Go search up an article about bariatric treatments and you’ll find that the first paragraph usually begins with something like: “Obesity affects more than 600 million people worldwide” or “Over 200 million of the US population is considered overweight or obese”. Having read my fair share of literature about obesity and bariatrics over the past couple of years, guessing whether or not the next article will begin with a similar statement has become a game to pass the time with as I wait for it to load on my computer. And while such statistics about obesity are unfortunately true, stating them as a preamble in peer-reviewed research or by medical device companies in marketing content can be both deceptive and naïve.

Now to be fair, I understand why these wow-inducing statistics are used, and I don’t intend to fault those who do. In order for a paper to be published in a reputable journal, certain standards need to be met; namely, start with an introduction where the context is explained and a brief review of literature presented. In order for a medical device company to receive funding for developing and trialing the next innovative device aimed at treating obesity, potential investors need to be convinced that there exists a (large) market opportunity where they can eventually benefit from some return.

But like the bloated Chinese stock markets that have recently collapsed, I worry that the common view of the obesity market and its market potential has been overly propped up by our romanticization of prevalence statistics.

“Many a statistic is false on its face. It gets by only because the magic of numbers brings about a suspension of common sense.” —Darrell Huff

To realistically determine the market potential of any obesity treatment, and ignoring for a moment the feasibility and economics of it, we need to consider the size of the true treatable patient population, which is dependent on knowing the profile of a typical obese patient, as well as the likely indications of a surgical intervention or device. For example, about 80% of patients who undergo bariatric surgery are women. If we look at the patient demographics in the pivotal trials conducted for two recently approved intragastric balloons—ReShape Medical’s ReShape Duo and Apollo Endosurgery’s ORBERA—a similar proportion emerges. With that in mind, to rely on the fact that approximately 90 million people in the US are obese would conceal the somewhat sobering idea that only about 45 million of them are women.

Sure, 45 million is still a huge patient population, but how about the class of obesity? Most insurers will only cover bariatric surgery if the patient has a BMI of 40 or greater (class 3) or a BMI between 35 and 40 with at least one significant weight-related condition, such as obstructive sleep apnea or type 2 diabetes. These indications are the case for EnteroMedics’ vBloc Maestro implant, which was FDA approved this January, but the device is further constrained by an upper BMI limit of 45. While indications can later be expanded, it can take a very long time, as exemplified by the LAP-BAND.

For people at home keeping score, the epidemiologists at my company estimate there are about 10 million class 3 obese women in the US. Still think the market is huge? Let’s not forget about age. Again, insurers and bariatric surgeons primarily accept adults who are not at risk for surgical complications—the median is somewhere between ages 40 to 45—which means that surgery performed on people under the ages of 18 or over 60 are rare, although this is slowly changing and gaining greater acceptance.

Finally, there is the requirement—both from the insurers and surgeons’ standpoint—that patients must have documented past failed attempts at weight loss using less drastic means (e.g., diet, exercise, drugs) and are willing to commit to post-intervention follow-up. Only then is a patient considered fit for bariatric treatment.

Don’t get me wrong. I confess I have an optimistic outlook for the bariatric market. So while I may sound like the world’s biggest party pooper, I feel that given the FDA’s approval of three devices aimed at treating obesity this year, and with more novel devices in the pipeline to come, it’s prudent for investors, innovators, practitioners, and companies interested in this market to consider some simple math and to not be swept off their feet by “2/3 of the US population” being overweight or obese.

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