Mild Obesity May Not Be So Bad

Doctors and media stories have been telling us for years that fat kills us. But a new study in the Journal of the American Medical Association challenges that belief. In a review of nearly 100 studies, the paper’s authors found not only that being overweight or slightly obese does not make a person more prone to death, but that those people are slightly less likely to die than their fit counterparts. The New York Times reports:

Experts not involved in the research said it suggested that overweight people need not panic unless they have other indicators of poor health and that depending on where fat is in the body, it might be protective or even nutritional for older or sicker people. But over all, piling on pounds and becoming more than slightly obese remains dangerous.

The study did show that the two highest obesity categories (Body Mass Index of 35 or above) remain high risk. A little butt or arm flab, on the other hand, should not be cause for distress, the authors said. Extra fat can also be accompanied by healthy extra muscle, to a point. Reuters explains these distinctions:

Also, there are concerns that body mass index (BMI) – a measurement of weight in relation to height – is not an accurate measure of someone’s health risks.

For example, Heymsfield said a soldier may be considered overweight but still be healthy, because he or she has more muscle mass.

BMI doesn’t differentiate between muscle and fat, so the fittest, most ripped athlete’s BMI would likely indicate that they are overweight, when in fact that extra size is just muscle. The logical extension of that train of thought, Slate writes, goes like this: ”So instead of focusing on BMI, we should measure your waist-to-hip ratio, body-fat percentage, blood pressure, blood lipids, glucose, and cardio-respiratory fitness.”

These nuances have some epidemiologists are calling the study’s results into question. In Slate, one researcher pointed out that the death statistic gave overweight people just a 6 percent less likely chance of dying than normal weight people, which could be a fluke of the sample size the study authors used. Critics argued that emaciated cancer patients, for example, may have been included in the skinny people’s life rate calculations, depressing the lifespan figure of the healthy members of the normal-weight cohort. And some studies included in the new publication only tracked participants for 5 years, meaning anyone who made it to that point counted as a survivor, regardless of how healthy they were.

Another criticism of the study, according to Slate, is that mild obesity may be a gateway condition for more severe weight problems. For people on the edge, just adding 10 to 20 extra pounds over a few years can make all the difference between a healthy and dangerous condition.

And, as the Times writes, death is not everything. There’s a whole host of health issues to take into account when figuring out how healthy a person is and how health may correlate with weight. Even if being overweight turns out not to increase a person’s chance of dying, it does increase his chance of having diabetes, high cholesterol and other conditions associated with extra pounds.

More from Smithsonian.com:

The Culture of Obesity
Taking Childhood Obesity to Task

Rachel Nuwer | | READ MORE

Rachel Nuwer is a freelance science writer based in Brooklyn.