People who are severely obese in middle age are 50% more likely to die early than those of a healthy weight, according to a large study of UK data.
The research shows people with the highest levels of obesity are running a high risk of a range of serious illnesses and premature death, with 12 times the risk of type 2 diabetes, 22 times the risk of sleep apnoea and nearly four times the risk of heart failure compared to those who are of normal weight.
The study of 2.8 million people from anonymised patient records presented at the European Congress on Obesity in Glasgow gives an indication of the extent to which obesity can take a toll on people’s health in the real world – as opposed to clinical trials. Even the least obese, with a body mass index (BMI) of 30 to 35, had twice the risk of high blood pressure, nearly twice the risk of heart failure and nearly six times the risk of sleep apnoea of those with a healthy weight.
Those who were most severely obese had a 50% higher risk of dying prematurely from any cause than those of normal weight. Among the overweight and least obese, there was no increased risk of early death, but experts said this was probably due to the obesity paradox – that people suffering from cardiovascular disease or other obesity-related causes lose weight.
The study was carried out by Novo Nordisk, the Danish pharmaceutical company that manufactures insulin for diabetes. It cannot prove cause and effect, because it is observational and not a classic trial which compares one group against another. However, the company’s Nick Finer, who is also an honorary professor at University College London, said it showed that conditions linked to obesity were “phenomenally high” in the UK.
“It drives home the huge impact that obesity is having on the health of our nation,” he said. “People should know what their BMI is. Those who are overweight or have obesity should be asking their doctors to be assessed for whether they have already developed some of these diseases.”
Researchers used NHS data to look at what happened over 10 years to the health of people in five weight categories, from normal weight (with a BMI or body mass index of 18.5 to 25) through to the most severely obese (with a BMI of 40 to 45). They looked for 12 health outcomes, including death from any cause over the decade.
Those whose health declined most tended to be men and women who already had an underlying condition at the start of the study. The most common of those conditions were high blood pressure (22.8%), asthma (13.1%), osteoarthritis (10.2%), dyslipidaemia – abnormal levels of cholesterol and other fats in the blood – (9.7%) and type 2 diabetes (5.2%). All were more common in the higher obesity groups.
Obesity made the outcomes for these people worse. A history of any cardiovascular trouble, for instance, doubled the risk of unstable angina or heart attack, stroke, and heart failure. Having high blood pressure at the start of the study was strongly associated with developing dyslipidaemia, chronic kidney disease, and type 2 diabetes.
There were increased disease risks at all levels of obesity. People in the group with the lowest severity of obesity, with a BMI of 30 to 35, were more than five times as likely to develop type 2 diabetes and sleep apnoea as those of a normal weight.
“With the number of people living with obesity almost tripling worldwide over the past 30 years (105 million people in 1975 to 650 million in 2016), our findings have serious implications for public health,” said author Christiane Lundegaard Haase from Novo Nordisk. “Body mass index represents an important modifiable risk factor for ameliorating the risk of a wide variety of serious health problems in the general population.”
“This study serves to remind us, once again, how damaging obesity is given its strong associations with a range of conditions beyond diabetes and heart disease,” said Naveed Sattar, professor of metabolic medicine at the University of Glasgow.
“Like most observational BMI studies using routine health data, there are limitations to this work but I suspect some risks are in fact underestimated. The health profession needs to up its game in helping people improve their weight (there are good signs that it is doing so) as it is unlikely that food environment is going to drastically improve anytime soon.”
Dr Katarina Kos, senior lecturer in diabetes and obesity research at the University of Exeter Medical School, said the study confirmed the known link between obesity, disease and premature death.
“Given the health risk of obesity, it is time to move away from considering obesity as a lifestyle choice,” she said. “Instead we all have to take responsibility of our future health. We cannot assume that we get away with it. As this study shows, it may just be a matter of time.”
