As I train for another marathon, I’ve been getting very into all things body, wellness, and fitness. Currently on my list: Body mass index, also known as BMI.
You’ve probably heard of this for years as the standard health assessment tool. And although it has been used for decades, it has been widely criticized in the industry for failing to tell the whole story. Many believe BMI is outdated and inaccurate and shouldn’t be used any more. Below, we dive in.
What is body mass index?
Developed in 1832, BMI is a scale that estimates the degree of overweight and obesity in a given population. Lambert Adolphe Jacques Ouetelet, the founder of BMI, actually stated that BMI should not be used when studying an individual, instead only on a population.
Based on a mathematical formula, it will show if a person is healthy by dividing their weight in kilograms by their height in meters squared. The equation looks like this:
BMI = weight (kg) / height (m2)
Once your BMI is calculated, it’s then compared to the below scale to see if you are normal, under, or over the average weight.
|BMI range||Classification||Risk of poor health|
|less than 18.5||underweight||high|
|25.0–29.9||overweight||low to moderate|
|30.0–34.9||obese class I (moderately obese)||high|
|35.0–39.9||obese class II (severely obese)||very high|
|40 or greater||obese class III (extremely obese)||extremely high|
Your doctor might suggests changes to your diet or activity level if you don’t fall in the normal weight category. The issue with the scale is it doesn’t consider age, sex, race, genetics, fat mass, muscle mass, or bone density — highly important factors.
Okay, so what else does it not do?
Sadly, BMI only answers yes or no questions regarding a person’s normal weight. Relying only on BMI will risk the chance of missing important measurements like blood sugar, cholesterol, blood pressure, heart rate, and inflammation levels.
Not to mention, with age, body fat naturally increases, and muscle mass naturally declines. BMI also doesn’t know what’s fat and what’s lean muscle. For example, someone who is 200 pounds and is 5’9′ has a BMI of 29.5. That would be considered overweight, when in reality, they are in good shape.
BMI doesn’t consider fat distribution either. People with fat stored around their stomach area have a greater risk at chronic diseases than those who store in their bums, thighs, or hips. In addition, BMI might not be relevant for all populations of adults.
Using only BMI to determine someone’s health also ignores the mental well-being of the person and sociological factors like income, access to nutrients, and living environment.
Ok, so what should I use instead of BMI?
Glad you asked. Instead of using BMI, we suggest measuring your waist circumference, waist-to-hip ratio, or body fat percentage.
A waist circumference greater than 35 inches in women or 40 inches in men, indicates greater body fat in the abdominal area—the area associated with a higher risk of chronic disease. You can measure your waist circumference with a measuring tape.
A waist-to-hip ratio greater than 0.80 in women and 0.95 in men indicates fat stores in the stomach area. A low ratio, lower than 0.80 for women, and lower than 0.95 in men suggests higher hip fat storage, which is better for your health.
Body fat percentage
Body fat percentage shares the amount of body fat that you have. It can be measured with assessment tools like skinfold measurements and at-home scales.
How are you incorporating wellness into your routines this year? If you’re looking for some exercise tips, don’t worry, we got you. And if you’re looking for the right equipment for home workouts, we got you there, too.