Do You Know Obesity When You See It? Most Doctors Don't

Only 36 percent of Americans think they’re too heavy, even though data shows that 69 percent of us are overweight or obese. (Photo: Getty Images)

We live in a culture obsessed with weight. Fifty-one percent of American adults want to slim down, according to a 2013 Gallup poll. And nearly two-thirds say they exceed their ideal weight — the average woman tips the scale at 157 pounds but hopes to drop to 139, while the average man weighs in at 195 pounds but sees 182 as the ideal.

As a result, you’d think we’d be pretty darn accurate at sizing each other up. But new research suggests that most people — even health care workers — are unable to flag individuals who are overweight or obese.

In a new study presented at the 2014 UK Congress on Obesity, researchers asked 1,000 people to estimate the weight status of 15 different men, based on full-length photos. Although the study participants could generally spot normal-weight guys, they were significantly less accurate at classifying the men who were overweight or obese.

When they were wrong, it was almost always because they’d underestimated the weight of the person in the photo.

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This isn’t particularly surprising, especially when you consider another stat from the Gallup poll: Only 36 percent of Americans think they’re too heavy, even though data from the Centers for Disease Control and Prevention shows that 69 percent of us are overweight or obese.

“It’s become normal — the average American has a BMI [body mass index] in the overweight range, so it doesn’t strike us as at all unusual to see somebody overweight,” said Dr. Lawrence Cheskin, director of the Weight Management Center at the Johns Hopkins Bloomberg School of Public Health, who wasn’t affiliated with the study.

And even though we love to critique each other’s physiques, we don’t have a reliable way to do so visually—at least from a medical perspective. “There isn’t any obvious standard or visual way of knowing what different weights look like,” study author Eric Robinson told Yahoo Health in an email. That means we may resort to comparing people with “normal” folks we know, and if they’re clearly heavier, classify them as overweight. “[This approach] probably won’t work, because the ‘norm’ now is actually to be overweight,” he said.

In a second study, published in the British Journal of General Practice, the researchers decided to put 315 general practitioners and their trainees to the same test. The results weren’t encouraging: On average, they placed only about half — 8 out of 15 — of the men into the correct BMI category.

Why that’s alarming: If doctors are unable to spot obesity, they may end up overlooking a large number of patients who could use help losing weight. In fact, in the study, the doctors said they’d propose a weight-loss regimen to only 29 percent of the guys in the photos, even though two-thirds of them were overweight or obese. “One of the benefits of going to your care provider is that they can point out areas where you can improve your health,” Cheskin told Yahoo Health. “We’re not doing a good job of that, because we’re not recognizing obesity. And that’s a problem.”

In real life, doctors’ judgments may be even less accurate, the researchers warn, since actual patients are more likely to be wearing loose-fitting clothing and sitting down, compared with the men in the photos, who were sporting tighter garments and standing up. “It can be hard to notice [weight] with street clothes,” said Cheskin. “And we are not often trained as care providers to pay that much attention to someone’s weight. We’re more focused on assessing what they came into the office to have dealt with. Their weight is very much on the backburner.”

While the photos in the studies were all of men, Cheskin speculated that doctors may struggle even more to identify overweight women, who often carry any extra pounds in their lower body, rather than the gut that men tend to develop. “The woman might just look a little curvier,” he said. “That guy who’s got a big belly — that’s a little more obvious.”

However, this study may also simply reflect the inherent problems with BMI, which takes only height and weight into consideration. “It doesn’t take into account how much of that weight is fat, how much of that weight is muscle, how much of it is fluid,” said Dr. Eduardo Grunvald, a primary-care physician and director of the UC San Diego Weight Management Program. Translation: If you take a 70-year-old man with a BMI of 29, which is considered overweight, he’ll likely look overweight, since much of his weight is probably fat. But a 30-year-old man with the same BMI might not visually register as “fat,” since he has more lean tissue left.

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“I don’t think that visual inspection is a great way to screen someone, especially in young men who are just overweight or mildly obese,” Grunvald told Yahoo Health. “BMI is not a great clinical measure” — meaning it doesn’t necessarily reflect the health effects of excess weight — “but it’s a good screening number to then dive deeper into what kinds of problems the patient may be having.”

While doctors should certainly consider patients’ BMI, they should use that number only as a jumping-off point to determine how their weight is affecting patients’ lives: Are they suffering from “fat mass” problems, like sleep apnea, joint pain, or acid reflux? Is the excess weight causing high cholesterol, blood sugar, or blood pressure? Are they depressed or socially inhibited as a result of their size? “It’s not really about weight per se, but how that weight is causing problems for that patient, either currently or in terms of risk down the line,” said Grunvald.

What makes the study’s findings especially worrisome is the fact that overweight folks are already less likely to seek care, which means doctors have fewer opportunities to treat them in the first place. And even when it is obvious that a patient is obese, doctors may be hesitant — even embarrassed — to point it out, especially if the doctor is obese, too. “If you’re sitting there smoking a cigarette, you’re not going to turn around and tell somebody to quit smoking,” said Cheskin. (However, in the study, doctors’ weight didn’t influence their likelihood of talking to a patient about weight.)

If you’re worried about your weight, the most reliable visual cue is your waistline. Although the size of your waist won’t help you estimate your BMI, it can indicate whether your weight may be posing a risk to your health. Doctors call excessive fat around the midsection “visceral adiposity,” which has been linked to diabetes and heart disease, even in people with an otherwise normal BMI, said Cheskin.

But your best bet is talking to your doctor about what you can do to improve your health. And, hopefully, in the near future, weight management will become a routine part of interactions with your primary-care doctor. “Frankly, you shouldn’t have to ask that — we should be doing a better job,” Cheskin said. “[BMI] should be no different than the vital signs — you take somebody’s blood pressure, and you measure their BMI.”

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