Barely a week goes by without startling revelations about obesity levels in this country.

Yesterday, the National Obesity Forum called for more to be done to tackle the rising numbers of so-called “sumo babies”. Experts say the number of larger-than-average newborns has been increasing since the 1960s because of rising numbers of overweight and obese pregnant women.

According to figures released in The Sun, almost a third of the UK’s maternity wards have delivered babies weighing more than 12lb in the last year. The average weight of a newborn is 7lb 4oz for a girl and 7lb 8oz for a boy.

And last week, new NHS guidance urged a “respectful and non-judgmental” approach to the problem of obesity.

Stigmatising obese and overweight people with a “pull yourself together” approach can deter people from seeking help, says the National Institute for Health and Care Excellence (Nice), which has told GPs to identify people who can be referred for weight management programmes such as WeightWatchers in a bid to help them slim down. Providers of weightloss courses would have to demonstrate that participants maintain their weight loss and their programmes are effective at 12 months or beyond.

Nice said Rosemary Conley, Slimming World and WeightWatchers have been shown to be effective at 12 to 18 months and suggested Public Health England could be a national source of information on programmes suitable for commissioning.

The watchdog acknowledged the difficulties of losing weight and maintaining weight loss, saying there was “no magic bullet” to the problem. It said evidence showed that an effective weight loss programme where participants receive support and advice on lifestyle changes can lead to an average three per cent weight loss, which if kept off long term, will have beneficial health effects.

Carol Weir, guidance developer for Nice and head of service for nutrition and dietetics at Leeds Community Healthcare NHS Trust, said: “Obviously, if you need to lose weight, the more weight you lose the better, but even a three per cent loss, kept up long term, is beneficial, that is why we are recommending sensible changes that can be sustained lifelong,” she said.

“Evidence tells us that the elements of an effective programme are sensible changes to diet, an increase in physical activity and changing behaviours such as setting achievable weight loss goals, regular monitoring, a food and physical activity diary, planning ahead, having a buddy, and using a respectful and non-judgmental approach.”

Professor Mike Kelly, director of the centre for public health at Nice, said obesity costs the British economy and the NHS billions of pounds a year, as well as increasing the risk of diabetes, heart disease, and some cancers. Prof Kelly said a total of 42 per cent of men and 32 per cent of women are overweight, with more than a quarter of adults in England now classified as obese – but he acknowledged that losing weight was difficult.

“It’s not something where you can just wake up one morning and say ‘I am going to lose 10llbs’ – it takes resolve and encouragement. One of the things about these programmes is the mutual support from others trying to do the same thing, hugely helpful from a motivational point of view.”

Sam Wheeler, of Shipley, lost 5st on the Slimming World programme, and says she couldn’t have done it without weekly support meetings.

“When you’re overweight you get into a rut; there’s a stigma attached to weight and you feel ashamed. I started comfort eating when my sister died. It’s not an excuse but it was what I turned to. It wasn’t until I joined a slimming club that I looked at why I over-ate. I set out a plan for healthy eating and the meetings really helped – everyone was in the same boat and supported each other.

“Simply telling an overweight person to ‘get a grip and lose weight’ is an unrealistic way of tackling the problem long term.”

Public health minister Jane Ellison said: “We are the first country in Europe to recommend a voluntary scheme giving colour coded nutrition information on the front of food packaging to make it easier for consumers to know what they are buying. Those businesses already signed up to the scheme account for nearly two thirds of all the food that is sold in the UK.

“We are working with industry on reducing calories overall, including from sugar, and many food and soft drink manufacturers and retailers are taking sugar out of their products. The Scientific Advisory Committee on Nutrition is also doing a review of all carbohydrates. Their report, due later this year, will inform our future thinking.”