lunchtime activities, he said.
In his school, Culture and Sport had trained S4-5 pupils to be play leaders for the S1s in the S1-only area of the playground. It also developed a "chill-out zone" two days a week which had proved very popular; and he had spent pound;3,000 of the school budget on buying recreational equipment for the S1s.
Some teachers had started activity groups, but stopped running them before the preliminary exams when they felt study support sessions for older pupils took priority, he said. And outdoor activities had been difficult to sustain during the severe weather conditions in January.
Preparation was vital, he advised other secondary schools interested in coming on board.
They should engage with their feeder primaries, not only to build up pupils' expectations about activity sessions on offer, but to explain to parents the philosophy behind the programme and establish what lunchtime policies had been operated in P7.
The increase in S1 pupils staying at school for lunch had caused longer queues, he reported. But that had been tackled in part by introducing a pre-ordering service.
Mr Lyons expects some of this year's S1s to choose fast-food outlets for lunch when they enter S2 next year - "because they can", he said.
"Fewer will leave the premises at lunchtime than in previous years because a lot of them enjoy being in school. Pupils like the engagement with staff, and they feel safer - I know the parents like that. Support from parents was unequivocal - they emphasised not just the food but the safety aspect of the scheme."