I love hearing from all of you, especially when you respond with requests for topics you’d like me to cover.
Recently, one of my blog readers asked about the BMI chart – and specifically if it was outdated and if she should strive to weigh what’s recommended for her height on the BMI chart.
Her question is a great one. MANY people start with the same question when they begin their weight loss journey.
WHAT IS THE BMI CHART?
BMI stands for “body mass index” and it’s supposed to provide an easy way to measure if someone is underweight, overweight, or obese.
The chart is supposed to be able to estimate the amount of body fat someone has based on their height and weight, and with that number they are then placed in an appropriate category. If you fall below 18.5, that means you are underweight. If you fall between 18.5 – 24.9, that corresponds to the “normal” category and anything 25 or above will put you into the overweight or obese categories.
Here’s an example of a BMI chart:
If you don’t fit in the “recommended range” for your height, do not fear. I will tell you why this chart is completely bogus and outdated, and how you should check your progress instead.
WHEN WAS THE BMI CHART INVENTED?
Body Mass Index was originally devised in the 1830’s and it’s said to estimate how much fat you have by dividing your weight in kilograms by your height in meters squared.
There were some known flaws in the formula for many years, but that has not stopped the medical profession, and the insurance companies from using this chart to determine what the rate premiums should be for their members (more on that below).
TOP 3 REASONS WHY THE BMI CHART IS BOGUS
There are multiple reasons why the BMI chart is outdated, but in the interest of email length, I’m going to include the top 3 here. Even with the top 3, that should be enough to convince you that you no longer need to stress over the BMI chart anymore.
1) The BMI chart doesn’t take into account what your body weight is made up of: bones, fat, muscle, etc.
The BMI chart does not distinguish between bone, muscle, or the weight of body fat. Bone is more dense than muscle and muscle is twice as dense as fat. The problem we run into is if someone has strong bones and a large amount of muscle tone (a good thing!), but a low body fat percentage, the chart may say they are classified as overweight or obese. This has happened to many famous athletes.
2) The BMI chart doesn’t take into account your activity level
Someone who is not very active, and has low levels of muscle tone, but looks thinner, with higher levels of body fat, can show as “healthy” on the BMI chart.
3) Insurance companies sometimes charge higher premiums for people with a high BMI.
This is the reason that makes me the most angry. Even though current research shows the BMI chart is bogus, many insurance companies still use it to determine rates. For those who are fit, with good muscle tone and little fat (who are usually the healthiest folks around), they’ll get stuck with greater premiums if their muscle weight puts them in the “overweight” category on the BMI chart. The insurance companies are not in a hurry to change this, as it helps them get more money for premiums.
WHAT YOU SHOULD USE INSTEAD OF THE BMI CHART?
There are two methods you can use that are more accurate than the BMI chart.
The most accurate is the the DEXA scan. It will do a great job measuring how much body fat you have, but the test tends to be pricy.
My favorite (cheap) alternative to the BMI chart is taking your waist-to-hip ratio. It may not be the fanciest or as accurate as a DEXA scan, but scientific studies show this method is more accurate than the BMI chart. It’s also more accurate than the waist measurement alone to indicate good health.
Take the circumference measurement of your waist (most narrow part). Then divide it by the circumference of your hips (the widest portion). For example, if your waist is 33 inches and your hips are 41 inches, you would take 33 divided by 42. That would equal 0.80. The goal is to not have ratio above 0.80 for women & 0.95 for men.
By now you see there are many more accurate ways to measure good health. You do not have to rely on the outdated BMI chart anymore.