Lessons From Cupid: Where BMI Goes Wrong

14 Feb
Today is Valentine’s Day and no, I’m not going to flash any food porn involving chocolates. But with Cupid hovering around lately, I couldn’t help but address the subject of BMI, Body Mass Index.
What if Cupid and his parents showed up in my office concerned about obesity? What would I say? Let’s assume for a moment, from the various images of him, that his BMI would be in fact high. For the record, BMI is simply a calculation of weight divided by height squared, used as a marker for obesity. It is not, as you have been lead to believe, a measure of body fatness or percent body fat.
If historically, as evidenced by Hallmark’s greeting cards, Cupid has always been husky from his youngest years, here’s what I’d say: Assuming he has paralleled the BMI chart, he is gaining as much annually as any other normal healthy child. It’s just that he started larger—simply genetics, most likely. I would still explore his intake and eating behaviors, recommending modifications to ensure health and prevent disease (just as I would do if an average weight individual presented for, let’s say, food allergies). But if all looked well, I would not create a problem where there was none.
If, however, I discovered he was hoarding the chocolates he planned to deliver, binge eating or emotionally overeating (perhaps because of unrequited love), these patterns would need to be addressed—with me and with a therapist.

Okay, maybe a LITTLE bit of food porn...

Like chocolates, we come in all shapes and sizes. And if your size, like Cupid’s, has always leaned toward the larger end of the spectrum, it is likely that is a healthy and normal place—for you. If, however, you have never listened to your hunger and fullness, tending to regularly use food for comfort or to manage stress and emotions, there’s room for changing your relationship with food—and as a result, your weight.
Maybe as an adult your BMI is out of range, placing you in the “obese” category. That puts you in good company with top paid professional athletes such as Vince Wilfork and Charles Barkley. BMI is hardly the best way to gauge your size, or your risk of disease. Many with high BMI’s are quite healthy and fit, often at the top of their games. BMI may be high simply from a high muscle mass. Remember, body mass index does not distinguish where that mass comes from—muscle or fat (or bone, for that matter).
Years ago a woman who did body building recreationally came in for assistance with weight loss. It was winter, and quite frankly I could never have visually guessed what her risk was. By the charts, she was obese with a high weight for her height. But when I assessed her eating, I could only conclude that she wasn’t eating enough, regardless of her weight concerns. Weeks later, following a half marathon, she reported that she was hospitalized with internal bleeding. Apparently, her percent body fat was so low that there was damage to her internal organs, resulting in the bleed. Yes, body fat does have a function, and cushioning our internal organs is just one example.
But if your weight has been climbing out of a healthy range, and you have not dramatically increased your muscle mass, it may be time to take a closer look at your activity as well as your food intake and eating behaviors.
And we should be most focused on an individual’s pattern, as opposed to their absolute weight or BMI. I had a teen patient not long ago who presented at the 50th percentile BMI for age. Great, no? His doctor thought so and was quite pleased with his healthy place on the chart. But a look at his BMI chart revealed that he had plummeted in a very short period from a high BMI to “normal”. Unfortunately, this drop resulted from anything but normal thoughts and behaviors around food; it was rather the consequence of a full-blown anorexia. Reinforcing how “healthy” his recent BMI was only added flames to the fire.
As for the adult Cupid, waist circumference, or waist to hip ratio, would likely tell me more, being suggestive of abdominal fat and its associated risk with chronic diseases, including Type 2 diabetes. A waist circumference above 35 inches (women) and 40 inches (men) is considered a predictor of increased risk. The waist-to-hip ratio—literally, your waist measurement divided by your widest hip measurement—is also a good predictor of risk. 1.0 or above is greater risk, and desirable is 0.8 for women and 0.9 for men.
But perhaps the best measure to use would be percent body fat (most accurately determined by underwater weighing but indirectly measured with calipers or more high tech devices). And yet I rarely recommend it. Why? Because we really don’t need another measure, another number to fixate on. If your weight is climbing out of range, you’ll know it. Take a look at your eating patterns and activity. Focus on eating mindfully and separating physical hunger from all the other reasons you eat.
And if your weight is above a “desirable” BMI, but has been stable for years and you have normal blood pressure, cholesterol, and blood sugar, let it go. As long as you can comfortably engage in activity to keep you strong and fit for years to come.

4 Responses to “Lessons From Cupid: Where BMI Goes Wrong”

  1. Ben Radford February 17, 2012 at 2:13 pm #

    Interesting piece… there’s a lot of misinformation about the BMI, good to get some facts sorted from the myths. However there may be a mistake here:

    “But perhaps the best measure to use would be percent body fat (most accurately determined by underwater weighing but indirectly measured with calipers or more high tech devices). And yet I rarely recommend it. Why? Because we really don’t need another measure, another number to fixate on. If your weight is climbing out of range, you’ll know it.”

    Most people believe that with Americans so fixated on their weight, people (especially women) would be very aware of every new ounce and pound, but recent research suggests it’s not true.

    In fact studies suggest that many people are not aware of significant weight gain, and therefore it’s not true that if your weight is climbing out of range, you’d know it.

    For example here are excerpts from two news stories reporting on recent studies:

    1) “According to a new research study, nearly four in 10 overweight women believe themselves to be thinner than they really are. The study’s authors, Mahbubur Rahman and Abbey Berenson, surveyed 2,224 women between 18 and 25 years old from a variety of ethnicities. Using the subjects’ calculated Body Mass Index (BMI) and self perception of weight, overweight and normal-weight women were divided into four categories: overweight misperceivers (overweight women who described themselves as underweight or normal weight), overweight actual perceivers (overweight women who described themselves as overweight), normal-weight misperceivers (normal-weight women who described themselves as overweight), and normal-weight actual perceivers (normal-weight women who described themselves as normal weight or underweight). The researchers found that 36.8 percent of the overweight women (and 10.5 percent of the obese women) believed themselves to be underweight, or of normal weight.”

    Self-Perception of Weight and Its Association With Weight-Related Behaviors in Young, Reproductive-Aged Women. Rahman, Mahbubur MBBS, PhD; Berenson, Abbey B. MD, MMS. Obstetrics & Gynecology: December 2010 – Volume 116 – Issue 6 – pp 1274-1280



    2) “Despite popular belief about women’s weight concerns, young women commonly fail to recognize recent gain of as many as 11 pounds — putting them at risk for cardiovascular disease and other obesity-related conditions. Self-perception of weight gain also appears to be significantly influenced by race, ethnicity and contraceptive methods. 
In a study published online and in the March issue of the Journal of Women’s Health, University of Texas Medical Branch researchers found that a significant number of women evaluated at six-month intervals did not recognize recent gains in weight. 

Overall, nearly one-third and one-quarter of women did not recognize gains of approximately 4.5 and 8.8 pounds during a six month interval, respectively.”


    There may be other research suggesting that people’s self-estimates of weight are accurate, but these seem to suggest that for many people they’re not. Of course this has implications for the obesity epidemic, because if doctors are assuming that overweight or obese patients are aware of their weight, that may not be true.

    • hikerrd February 17, 2012 at 2:35 pm #

      Point well taken. However, for segments of the population that I work with, namely the eating disorder population, fixating on yet another measure is the last thing needed. In general, acknowledging changes in weight has its value. That is, if the individual can put the weight or change in BMI in perpective, and create a plan for healthy change. All too often though people fixate on even subtle increases in weight. The consequence is self-sabotage of any healthy behaviors they have achieved. By itself, BMI has limited value. It should be used to flag those who might be at increased risk for other medical conditions. But if those measures are within normal limits, dwelling on changing their BMI has little merit.

      • Ben Radford February 20, 2012 at 12:08 pm #

        Yes, I see what you’re saying, and I agree with you. I didn’t realize you were referring to the eating disorder population. As I recall they typically chart high on scales of perfectionism (and depression), and having one more measure by which to judge themselves is not helpful. I think most people would agree with you that dwelling on BMI (or any other health indicator) is unhealthy. What I often encounter (especially in the fat acceptance fields) are people claiming that the BMI is worthless, which is categorically not true. When used for its intended purpose it can be very valuable.

  2. LKL June 2, 2012 at 12:20 am #

    In 1995, I was 5’5″ and weighed 160 lbs; I was eating more than a pound of food per meal. I was also in the best shape of my life; I was on a varsity crew team, and had 1-2 hours of aerobic training every day except Sunday (not including the time it took me to walk or bike to the boathouse, or the time it took me to walk between classes on campus).

    A year later, I was still 5’5″ and 160, but I had taken a sedentary job with the state Department of Agriculture that had me driving 8 hours a day and mostly stopping at fast food joints for meals and snacks.

    Same BMI. Same body. Very different levels of health.

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