Tuesday, February 15, 2011

Where BMI Goes Wrong. Lessons From Cupid.

Yesterday was Valentine’s Day and no, I’m not going to flash more 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 these days that his BMI was 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.

Like chocolates, we come in all shapes and sizes. And if your size, like Cupid’s, has always leaned on 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 game. 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, visually I could never have 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, but rather the consequence of a full-blown anorexia. And 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, suggestive of abdominal fat, and associated with chronic diseases including Type 2 diabetes. A waist circumference above 35 inches (women) and 40 inches (men) it 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, 0.9 for men. See

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. Reread some past posts on this blog for more guidance!
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.


  1. Thank you for addressing BMI. You're so right that the last thing we need is another number to obsess about. I'm not even going to calculate my BMI because I know that I will obsess about it and compare it to others'. I love the colorful example of Cupid!


  2. Good move, Emily! And so glad to have you as a new follower, Ashley!

  3. I have decided that BMI is my enemy --- and it frustrates me that it is still all over if it is so inaccurate. Some physicians still use that as a true measuring point - but why?
    My ED still causes me to obsess and worry about numbers, and even after two years of working at recovery and moving forwards by leaps and bounds, I cannot let go of the scale or numbers. I worry about it, a lot. And it is frustrating.
    It certainly makes me feel better to read things like this, so thank you for posting about it.

    I am definitely an athlete, but I do not consider myself really strong. After I got to a certain point in recovery I was allowed to exercise again, and it certainly increased my weight - which was not what I was looking for. I am a competitive athlete and love what I do, but at the same time, I hate what it does to my weight (not enough to give it up though) ... my RD tells me the weight gain is muscle and that I am incredibly strong ... a lot of people tell me how string I am ... but I just don't see it.

    It is a frustrating road and I should probably just let the numbers go, but I am not sure I can until I can find some way to know that it is muscle and I am not just fat.
    I am still in my normal BMI - just at the higher end of it - and it stresses me out.

    Wow - this obviously hit a nerve with me. Sorry about the rant.

  4. Thanks for posting this. My 8 year old son weighs 87 pounds. He is above the 100 percentile on the BMI chart, as his height hovers around the 90th. My husband is giving the child a complex about his weight, forcing him to engage in sports, watching everything he puts into his mouth. The thing is, my husband is a very fit, 240 lb man, at just under 6 feet. He is very broad and muscular, and his father before him was even bigger, with a massive head, hands, and feet. I can hardly find shoes or hats to fit my son. Our doctor merely shrugged when I brought him in to be evaluated. Our son has a massive growth spurt at the age of 4, gaining about 20 pounds in a matter of 3 or 4 months following a tonsilectomy, and has had a slow but steady incline ever since. I think he's normal. My husband thinks he's fat, because the other boys in his class are all slim and in between 60 -70 pounds. I should add here that he was breastfed until he was two years old and hardly ate anything solid until he was over a year. We aren't obsessive, but don't keep junk food in the house,other than the odd granola bar or a low fat hotdog here and there. He does have a very large appetite. Do I worry? What more can I do about it? He walks to school, plays organized sports 3 times a week, and has gym class each day. Do I deny food to a child who tells me that he is hungry? A child with his large build would have a larger appetite than a smaller framed boy, no? Do I take away his wii and make him run laps around the neighborhood? I think our obsession with weight and BMI has gone too far....

  5. Yogini,
    If you really need confirmation that your weight is muscle, have a reputable person do a percent body fat. But honestly, you're likely to take issue with that number as well. It's really self-acceptance that needs addressing, not another measure!
    Hopefully, you'll find some solutions to your concerns in this very post!
    Regarding "denying your child when hungry" the answer is no! Don't say to your sons or daughters "you don't need it" or "you've had enough!". Rather, suggest that they give their bellies some time for the food to get there, and assure them that if they are still hungry later (about 45 mins) then of course they will eat again. Meanwhile, move from the kitchen and engage in another activity. If they remind you they are hungry later, then please honor it and feed them! Half the time they will forget, and many times they will realize they aren't hungry.It really works! And you'll feel better avoiding the conflict!

    Hope that helps!

  6. What a creative way to talk about an important issue! Thanks for helping to "reframe" our obsessions with numbers and the way that we think about health.

  7. Thank you so much for this post! I have been telling my kids they have had enough and making them wait for snacks out of fear of over feeding them. I really thought it was the healthy thing to do. I also have one kid (out of my five) who trends in the 85th percentile for height/weight. Her doctor says she wants to see her at 85th percentile or lower which struck me as odd knowing that the growth chart is supposed to be the whole range of normal. When is normal not "normal" enough?

    1. Apparently someone understands these charts! You are right on!
      Feel free to share this post with your pediatrician!

  8. What a clever and insightful post! And I'm really enjoying Food to Eat--it's a fantastic resource. (Now I need to make some of those delicious-sounding recipes!)

  9. Thank you for this! As two occupational therapists with a blog on childhood obesity ( we believe that the way to deal with obesity is to increase awareness of how our daily habits contribute to weight gain and how as a family we can work together to take responsibility for our part in solving the obesity epidemic threatening to bankrupt this country.