You can have some fat and still be healthy.

You’re 5’6”, eat a healthy diet, and work out at the gym three times a week. You weigh in at 155 pounds, which means that you’re at 25 on the Body Mass Index (BMI) chart—the chart that supposedly screens for healthy weight.  According to the BMI chart, you’re overweight. 

Are you?  Not really.  You’ve just run up against one of the many problems with using the BMI chart to decide if you weigh too much.  To understand why you look great and feel great but are officially too heavy, let’s take a closer look at why the BMI is actually a very poor measure of your health.

What Your BMI Doesn’t Tell You

To calculate your BMI, just take your weight in kilos, divide it by your height in centimeters squared, and then multiply that number by 703—a much easier method is to plug your weight and height into an online BMI calculator. If your BMI comes out below 18.5, you’re officially underweight; if it’s 18.5 to 24.9, you’re normal weight; if it’s above 25, you’re overweight, and if it’s above 30, you’re obese.

Really? All the BMI chart actually tells you is what your BMI is. It doesn’t tell you anything useful about your health, like how much body fat you have and where it’s located, or how fit you are. You could be very inactive with a lot of excess body fat around your waist (the most dangerous place to carry extra weight), but still be well within the normal range on the BMI chart. If you’re very muscular and fit with little body fat, you could fall into the overweight range. The BMI doesn’t take sex into account—and at the same BMI, women have more body fat than men.  Tennis star Serena Williams, for example, is 5’9” tall and weighs 165 pounds, giving her a BMI of almost 25—that’s just short of being overweight.  And come on, does a decimal point make the difference between being normal weight and overweight?

Waisting Time

The BMI is outdated and misleading: What’s important isn’t your weight as much as your waistline. The best indicators of both fatness and fitness are your waist measurement and your waist-to-height measurement. Guidelines from the National Institutes of Health now tell doctors to measure the waist of patients at their annual checkups.  Why?  Because the bigger your waist, even if you’re at normal weight according to the BMI chart, the greater your risk of heart disease, diabetes, and death from any cause.  

So forget the BMI chart and find a tape measure instead.

If you’re a woman, is your waist under 34 inches? If you’re a man, is your waist under 39 inches?  Yes?  Outstanding!  Not only is your weight normal, according to the American Heart Association, your risk of serious chronic disease is lower.

Now take it to the next level. Man or woman, compare your waist measurement to your height in inches. According to both the American Heart Association and the International Diabetes Federation, you want your waistline to be no more than half your height. So, if you’re 5’6”, or 66 inches tall, and your waist is 32 inches, it’s a bit less than half your height. You’re at a healthy weight for you, no matter what the BMI chart says. 

So can you just forget about the BMI chart? It still has its uses, says Sandy Amoils, MD, a physician at the Alliance Institute of Integrative Medicine in Cincinnati.  She explains, “The BMI is quick and easy to look up, and if it’s much higher than 25, it does indicate a weight issue and gives you a good idea of how serious it is.  But for most patients, the BMI is just a number on a chart.  I find that measuring the patient’s waist in the office has much more of an impact and is much more motivating when it comes to weight loss.” 

Sources: 

  1. BMI critique article in Circulation 2009
  2. CDC website
  3. International Diabetes Foundation guidelines
  4. Expert Panel Report: Guidelines (2013) for the Management of Overweight and Obesity in Adults, published in Obesity, Special Issue: July 2014,  Volume 22, Issue S2
  5. Dr. Sandy Amoils
  6. BMI calculator