People often worry about their body mass index when they shouldn’t.
Say you’re five feet, eight inches tall and weigh 200 pounds. You’ve got a BMI of 30.4, which says you’re obese.
If you’re active and well-muscled with strong bones, you probably aren’t anywhere near obese. But if you’re a couch potato who is out of shape and carrying around a lot of excess belly fat, well, then the BMI got it right for you.
It works just the opposite, too.
This time, let’s put you at five feet, eight inches tall with a weight of 150. Congrats! You’re at a healthy 22.8 BMI. But are you really? Or do you fall into this category because you aren’t getting the nutrition you need, your muscles are wasting away, and your bones are not as strong as they should be because of inactivity?
What I find is that the BMI can be useful when you’re looking at a very large dataset. But it starts to fall apart when you try to individualize it.
For example, when studies actually looked at health biomarkers in people who are overweight or obese based on their BMI, they found that nearly 50% of them were completely healthy. Their blood pressure, triglycerides, cholesterol, glucose, insulin resistance and C-reactive protein data were all fine.
At the same time, about 30% of people with “healthy” BMIs actually had poor markers of health.
If I had to hazard a guess, I’d say these are the people who defy the nature of the body mass index – which only performs a rough height/weight calculation without taking anything else into account. So judging their health and weight by BMI is inaccurate and misleading.
BMI Isn’t the Best Marker of Weight and Health
BMI alone should never be a used as the sole marker of your health or weight.
If you have a fit and muscular build, the BMI can clock you in as overweight or obese. Conversely, if you’ve lost muscle, bone mass and gained belly fat with age, you may fall well within normal ranges on the BMI scale, but still be very unhealthy.
Plus, it doesn’t work well in people who are very short or very tall. It tends to give short people BMIs that are too low, and exaggerate BMI in people who are tall. Just consider this… someone who is 6 feet, 5 inches tall and weighs 160 comes out with a “normal weight” BMI. But if they weigh 220 pounds, they are overweight. There’s no way that can be right.
Ultimately, BMI simply doesn’t take into consideration the structure of your body – how much of it is muscle and bone mass, how much is fat, what kind of fat it is, whether you are an “apple” or a “pear.” It doesn’t have any gray area.
More specifically, there are different kinds of fat in your body. The most dangerous type is called “visceral fat.”
This is the type of fat that builds up in your abdominal area, giving you an apple-like shape. We call it abdominal obesity, and even people with a “normal” BMI can accumulate it. This is often referred to as “skinny fat.” But it’s still just as dangerous.
It creates an inflammatory environment. It’s the type of fat that is linked to heart disease, insulin resistance, type 2 diabetes, cancer and dementia. It can kill you.
So BMI is just a tool. And it should be used with other measures to evaluate your overall health. BMI alone will not tell you the entire story.
Get a Better Measure of Your Health and Fatness
Make no mistake about it. Weight is a huge health concern here in the U.S. During the period between August 2021 and August 2023, nearly 41% of U.S. adults were obese.
But it’s also important to recognize that visceral fat is the kind that is going to do the most damage.
So what you really want to do is measure visceral fat – or belly fat. And there are two super-easy ways to do this.
The first is the waist-to-hip ratio.
You simply measure your waist at its smallest circumference. Then measure the widest area of your hips. Write those numbers down.
Then plug them into a waist-hip-ratio calculator to find out where you fall. If you are in the moderate or high-risk category, it’s important that you start making some changes in your life.
Any number above .90 in men and .80 in women increases the risk of developing a serious health condition. The higher the number, the greater the risk.
The second measurement is the waist-to-height ratio.
The concept is very similar. Measure your waist at its smallest circumference, then measure your height. Put those numbers into a waist-height-ratio calculator and it will tell you where you stand
The number should be lower than .50. The higher the number beyond that, the more chances of developing life-altering health problems and losing years of life.
If either or both of these numbers is high, it’s a call to action to get serious about dropping that dangerous belly fat.
SOURCES:
Stang AJ. Is it Time to Say Goodbye to BMI? Plast Reconstr Surg Glob Open. 2022 Jan 21;10(1):e4039.
Tomiyama AJ, Hunger JM, Nguyen-Cuu J, Wells C. Misclassification of cardiometabolic health when using body mass index categories in NHANES 2005-2012. Int J Obes (Lond). 2016 May;40(5):883-6.
Emmerich SD, Fryar CD, Stierman B, Ogden CL. Obesity and severe obesity prevalence in adults: United States, August 2021–August 2023. NCHS Data Brief, no 508. Hyattsville, MD: National Center for Health Statistics. 2024.
Pray R, Riskin S. The History and Faults of the Body Mass Index and Where to Look Next: A Literature Review. Cureus. 2023 Nov 3;15(11):e48230.
Ashwell M, Mayhew L, Richardson J, Rickayzen B (2014) Waist-to-Height Ratio Is More Predictive of Years of Life Lost than Body Mass Index. PLoS ONE 9(9): e103483.
