Updated: Aug 22, 2022
You may have read that the most widely used tool to assess weight the Body Mass Index or “BMI” has serious flaws when it comes to assessing your healthy weight. So does that mean we shouldn’t use the BMI anymore? Probably not but for now we're stuck with using the BMI. Especially since our understanding of body fat metabolism and the disease of obesity is still in it's early stages.
Do you really know your healthy weight? If your first response was to say, "The BMI chart says..." Then you may not know your healthy weight. The BMI has its flaws, as we'll discuss in this blog post.
It's important to get your healthy weight right because many people base their weight loss goals on a certain number. If this number is too low, it can be harmful to your health. Also aiming for unrealistic numbers can lead to short term diets and unhelpful weight fluctuations.
I had a great time discussing "Deciding Your Weight Goal" on the Weight Solutions For Physicians podcast.
During a recent interview, I also shared my insights on the BMI and its limitations. Read more below:
1. What is the BMI, and what is it designed to do (or what do
most doctors say it does)?
"The BMI or 'body mass index' is a mathematical calculation of a person's weight divided by their height. The formula for BMI actually originated in 1832 from a Belgian anthropologist & mathematician, Adolphus Quelet. Quelet didn't intend the BMI for medical use. He just thought it was a cool observation for how people's weight changes proportional to height as we grow.
In the 1970's Dr. Ancel Keys wanted to help create a standardized way to measure health in the American population. Based on Dr. Keys' previous work in nutrition research, he thought weight would be a useful indicator of health since it was already being used by the insurance industry. Dr. Keys adopted Quelet's calculation and called it the 'body mass index' or BMI.
In 1985 the National Institutes of Health began to use BMI for health measurements.
BMI was created as a population-based health assessment, not an individual assessment. In other words, when we are looking at a BMI chart, it's a reflection of how much a group of people generally weigh, not what one person 'should weigh.' "
2. Why is it such a problematic measure of someone's overall
health? What does it not consider?
The BMI only looks at total body weight and doesn't account for body composition. When we look at someone's health risks, body composition is much more important than total body weight. Specifically, we need to know how much excess body fat someone has.
The data shows that while body fat is essential for body functioning, having too much can be harmful. The best measurements of health risk should be able to distinguish between harmful body fat levels and non-harmful levels.
3. Who does it harm, and how?
Since there are many differences in our individual's body composition, using the standard BMI chart is problematic for individual health assessment. The BMI can also be way off for certain groups of people, depending on your age, biological sex, race/ ethnicity, and certain metabolic health conditions. These factors change your body composition in ways that make it hard for the BMI to assess your health risk accurately.
4. What can doctors use instead of using the BMI to assess someone's health?
At Embrace You Weight & Wellness, we evaluate a person's unique Healthy Weight & Happy Weight. Healthy Weight is based on clinical facts. Happy weight is based on your unique feelings about your body.
When it comes to your healthy weight, we're looking at body composition, not just total body weight, so the number scale is less important. Thinking about where, what, and why a person's weight comes from gives much more useful measurements to assess someone's health.
Specifically, clinicians need to ask four questions :
-Where is the fat?
-What percentage and type of fat?
-Does this person have metabolic diseases such as hypertension, high cholesterol, insulin resistance/ diabetes?
-Is the person at their happy weight? How does the person feel about their body?
Where is the fat?
Check Waist circumference. Even if someone has a "normal BMI" having too much belly fat can increase your risk of metabolic diseases such as heart disease and diabetes.
What percentage and type of fat?
A body composition scale can distinguish different types of fat-subcutaneous (under the skin) or visceral fat around your organs. Knowing what type of fat and if you have a very high fat percentage is useful for assessing risk of metabolic disease. Very high body fat levels are also associated with increased risk of cancer and musculoskeletal disease.
Does this person have metabolic diseases such as hypertension, high cholesterol, insulin resistance/ diabetes?
Screening for metabolic diseases can be a clue that someone may not be in optimal health even at a "normal BMI"
Is the person at their happy weight? How does the person feel about their body?
Happy weight is not a clinical diagnosis but a personal one. Many factors influence a person's body satisfaction. Asking questions about body satisfaction can help assess mental health and screen for disordered eating.
BMI is still the most used tool for weight assessment worldwide.
If your doctor or clinician mentions your BMI:
Ask if the BMI chart being used has been adjusted to your unique features? If the BMI is used to assess health, a person's unique characteristic has to be considered and a specific, adjusted BMI chart for race/ethnicity, age, biological sex and obesity related diseases should be used as threshold for further health evaluation with the tools listed above.
Ask for your waist circumference to be checked. Where your body fat is located is important. Abdominal fat is associated with higher health risks.
Ask for your body fat percentage to be measured. You could use a bioimpedence scale like those used on Your Embrace You Weight & Wellness Journey or a body fat calculator. Methods of checking body fat are discussed in greater detail in Chapter 2 of Embrace You: Your Guide to Transforming Weight Loss Misconceptions Into Lifelong Wellness
Discuss if you have any metabolic diseases such as prediabetes, diabetes, hypertensions or conditions that place you at risk for metabolic disease such as PCOS. Regardless of how much you weigh metabolic diseases and metabolic disease risks need to be carefully evaluated.
For more information on this topic, check out chapters two and three of the bestseller, Embrace You: Your Guide to Transforming Weight Loss Misconceptions Into Lifelong Wellness. I discuss the limitations of the BMI as well as happy weight vs healthy weight in greater detail.
I'd love to hear your thoughts on the BMI and deciding your healthy weight.
Head to the Embrace You To Lasting Wellness and Weight Loss Facebook group to continue the discussion.
Related articles by/ featuring Dr. Sylvia (aka Sylvia Gonsahn-Bollie, MD, DABOM)
"The Weight of Motherhood: Black Maternal Wellness " Embrace You Blog
"Black Maternal Health Week" Embrace You Blog
"Overcoming Obesity Your Own Way" Embrace You Blog
"Obesity & Black Women: What Are We Missing?" Embrace You Blog
"How to Unlearn Weight Bias" Livestrong.com
"The Obesity Disparity & Black Women" Physician Weekly
"Why BMI Is Problematic for the BIPOC Community" Everyday Health
"Where Do We Go From Here: Impact of Racism & Racial Disparities on Obesity Rates in African Americans & Clinical Implications" Obesity Medicine Association Blog
"Clinical Conversations: Obesity In Black Women: What Are We Missing?" Obesity Medicine Association
"Your Weight Look Beyond the Scale" Lunch & Learn Podcast With Dr. Berry
"Does the Number on The Scale Determine Your Worth" S.O.S. Sisterhood of Sweat