These four social media influencers were swept up by a movement that claims obesity is perfectly healthy... The tragic truth is they have all died under the age of 45

The final videos posted to Brittany Sauer's TikTok page make for upsetting viewing. Speaking tearfully to the camera, the 31-stone social media star, who often posted defiantly 'body-positive' content about how 'hot' she felt in certain outfits, admitted with shocking candour that she had 'ruined her life' with food and binge eating.

And it had left her, aged just 28, full of regrets.

Brittany had been a virtual prisoner in her own home for two years, dealing with type 2 diabetes and repeated bouts of the skin infection cellulitis which had caused a growth in her pelvis weighing more than two stone. She had even been forced to ask someone else to cut her toenails, as it left her 'too breathless'.

Yet she hoped, desperately, that it wasn't too late to save herself. 'I'm scared I'm going to end up in a bad place that my body can't recover from,' she said to her half-a-million TikTok followers. 'I want you to know it's not worth it – food isn't worth your life.'

Within a week of posting the film last December, Brittany was dead.

Her death turns a spotlight on the controversial body positivity and 'fat acceptance' movements that have seduced Brittany and millions of vulnerable young people like her.

The past decade has seen extraordinary momentum building around a central argument that being obese doesn't have to mean unhealthy. In other words, you can be fat and fit.

Branded Health At Every Size, or HAES, the philosophy has, at its heart, laudable goals. It aims to counter the multi-billion-dollar diet industry – which has a poor record when it comes to long-term, sustainable weight loss – and act as an antidote to the stigma encountered by people struggling with their weight.

The idea is that, rather than shame overweight people and force them to diet, they should be encouraged to embrace their bodies, find exercises they enjoy and eat more nutritionally. But some say those philosophies have been taken to extremes, particularly on social media, by celebrating morbid obesity while ignoring its serious health dangers.

The US edition of Cosmopolitan magazine was criticised for running covers featuring plus-size women in yoga poses under the headline: 'This is healthy.' As part of a drive to challenge beauty stereotypes, it also featured US plus-size model Tess Holliday – who at 5ft 3in and 300lb has a BMI of 53, more than double the healthy range – a decision condemned 'as dangerous and misguided'.

Self-styled 'fat activists', meanwhile, not only promote larger bodies as healthy but reject decades of science which prove the dangers of excess body fat, encouraging devotees to ignore doctors who recommend they lose weight.

Some dieticians backing the belief even oppose weight-loss jabs such as Wegovy (also known as Ozempic) and bariatric surgery because they 'continue to encourage weight loss as an important part of health'.

One organisation, HAES UK, described weight-loss surgery as 'mutilating body parts' and 'not compatible with loving your body as it is'. And those who criticise it are labelled 'fat-phobic' or 'anti-woke'.

Little wonder that experts have described the movement as a 'cult'. Some say this so-called 'body positive' approach is also putting vulnerable young people at risk by failing to point out the unpalatable scientific truth: that obesity dramatically increases the risk of a wide range of chronic and life-limiting diseases.

In some cases, they say, it could prove attractive to those with binge eating disorders, like US-born Brittany. After all, she is not the only one to lose her life.

Another TikTok star, @Wafffler69, died of a 'presumed heart attack', according to his brother, aged just 33 in January.

Real name Taylor LeJeune, he did not flaunt his weight but amassed 1.9 million followers by posting videos reviewing bizarre food, including reindeer meat and tinned ham from the 1960s. His last video, posted the day before he died, showed him eating a giant fruit loop in milk.

Jamie Lopez, who starred in US reality TV show Super Sized Salon, died from heart complications aged 37 last December. The show centred around obese women getting beauty treatments and featured the catchphrase: 'Go big or go home.'

She had described being discriminated against for being a plus-size make-up artist, and wanted women like her to feel 'confident and sexy'.

But then Jamie decided to overhaul her health, eventually losing almost 29st (180kg) – half her body weight – before her death.

A well-known activist, professor of 'fat studies' Dr Cat Pausé, who questioned the links between weight and health, lost her life aged 42. Based at Massey University in New Zealand, she also presented a 'fat positive' radio show.

She had said: 'The science isn't quite as clear cut as we'd like to believe and there's not really quite a consensus yet about the relationship between weight and health.

'Obese people, and even morbidly obese people, have just as good health or better health than someone in the normal weight range.' She died in March 2022 from causes which have not been made public.

Obesity researcher Sarah Le Brocq, founder of charity All About Obesity, says that ignoring the health implications of excess fat is delusional.

'People are always going to be different shapes and sizes,' she says. 'That's OK, and we need to be more accepting of that, but you must be mindful of the health implications.

What we know is the more body fat you have, the more likely it is your body will be in an inflamed state. This means you might become insulin resistant and develop diabetes or end up with heart problems.

'Not everyone will, but the more fat you have the more likely it is.'

She adds: 'What we can't do is be delusional about that. If you have a high BMI and you're not eating well, moving much or looking after yourself, it's only a matter of time before that becomes a problem for your health and you start getting aching knees, high blood pressure or sleep apnoea – and that's just the start.'

Ms Le Brocq says her encounters with activists have been 'quite cultish – everyone seems to think and speak the same way, as if they've got a handbook to recite from', adding. 'There's this idea that if you're big you should stay that way, whatever the cost.'

For obesity specialist Professor Naveed Sattar, from the University of Glasgow, the science around health and obesity is irrefutable.

'Ample evidence shows obesity can promote or accelerate over 200 diseases, such as diabetes, strokes, many cancers, diseases that impact movement such as arthritis, and mental health,' he says.

'Higher waist girth is a major reason for many people living with multiple chronic conditions, leading to suffering and health costs.' And for those who say losing weight is not necessary to improve health, he adds: 'Considerable evidence now shows intentional weight loss – via lifestyle or drugs – can help lower the risk of many chronic conditions and even reverse some, such as diabetes.'

Of course, these issues do raise some important points.

Far too many people do not like how they look, and, for many people diets do not work in the longer term. And repeatedly failing to lose weight can take its toll on mental health. For some, using social media to post pictures of themselves fat, happy and eating what they want is a way to love themselves and their bodies.

Dr Asher Larmie, a GP based in Hertfordshire and one of the UK's more public proponents of HAES, believes doctors should not recommend weight loss.

Posting to his 14,000 followers on Instagram as @thefatdoctor, he uses slogans such as 'fat and thriving' and 'you do not need to lose weight to improve your health'. However, Dr Larmie does concede that 'people who are fat are more likely to have certain conditions', although he says the evidence does not prove excess fat is the cause.

He explains: 'What is more important in driving illness is chronic stress, the impact of repeated dieting, and weight stigma and discrimination which means fat people receive far poorer care.

'The deaths of all of these people is heartbreaking and tragic. Some are deeply sad and involve binge eating disorders, which shouldn't be confused with fat acceptance. But they in no way prove that you can't be obese and healthy.'

Dr Larmie's approach is not to mention weight or diets at all, and instead find out what might improve an individual's overall wellbeing.

'I find what activity makes them happy and ask them to incorporate more of it in their daily lives, whether that's walking on the beach, gardening or cleaning the house. If they enjoy it, it's sustainable and will keep them moving in the longer term. I'll look at someone's daily diet and work out ways of eating better, but without restrictions.

'The result means people are happier and at a stable weight that's right for their bodies – they might, in some cases, lose weight. Just releasing people from that cycle of stress and anxiety over their weight can make them healthier overall.'

At one point, some MPs on the Women and Equalities Committee called for medics to adopt the HAES approach to avoid people being 'shamed' for their BMI.

But is it all starting to crumble? The organisation HAES UK appears to have been disbanded, and individuals have posted on social media about rejecting the movement as a result of the spate of deaths.

One wrote that 'body positivity kept me fat and complacent' and 'enabled me to not make good decisions'. Another added: 'I feel guilty for being a part of this movement. Health is real, organs failing is real, diabetes is real. It's not fat-phobic to care about your health.'

Luci Daniels, former chairman of the British Dietetic Association, the professional association for UK dieticians, says: 'HAES and fat acceptance started off with the best of intentions, but it has gone too far. Most people with excess weight would be healthier with less of it. We've been persuaded to accept that big is OK and people who are obese must learn to love themselves. But I've never met an obese person who didn't want to be a more regular size.'

She concludes: 'If you are overweight, don't give up on healthy eating and healthier lifestyle choices. Yes, that will be harder than simply buying into the myth you can be obese and healthy, but it'll be far more worthwhile health-wise.'