Over two billion people around the world are now affected by weight problems, according to new research published today in The New England Journal of Medicine. At the same time, more people are dying from weight-related health conditions than ever before -- a development the authors are describing as a "growing and disturbing global public health crisis".
It isn't the obesity epidemic any more -- it's now the obesity pandemic.
Such is the conclusion of an alarming new report compiled by researchers from the Institute for Health Metrics and Evaluation (IHME) at the University of Washington. As the team's research reveals, over 30 per cent of all humans are now either overweight or obese, where being overweight is defined as having a body mass index (BMI) between 25 and 29.9, and where obesity is having a BMI above 30 (BMI is the standard measure of quantifying muscle, fat and bone in an individual).
On their own, these results aren't completely surprising; if anything they're a confirmation of what we already knew. But what is surprising is the extent of the associated health consequences. The new research shows that, of the approximately four million deaths attributed to excess body weight in 2015, around 40 per cent happened to people whose BMI fell below the obesity threshold (that is, within the overweight category). This finding runs contrary to previous research which suggested that being overweight (but not obese) was associated with lower mortality rates, implying that being overweight was somehow protective. "[The new finding] makes much more sense given what we know about the physiological ramifications of overweight and obesity," said Christopher Ochner, a researcher at HCA-Physician Services Group who was not involved with the study, in an interview with Gizmodo.
"People who shrug off weight gain do so at their own risk -- risk of cardiovascular disease, diabetes, cancer, and other life-threatening conditions," said study co-author Christopher Murray in a statement. "Those half-serious New Year's resolutions to lose weight should become year-round commitments to lose weight and prevent future weight gain."
For the study, the researchers looked at data collected around the world for over 68.5 million people. The team used data from the 2015 Global Burden of Disease Study, which involved more than 2300 collaborators in 133 countries. The researchers were looking for trends in the prevalence of weight problems among children and adults from 1980 to 2015, while also looking at the associated health risks.
Results show that, globally, there are now 107.7 million children and 603.7 million adults who are now obese. The prevalence of obesity doubled in more than 70 countries since 1980. More adults are obese than children, but the rate of increase is higher among children. In particular, there's been a tripling of obesity in youth and young adults in developing, middle class countries, such as China, Brazil and Indonesia. This is considered a particularly worrisome trend because overweight children are at higher risk for the early onset of diseases such as type 2 diabetes, hypertension and chronic kidney disease.
Amongst the most populous nations, the highest rate of childhood obesity was found in the United States at nearly 13 per cent. Egypt ranked at the top of the list for obese adults at about 35 per cent.
This study "offers a discouraging reminder that the global obesity epidemic is worsening in most parts of the world and that its implications regarding both physical health and economic health remain ominous," noted the authors in an accompanying NEJM editorial.
According to William Dietz, a professor at the Milken Institute School of Public Health at George Washington University (who wasn't involved with the new study), the global reach of obesity has much to do with the westernisation of the global diet. "Indigenous diets are being replaced by diets consisting of highly processed foods and containing excess amounts of salt and added sugar," he told Gizmodo. "Juices and soft drinks are an important contributor to the problem."
To turn these trends around, Ochner says "we need a focus on prevention, particularly in children, and a recognition that obesity truly is a medical disease that cannot treated effectively using behavioural approaches alone".
But while the overall rate of death is on the rise, obese people are living healthier and longer than ever before. The researchers say this is the result of better healthcare and risk management strategies. While that's certainly encouraging news, it also means that overweight and obese people are living longer with associated diseases.
In terms of limitations, the study's estimates assume a global view of mortality -- a one-size-fits-all approach that doesn't account for differences among populations. For example, at any given measure of BMI, Asians have a higher risk of diabetes and hypertension, while African-Americans have a lower risk of cardiovascular disease than other groups. In future, it would be good to see a breakdown of obesity rates and associated diseases by country or ethnic group.
Relatedly, BMI tells us how big we are -- but not how sick we are. "Our behaviours are much more important," Jean-Philippe Chaput, a research scientist at Healthy Active Living and Obesity Research Group, told Gizmodo. "Many lean people have poor health and many obese people have optimal health. Looking at numbers on a scale is not enough and I would never advise an obese person to lose weight if his blood pressure, glucose levels, mental health, etc. are fine."