Lock-in at lunch holds the key to leaner Scotland

But not at St Mungo's High in Falkirk. There, most pupils are subjected to an English-style lunchtime "lock-in" which, according to staff, delivers huge benefits in terms of healthy eating.

Children in the first four years at St Mungo's are banned from leaving the school grounds at lunchtime, chips are served just once a week, and pupils are allowed just one biscuit a day. They are also banned from bringing in fizzy drinks, cakes or sweets from home.

The policy on enforcing lunchtime "lock-ins" at schools to prevent youngsters from gorging on junk food has been backed by Health Minister Shona Robison as well as celebrity chef Jamie Oliver. Scotland on Sunday also recommended the introduction of break-time curfews in its pioneering national manifesto issued before the Scottish election in May.

Most parents at St Mungo's appear happy with the arrangements. Staff claim that as well as helping to reduce obesity rates, the policies have improved pupil behaviour.

Perhaps most surprising of all, there are few open grumbles from the pupils themselves. They say they enjoy their school dinners and are not particularly interested in trekking to the chip shop or bingeing on cakes.

Lorraine Bertolini, the school's health commissioner, said she believed other schools should follow her example.

To make school lunches more enticing, staff introduced a raft of measures to ensure pupils enjoyed healthy meals in a relaxing environment.

Bertolini, who is also a pupil support teacher, said: "We feed 1,100 pupils within 45 minutes. But instead of them being herded in and out it is more of a restaurant atmosphere. The sixth years supervise it, control the queuing system and make sure the place is tidy. We encourage the children to stay there.

"S1-S4 can't go out at lunchtime but most of the S5 and S6 stay as well. They have the choice to walk 10 minutes into town for chips but they don't go.

"This was [originally] done on safety grounds because the children come from all over the area and it is to keep them in school. They accept it."

Parents are asked not to send their children into school with sweets, cakes or fizzy drinks. Chips are only served once a week, and vending machines sell only water or fruit juice. Pupils are only allowed one cake or biscuit each a day. The dining hall has a TV playing music videos and pupils queuing in the foyer also have a TV to watch.

The school has lunchtime and after-school fitness clubs including cycling, basketball, dodgeball, dance, football and rugby and a gym with weights. Bertolini added: "The pupils are definitely benefiting from it. Removing juice and high- coloured food has improved their behaviour. We don't have a lot of overweight children in our school.

"Lots of schools near us have said they would like to do this, starting at morning break and extending it. This can definitely be done in other schools in Scotland if you get the backing of parents. I think our model is something other schools should look at."

Fifth-year pupil Rebecca Sweeney said she enjoyed school meals so much she was happy to stay in school at lunchtime.

The 15-year-old said: "You can get sandwiches or a panini at school and the prices are much cheaper than going to the shops. I didn't feel deprived by not being allowed out of school until fifth year, it makes it a much bigger deal when you are allowed to go."

Earlier this month, celebrity chef Jamie Oliver, who has campaigned to improve the diet of schoolchildren, gave his backing to closing schoolgates at break times.

He said: "Keeping children on school premises at lunchtimes is one possible solution.It is also important to make sure kids are offered a choice of good food in schools."

The closed-gates policy is already widely enforced in schools south of the Border.

Healthy profits in not so healthy food

IF YOU like betting, bronzed skin and 'bad' food, a half-mile stretch of Duke Street in Glasgow's East End seems like paradise on Earth.

The row of shops is home to no fewer than three tanning salons within a 300-metre stretch, two of them in the same block.

The immediate vicinity also contains seven pubs, four off-licences, three kebab shops, a fish and chip shop, one Indian takeaway, six Chinese takeaways, and a single health food shop.

The reason is simple: money. Selling fish and chips, for example, can be a very profitable business.

Sales figures published on business-for-sale listings show that a chip shop with a 130,000 turnover can make a profit of about 100,000 a year.

However, the same data show that a typical health food shop would need a turnover of at least 200,000 to generate the same kind of profit for its operators.