An obese guy, supposedly. Photo credit: Stephen Dunn/Getty

Two professors and the CEO of a weight-loss company published an op-ed in USA Today—based on their recently published research letter—arguing that the vast majority of baseball players are too fat, and that they “owe it to themselves and to the children who look up to them as role models” to get in shape. It is a load of horseshit, and everybody involved—the authors, the journal that published the research letter, and USA Today—should be ashamed of themselves.


The op-ed makes two main points. The first is that in the last 25 years there has been a drastic change in the body composition of baseball players—70 percent of today’s players are overweight and 10 percent are obese, according to the authors—and the second is that, for the sake of both their own health and that of the greater public to which they are role models, baseball players have a duty to lose weight.

The first point is scientific hogwash; the second is disingenuous concern-trolling.


The authors gathered highly inaccurate self-reported height and weight data for baseball players going back to 1871, and used that to calculate players’ body mass index (BMI). Based solely on this data, “players debuting in the current decade were significantly more likely to be overweight or obese than at any time in history.”

This finding is only true inasmuch as it is backwards. BMI classifies people as normal weight, overweight, and obese, using only the ratio of their height to their weight. When you run muscular professional athletes through the formula, it declares them to be overweight or obese because those are the only categories of heavy bodies BMI recognizes. There’s a serious problem here, but it’s not that ballplayers are fat—it’s that these researchers can’t tell that ballplayers aren’t fat.

What the authors only barely mention, in passing, is that medical professionals overwhelmingly agree that BMI tells you very little about whether someone is healthy or not. About the only real value of BMI is as an easy-to-use screening tool to identify people who may be obese. Because it simply uses weight—which is made up of fat, but also muscle, bones, tissue, and fluids—it isn’t a useful measure of anything for people who are normal or overweight. As our sister site Lifehacker shows visually, people with the exact same BMI can have radically different body compositions, and thus have radically different health statuses.

FiveThirtyEight has a good survey of some of the literature refuting BMI, in which a Mayo Clinic doctor tells them “when we have a measurement that doesn’t really differentiate those who have excess fat, it’s useless.” There is the Nature study which found that using BMI as a measure of health misclassifies almost 75 million adult Americans, and the Annals of Internal Medicine study that found excess belly fat is a far superior indicator of mortality risk than BMI. There are also many researchers who think a focus on fat, no matter the measure, as a measure of health is misleading.



Worse yet, it is widely known that BMI is specifically terrible at classifying athletes. As the CDC notes, “muscular individuals, or highly-trained athletes, may have a high BMI because of increased muscle mass,” not because they actually have excess fat. NPR helpfully demonstrated earlier this year that, according to BMI, every member of the Denver Broncos was overweight or obese. Some of the lineman may actually be obese—albeit extremely athletic and healthy, calling into question the usefulness of the term—but not a single running back, wide receiver, corner back, or safety, had a normal weight?

From its thoroughly unsound methods, the op-ed then leaps to even worse explanations for the phenomenon it purportedly describes. The researchers offer two hypotheses for why ballplayers are fatter than before: It might be due to steroid use, or due to “advances in sport science and nutrition” leading to “improved training practices.”


If the added weight is the result of widespread steroid abuse, that would be rather a more serious health problem than mere obesity. If it’s the result of advances in sports science and nutrition, then it would be no problem at all.

Either way, it doesn’t seem like something the general public needs to worry about. So the researchers say: But what about the children?

For a start, children, adolescents and many adults look up to professional baseball players. The increase in body mass might suggest that bigger is better and lead people to disregard public messages about healthy weight management.

Even if we ignore the very large caveat that professional athletes owe no duty other than to their employers here, and ignore the heavy labor being done by the weasel words “might suggest,” these authors must live on Mars if they think that America is going to trade in its robust fat-shaming culture for one where overweight people aren’t bombarded with messages that they are worthless.


But if it’s misleading messages about weight management that they’re concerned about, the researchers might think twice before telling genuinely obese people that they fall into the same health category as Mike Trout, whose 6-foot-2, 235 pound frame makes him obese, according to BMI.

Instead, the researchers insist that someone like Mike Trout is dangerously fat. “Players are endangering their long-term health by trading healthy body weight for performance-based rewards,” they write. They even have the gall to compare the importance of their research—a three-page, less-than-500-word research letter that cites six sources, fewer than I’ve cited here—to the research that uncovered the concussion problem in football.


They suggest that players and teams need to start tracking health data, which makes it clear that they have no idea how baseball or unions work (and no awareness that their own height-and-weight data set was supplied by organized baseball). They propose that the MLB Players Association should spend their bargaining capital negotiating for weight management programs, when most unions are busy fighting against management unilaterally imposing these programs.

Who wrote this drivel? David E. Conroy is a Penn State kinesiology professor and Mercedes R. Carnethon is a Northwestern epidemiology professor; neither holds an MD, as far as I can tell. The third author, Kathleen Y. Wolin, is the CEO of ScaleDown, which describes itself as “a remarkable new approach to weight loss” that uses “the science of self-regulation to help you lose weight quickly and easily.” Wolin is also the co-founder of Coeus Health, and “has a patent for a software platform pending.”


How does ScaleDown actually work? It’s simple!

It’s simple. Simply stand on the scale every day (yes, every day) right after you wake up. We’ll send you a text with feedback and tips that are personalized just for you. Each week, we’ll review your progress and give you highly personalized guidance to help you reach your weight loss goals. That’s it.

Oh, the CEO of a health management company based on weight-watching is using a bullshit measurement to argue that the MLB Players Association should ask for a weight-management program to be imposed in the next collective bargaining agreement.

Which one, I wonder, would she recommend they pick?