image copyrightJoanne Crawford / BBC

Specialist health professionals say it is time for obesity to be regarded as an illness caused by genetics, biology and how we live today.

New research adds to growing scientific opinion that "healthy obesity" does not exist. The findings show those who are significantly overweight have a 66% higher risk of developing chronic kidney disease, compared with those of a normal weight.

Many people with obesity say not only do they have to live with prejudice and stigma, but they struggle to find treatment.

Sarah has lived with obesity her entire adult life. The 39-year-old mum has a Body Mass Index, or BMI, of over 40, which means she is medically classified as having "severe obesity" and is overweight enough for her health to be at risk.

"People think you're unintelligent, that you're lazy, that you eat too much, that you've done this to yourself. That it's a choice," she says. "I just want to scream and say none of those things are right."

Sarah has spent most of her life trying to control her weight through diet and exercise, and says her obesity is something that she thinks about every day.

Growing up in Jersey, in the Channel Islands, Sarah was a "normal-sized" girl, until the end of primary school when she began to develop before some of the other girls in her class. By the time she went to an all-girls secondary school, the changes of puberty meant she started to feel different from many of her friends.

image captionSarah as a 12-year-old

In her early teens, she was aware her mum had regularly struggled with her own weight and had tried lots of diets, so as Sarah's weight increased, she did the same.

At 16, she decided to go on an 800-calorie-a-day milkshake diet. Over the summer before starting her A-levels, she says she dropped from a size 14 to a size 10. At the time, it made her feel "brilliant". But, in hindsight, she realises this was the start of years and years of yo-yo dieting.

Sarah was around a size 12 when she started university. But when she graduated three years later, she had grown to a size 20. The student lifestyle – drinking and eating late – meant she couldn't keep on top of her weight.

image copyrightJoanne Crawford / BBC

But unlike when she was 16, this time diets weren't working. It was the start of a struggle to regulate her weight.

Scientists have found that people's genetic background means their weight changes differently, even if they eat the same amount of calories.

Obesity genes

After university, Sarah started working in the pharmaceutical industry. She was performing well as a sales person, selling a diabetes drug. But she was taken aback after her boss told her that when he first met her he remembers thinking, "You better be a bloody good sales rep, looking the way you do, trying to sell a diabetes drug".

Sarah now says it should be against the law to make comments about body shape and size.

By the time she was 30, Sarah had severe obesity and was desperate to do something about it for the sake of her mental and physical health. She embarked on a year-long project with a personal trainer and completed an Olympic-class triathlon – swimming 1.5km, cycling 40km and running 10km. She also lost eight-and-a-half stone (55kg).

Around this time, she had some tests which looked at her genetic make-up. The results found two important things:

  • she possesses a variant of the FTO gene, which is associated with weight gain and increases the risk of obesity
  • she has a mutation of the MC4 receptor which causes obesity

Shaw Somers, a consultant surgeon who specialises in weight-loss operations, has been treating people with severe obesity for many years. He says people like Sarah, who have an inherited set of certain genes, are much more likely to develop obesity compared with those who don't.

But obesity is not just about genetics, he says. It is also about psychology, inequalities and the food environment we all live with.

Historically, he says, people with these genetics would have done well in a famine, but with today's plentiful, high-calorie food they will put on weight "without strong determination and support".

Information and support

  • Information about obesity from the NHS
  • Bullying
  • Eating disorders
  • Mental health and self-harm:

Dr Denise Ratcliffe, a clinical psychologist who supports patients through bariatric surgery, says people's past experiences can come into play. She says that many of the people she sees, have experienced trauma, abuse or neglect, for example, which leads to a dysfunctional relationship with food.

"I think there's something about the psychological experiences people have, and the relationships that they start to form with foods, that becomes almost like a perfect storm."

Both the genetic and psychological components of obesity can be amplified when there is easy access to fatty, sugar-laden foods, which are available cheaply and conveniently.

Sarah's friend Jed has lived on an estate in Hull all his life. He lives with obesity, and thinks areas like his can have a big effect on the health of those living there. Across the road from his house, he remembers the parade of shops once having a greengrocer's and a butcher's – now eight of the 20 shops are fast-food outlets.

"We've got a chicken place, we've got a burger place, we have got a fish shop, we've got a kebab shop, another kebab place, another chip shop, and a Chinese," he says.

Jed says that he recently signed a petition to try to prevent another takeaway from opening.

"If you look at any area in your city, which is at a low level of socio-economic standing, I guarantee there's going to be more takeaways. We don't need to kick areas like this down. We need to lift them up."

After training for the triathlon and losing eight-and-a-half stone, Sarah continued to train regularly and eat well. But she noticed that gradually she started to become heavier. Whatever she did, it made no difference.

Dr Abd Tahrani, a senior lecturer in obesity medicine at the University of Birmingham, says there are a lot of people who are "biologically pre-designed to conserve energy", which is stored as fat. He explains that signals from the hypothalamus – the part of the brain that controls appetite – bombard the person with feelings of hunger and a desire to eat, that are almost impossible to fight.

So even if the person successfully loses several stone by dieting, their body remembers its baseline weight and strives to return to it.

Studies from GP records in the UK showed that the annual chance of achieving normal weight in people with morbid obesity is one-in-700 to one-in-1,000.

As Sarah started to research obesity, she realised that after a lifetime of blaming herself, she understood that it was actually her body "working against her".

Obesity is an illness

New research from a team made up of specialists from the University of Birmingham, the University Hospitals of Birmingham, and Warwick Medical School, has found that people living with obesity have a 66% higher risk of developing chronic kidney disease than those with normal body weight. This is the case, even if they have no underlying health conditions, such as diabetes or high blood pressure.

The work has just been published in the American Journal of Kidney Disease and involved studying 4.5 million patient records from GPs in the UK over 20 years.

This adds to a growing body of scientific research which has found that "healthy obesity does not exist", says Professor Indranil Dasgupta, consultant nephrologist at the University Hospitals Birmingham NHS Trust, and senior author of the research paper. Previous studies from the same team found those living with obesity without any other health conditions also have a higher risk of cardiovascular disease and stroke.

Obesity in the UK

  • England: 28% of adults are obese (Health Survey for England 2019)
  • Wales: 25% of adults are obese (National Survey for Wales 2019-20)
  • Scotland: 29% of adults are obese (Scottish Health Survey 2019)
  • Northern Ireland: 25% of adults are obese (Health Survey Northern Ireland 2018-19)

Many professionals with an understanding of obesity believe there needs to be a huge shift within the medical profession, and society as a whole, in how the condition is viewed.

"Public perception hasn't quite understood that it's a real illness," says bariatric weight loss surgeon Shaw Somers. "With each passing year that we fail to get on board with managing the obesity epidemic, it gets exponentially worse. Unless we start to take this issue seriously, it will totally undermine the NHS' ability to cope in the near future."

There also needs to be a big change in the understanding of treatment, according to Mr Somers. Too many weight management programmes for those living with obesity begin with "moving more and eating less", which in reality is a prevention for obesity, not a cure.

"The number of people I've encountered in my 30-year career who've been able to go from morbid obesity, to normal weight, and sustain it by dieting alone – well I don't think I've ever met one. It's so hard to do."

Evidence suggests that people like Sarah, whose bodies are hard-wired to put on and retain fat, may put in all the work, and still not get the result they badly want. This can be a huge mental strain.

"I went through some really dark times, because I felt like a failure," says Sarah.

Psychologist Dr Denise Ratcliffe says that many people accept the narrative that they are to blame for their obesity. That, and the harsh judgement of society, can lead to a situation where mental anguish and physical weight-gain feed off each other.

"Obesity is a cause of mental health problems. So if you've got mental health problems, you're more likely to have obesity. But if you're obese, that also creates mental health difficulties."

What is the treatment?

The NHS has a four-tier recommended treatment process for obesity. Tier 1 promotes healthy eating and active lifestyles, while Tier 2 is usually funding for slimming clubs. Both these tiers are normally paid for by the local authority. Tier 3 treatment is offered by the NHS. Health professionals can give medication, help with lifestyle behaviours and preparation for Tier 4 treatment, where patients are supported through bariatric weight-loss surgery.

But, as Sarah found when she previously sought help from her GP, to be told there was no provision for her, treatment is not available in all areas of the UK.

"There is a postcode-related issue here where some people will not have services available. Ultimately it means there's no support for them," says Stuart Flint, a director of Obesity UK, and associate professor in psychology at the University of Leeds.

Sarah has decided she doesn't want bariatric surgery. She feels that if she were to go ahead with the major operation only to find she regained some weight in the future, she would find it too difficult to deal with mentally.

The NHS says bariatric surgery can achieve dramatic weight loss. Although patients need to make permanent lifestyle changes after surgery to avoid putting weight back on, it can also lead to hormone changes that can reduce appetite. And the evidence for cost-effectiveness and health improvement are clear, from many studies around the world.

Around 6,000 people each year in England go ahead with an operation to help reduce their weight and improve their health dramatically. Compared with other European countries, England has one the highest rates of adult obesity and one of the lowest rates of spending per capita on this kind of surgery.

The most common types are:

  • gastric band – placed around the stomach, making you feel fuller sooner
  • gastric bypass – top part of your stomach is joined to the small intestine, so you feel fuller sooner, absorb fewer calories from food and your metabolism improves
  • sleeve gastrectomy – part of stomach removed so you cannot eat as much, and feel fuller sooner. Metabolism improves

The government says it has launched a strategy to tackle obesity. It plans to increase weight management services so that more people get NHS support to lose weight. It is also going to legislate to end the promotion of foods high in fat, sugar and salt.

NHS England says it is focusing on support for those who live with obesity and have other health conditions, such as type 2 diabetes and high blood pressure.

Shaw Somers carries out weight loss operations at Portsmouth Hospitals NHS Trust, and privately in London for patients without Tier 4 services in their area, and who have had to fund the operation themselves.

"Many people who struggle with severe obesity have a number of underlying illnesses, which are all harder to treat because of their obesity," he says. "They get stuck in a vicious cycle, where their illness makes them more likely to put on weight and the weight makes their illness worse."

One of his most recent operations was on a patient with chronic kidney disease. He explains that the surgery wasn't just to improve his life, it was to save the man's life.

At the obesity clinic in Queen Alexandra Hospital in Portsmouth, Mr Somers is joined by other specialists – a dietician, a psychologist, nurses, and an anaesthetist. They offer extensive pre- and post-operative care. All of his patients have been through Tier 3 of NHS treatment, as well as years of failed dieting, mental health anguish or illnesses like diabetes and high blood pressure that many obese patients suffer.

For Sarah, her hope now lies with medical science. Research into drugs that suppress the appetite, like Saxenda and Semaglutide, are making strides forward, according to Dr Abd Tahrani.

There's also research into a drug for those, like Sarah, who have a mutation of the MC4 receptor.

Dr Tahrani says that Semaglutide was approved in the US very recently, and could lead to 15-to-17% weight loss. In the future, he expects to see drugs that could result in 20-to-25% weight loss, which is the same outcome as bariatric surgery.

One in four adults in the UK live with obesity, and the condition can touch almost every area of their lives.

The Department of Health and Social Care described it as "one of the most significant challenges we face today".

It said: "Losing weight is not easy and our world-leading obesity strategy lays out extensive action to empower people to make more informed decisions and achieve a healthier weight."

Sarah is concentrating on staying as healthy as she can, and is determined to make the best of the life she has. She is a successful professional living in a beautiful Yorkshire village. The single mum says her self-confidence is high in all areas – apart from her weight.

Despite what she now knows about obesity, Sarah still wants to be slimmer. She simply wants to fit in, and not be judged.

Being big means thinking about what might go wrong. Even a catch-up with a friend in a pub garden brings anxiety. "What are the chairs going to be like? Are there going to be these rickety chairs that I could sit on and it could collapse?"

But for some people living with obesity, Sarah's admission of being unhappy with her weight is at odds with their argument that it is time to reject the stigma – and the shame – and to live happily as they are. It's called being "body positive". Sarah respects it, but it is not for her.

"I do look at some of the body positive community and kind of envy their self-love. But that's only a small community and the big community of the world feels very differently."

Given that Sarah's weight problems are mainly down to genetics, she does not know how that will impact her two-year-old daughter Emily.

After her own struggle with obesity, Sarah is hoping for something better for her daughter.

"I want her to just know that everyone comes in different shapes and sizes, we have different hair colour, we have different heights, it doesn't matter what she looks like, I just want it to be her. And that's what I'm really passionate about getting that message across to her."

Sarah is setting up a charity to support those with obesity who feel misunderstood and stigmatised. She says the aim is to be a voice for a community that is seldom listened to.

For many scientists and doctors who have developed a deep understanding of obesity, the condition is a complex illness driven by a combination of factors. To blame someone for suffering with that illness flies in the face of the scientific evidence, they say.

"If blame worked," says Dr Abd Tahrani, "we would have a very thin society by now. Everybody who has obesity has been blamed an endless amount of times, either by their doctors, by their neighbours or their family, or wider society. It's not working, please stop it."