Fat and healthy is a myth, study concludes

12/3/2013

Your body mass index says you’re obese, but you don’t have “pre-diabetes” — a mix of factors such as hypertension, high cholesterol and high glucose levels that indicates you’re on the road to metabolic illness. And you’re thinking you’ve beaten the odds, right?

Wait 10 years, a new study says. Odds are, you’ll be proven wrong.

New research finds that even when a person is “metabolically healthy,” being obese raises his or her risk for cardiovascular disease and premature death. It just takes a study that tracks subjects for 10 years or more to pick it up, says the study, published this week in the Annals of Internal Medicine.

The meta-analysis — a study that aggregates the findings of many well-designed studies in an effort to distill larger truths — appears to dash hopes that for some, obesity can be a perfectly healthy state. In recent years, a welter of research has suggested that the illnesses long linked to obesity — cardiovascular disease, Type 2 diabetes and certain cancers — might stem not from obesity itself but from metabolic dysfunction, a condition more common in the obese but by no means universal among those with BMIs over 30.

Those findings had fueled resistance to the nationwide assault on obesity from those who argued they were “fat but fit.”

The latest study does less damage to the growing suspicion that it’s OK to be overweight — with a body mass index between 25 and 30 — if you’re metabolically healthy. On average, cardiovascular disease and death from any cause was not higher among the overweight-but-metabolically-healthy than it was for those of normal weight who were metabolically healthy.

But even those findings left the question open: There was a trend in that direction. But it was not so robust that the researchers could be confident it wasn’t a statistical fluke.

In the end, that trend may be the most significant finding of all. When researchers used BMI to line up all of the 61,386 subjects who participated in the eight studies they pooled, they found that, as BMI rose, so did blood pressure, waist circumference and insulin resistance. As BMI increased, levels of HDL cholesterol, thought to protect against heart attack and stroke, decreased. Though overweight and obese subjects may not yet have reached the points that define metabolic illness, they appeared to be on that road as their weight rose.

“Increased BMI is not a benign condition, even in the absence of metabolic abnormalities,” the authors said in study released Monday.

The newest study does not give “normal weight” people a pass if they are metabolically unhealthy. In this aggregation of subjects from many different studies, the authors found that this group is just as likely as those who are obese and metabolically unhealthy to have a stroke or heart attack or die of any cause — a surprise, since it has long been assumed that the combination of obesity and metabolic dysfunction confers the greatest risk.