Is your fridge groaning under the weight of Christmas goodies? Are you looking forward to doing nothing for the next week or so? Then be warned: we are all going to hear a lot more than usual about leading healthy lives and the impact is likely to be particularly felt in our schools.

So alarmed is the Government about official projections that half of adults could be dangerously fat by the mid-century, that it is preparing an action plan, the Healthy Weight Strategy, which is due out for consultation around now.

It is clear that children and schools will be at the heart of the campaign to get us all eating better and exercising more: officials from the Department for Children, Schools and Families are co-ordinating the plans alongside health department colleagues.

Practical cookery, nutrition, parenting classes and more exercise are being called for. But reversing the trend is not going to happen overnight. So will schools find themselves adapting furniture and buildings to accommodate larger children, in the same way that some hospitals are buying reinforced beds and stretchers?

“Not yet,” says Paul Gately, a child obesity expert. “But that might be the situation in 20 years. We’re on that path.”

Professor Gately, the technical director of Carnegie Weight Management at Leeds Metropolitan University, which treats 300 children a year, says schools have done their best to deliver on the Government’s health strategies, with breakfast and after-school clubs, more sport and better meals - without any evidence of beneficial effects on children’s weight.

He believes radical change is necessary for schools to make a significant difference. “One in three children is overweight or obese so that means prevention in schools would have to be pretty significant to counter that. I ask Ed Balls, the Schools Secretary, ‘if every child matters, why not the 4.6 million obese ones?’”

Pupils in England are weighed and measured in schools by health workers at five and 11 and, controversially, from 2008 parents will get letters if their offspring are overweight. Professor Gately approves, but would go further. “It shouldn’t be the role of school nurses to weigh children, it should be teachers. Behaviours are educational and we’ve got to educate children to be more physically active and eat a better diet. This is put in the hands of school nurses because everybody says it’s a health condition, but it’s a social condition.”

He wants schools to work with organisations, such as his own, which help children lose weight. Without intensive and targeted help, he says, it does not happen - and that won’t come cheap.

Professor Gately is sympathetic to schools but says change is necessary - starting with perception. “We’ve become immune to fat children,” he says. “As weight has gradually crept up, so have our perceptions of what is normal. When I have a child who’s 30 stone everyone looks and says: “That child is massive”. If he’s 15 stone, which is still massively obese, people just say he’s a big child.”

Then, everyone should act. “When I talk to school staff, I ask who would be happy to contact the parents of a child failing in maths, or if they were concerned that he might have a heart condition. All hands go up. How many would contact if the child was overweight or obese? Hands go down, and I ask, what is the difference?”

Bullying policies rarely include obesity. “We’ve just got some interesting data from research that overweight and obese children have lower levels of self-esteem than ‘normal’ children. If you separate those who’ve been teased and bullied about their weight from those who haven’t, even those who haven’t have much lower levels of self-esteem.”

He worries that weight problems will disproportionately affect particular children. “We have just finished a four-year study of Year 7s in Leeds. In some schools the proportion of overweight pupils is 20 or even 15 per cent, below the national average. We’ve got two schools, though, where the levels are more than 70 per cent and where it will have a profound impact. The question now is: how serious are we about tackling this?”

Other experts would be content with less dramatic measures. Tam Fry and David Haslam of the National Obesity Forum want to see more physical activity than the Government’s targeted two hours a week - that’s simply not enough, they say, especially since it includes changing time. Dr Haslam adds: “There’s not enough activity in school - it can be scheduled or playground. Children always used to exercise at break time and they need to be prevented from going inside.”

They and others blame a generation of parents denied practical cookery and parenting classes at school and want a long-term strategy in which today’s pupils learn how to be tomorrow’s parents. “There are a lot of children leaving school without any extended family and they don’t know enough about parenting for the future,” says Tam.

In one radical experiment five Scottish authorities are piloting free school meals in an attempt to change eating habits: “The kids go home and say: ‘Can we have something like that, we don’t want pie and chips’,” says Tam.

Kevin Brennan, the children’s minister, agrees that schools will have a role, but says: “I wouldn’t like to give the impression that they can solve the problem on their own. They are a helpful catalyst. When I went to school in the 1970s we had cookery, everybody did it and got a really good introduction.”

Polly Turton of Cabe, a government-funded building watchdog, thinks schools and their surroundings may change - not to accommodate larger pupils, but to build more exercise into the day. “We’ll need to see playgrounds that are as well designed for encouraging play and exercise as possible.

“Organisations are looking at strategies to create safe routes to school, perhaps with parks on the way, so that pupils are more likely to walk and be more active by default. It’s going to take a lot of work and lobbying and leadership by headteachers and planning officers. But we’re realistic optimists.”

Fat facts

- 60 per cent of adult men, 50 per cent of adult women and about 25 per cent of all children under 16 would be obese by 2050, official forecasts suggest. Resulting health costs would be a staggering pound;45 billion.

- National Schoolwear Centres now routinely stock 52-inch-chest blazers, trousers with 42-inch waists and shirts with 17.5-inch collars.

- The Government’s target is to reduce the numbers of obese children to 2,000 levels by 2020.

- Obesity in adults is usually measured by dividing weight by height to get body mass index: over 25 is overweight, over 30 is obese.

For children, see www.weightconcern.com.

Fighting fit

Danny Mason is one of the most popular members of staff at Baverstock School in Birmingham and he may be the shape of things to come.

For Danny is the school’s full-time personal trainer, working in small groups with pupils referred to him by the school nurse because they find it difficult or impossible to cope in timetabled PE sessions.

He worked part-time in Baverstock’s Fit4Life programme for four years before the school found full-time funding for him at Easter.

Ben Lewis, the school’s director of specialism, says:?” For some pupils it’s been about weight loss, we have had children with self-esteem issues, perhaps lacking confidence, some are recovering from injury, some have medical problems such as asthma.

“They do a short-term programme with Danny, usually about six to eight weeks, and then feel a lot more comfortable coming back into their usual groups.

“The aim is to support them and their families about healthy lifestyles as well. The effect on one pupil has been dramatic. He wasn’t enjoying PE at all. In fact, he hated it. Now he’s a member of the local gym and he said it was because of his work with Danny.”

Losing it: weight management programmes for kids and families

The Carnegie International Camp

Britain’s first residential weight loss summer camp for overweight and obese children was developed at Leeds Metropolitan University in 1999.

About 1,500 people have attended, according to the non-profit making organisation, and research showed significantly reduced weight, body mass index and fat levels over a three-year period. Self-esteem also improved.

Campers have an active programme, healthy meals and learn about a healthy lifestyle, with family involvement. Fees range from pound;1,300 for two weeks, to pound;4,030 for eight.

Carnegie has expanded to include non-residential summer camps and 12-week healthy lifestyle programmes.

MEND (Mind, Exercise, Nutrition... Do it!)

This 10-week course of twice-weekly group sessions includes nutritional guidance, behaviour modification and exercise, involving families and children, and has shown significantly improved health outcomes. It runs in 170 areas and is free to families thanks to funding from the Big Lottery Fund, Sainsbury’s, Sport England and local health authorities.