Back in the 1980s, the term "metabolically healthy obesity" began popping up in medical circles. It referred to obese people who displayed no other signs of related health complications, like hypertension or diabetes. The phrase evolved into the societally popular term "healthy obesity."
But a researcher from the U.K.'s Loughborough University has called for people to stop using the term. William Johnson calls the idea of healthy obesity "crude and problematic" in a commentary published in the April 11, 2018, issue of the journal Annals of Human Biology. He writes that the concept of zero complications despite obese status is attractive, especially to those people with a body mass index (BMI) of 30 or greater, who'd rather not think of themselves as unhealthy. Johnson authored the commentary and holds a doctorate in human biology and epidemiology.
However, Johnson points out that many studies have declared such people to be rare and more likely to eventually become unhealthy compared with non-obese people. Even without current health problems, healthy obese people are still at a higher risk of developing diseases like Type 2 diabetes and chronic kidney disease, not to mention having a higher mortality rate when compared with others of normal weight.
This is unfortunate news for people who look up to athletes who appear overweight but who likely engage in far more exercise, boast more muscle and eat more nutritiously than the average Joe. In fact, current BMI measurements are calculated using only use height and weight. So, the person who has more muscle mass but weighs the same as another person with more fat actually would sport the same BMI. As a result, a clear picture of comparative health is lacking.
"As one might expect, individuals who are obese yet healthy are more likely to be younger, of European ancestry, lead a healthier lifestyle in terms of physical activity and diet, etc., have less central and visceral adiposity [body fat stored within the abdominal cavity] and be of higher socio-economic position than obese individuals who have already developed complications," Johnson explains in the paper.
He notes that the opposite is true when compared with a healthy group of normal weight participants. That is, the healthy but obese group is more likely to be older, of non-European ancestry and more prone to a less healthy lifestyle.
Here's Johnson again:
Johnson isn't the first scholar to call for the idea of healthy obesity to be retired. He's interested less in research that determines whether healthy obesity exists and more interested in rerouting research dollars to figure out why two people with similar BMIs can wind up with such different outcomes, with one dying of disease and the other completely fine.
"It is undeniable that obesity is bad for health, but there are clearly differences between individuals in the extent to which it is bad," he says in the accompanying press release. "While the concept of healthy obesity is crude and problematic and may best be laid to rest, there is great opportunity for human biological investigation of the levels, causes, and consequences of heterogeneity in health among people with the same BMI."