Obese men have only a one in 210 chance of attaining a healthy body weight, according to new research that suggests diet and exercise strategies are not effective in combating the obesity epidemic.

While obese women stand a slightly higher one in 124 chance, experts from King’s College London, who conducted the study, said that existing weight loss programmes in the UK were “not working for the vast majority of obese patients”.

The findings are based on the electronic health records of 279,000 people. People who were categorised as severely obese were even less likely to attain healthy weight – with a 1 in 1,290 chance among men and a one in 677 chance among women.

While a significant number of patients were able to lose five per cent of their weight, most regained it after only a few years.

Each year obese men have a one in 12 chance of achieving five per cent weight loss, rising to one in 10 among women. But 53 per cent of people who had achieved this regained the weight within a year, and after five years, only 22 per cent had maintained their weight loss.

The findings, which are published in the American Journal of Public Health, are based on UK patient records dating from 2004 to 2014.

“Once an adult becomes obese, it is very unlikely that they will return to a healthy body weight,” said Dr Alison Fildes, from King’s Division of Health and Social Care Research. “New approaches are urgently needed to deal with this issue. Obesity treatments should focus on preventing overweight and obese patients gaining further weight, while also helping those that do lose weight to keep it off.”

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Patients who had undergone weight loss surgery were excluded from the study, which is part of a wider research project to understand how successful different obesity treatments are on a population-wide level.

The National Institute for Health and Care Excellence (NICE) recommended last year that the NHS should triple the number of weight loss operations it carries out each year, lowering the threshold at which patients can be considered for bariatric surgery. Anyone with a body mass index of 30 or more who has been diagnosed with a weight-related illness can now be considered for surgery.

Many scientists now believe that weight loss is made more difficult for the obese because of biological changes that kick in when someone has gained a certain amount of weight.

Dr Fildes added that the modern Western environment encouraged sedentary lifestyles and the consumption of unhealthy foods. “It’s very difficult to fight against that,” she said.

“The risk with findings like this is that people get despondent and think there is no hope,” she said. “We would say the key message in terms of public health policy is that we need to be focusing more on prevention because it is difficult to lose weight once you are obese.”

Professor Martin Gulliford, senior author of the paper said: “Current strategies to tackle obesity, which mainly focus on cutting calories and boosting physical activity, are failing to help the majority of obese patients to shed weight and maintain that weight loss. The greatest opportunity for stemming the current obesity epidemic is in wider-reaching public health policies to prevent obesity in the population.”