You're probably familiar with the BMI or the body mass index, for which clinicians or even your employer's wellness program or life insurance policy, will measure to determine your overall risk status based on your weight. BMI is also used to determine your eligibility for weight loss medications, and it can affect access to joint-replacement surgery and fertility treatment.
The Centers for Disease Control is a big proponent of the #BMI, as is most other professional organizations and it is the standard for evaluating health risk related to weight by most all third party payers. It is an inexpensive and easy screening. When your focus is a larger population, BMI may be a helpful too, but when we want to evaluate individual risk, the BMI is not our best tool.
The BMI measures height and weight and then based on a population, made up mostly of Caucasian adults, your risk status is quantified into a number. The literature does in fact seem to support the BMI as a tool for identifying those at risk for various metabolic and disease outcomes particularly at the higher range of the scale, again, among a population of people, but it does not diagnose the body fatness or even muscle mass of an individual so it's a picture that suggests risk more than it is an absolute.
My concern though, and the concern of many clinicians, is less for those at the higher end of the BMI scale, because one way or another when the numbers are high this is usually related to higher percentages of #adiposity which does pose risk for chronic disease, but rather those that fall within a more normal range when they are in fact more of a "skinny fat." The American Medical Association adopted a new policy on the index in June of 2023. They state that there are "significant limitations associated with widespread use of BMI in clinical settings," and they appreciate its "historical harm" and "use for racist exclusion."
When our healthcare system is overworked, doing a more thorough evaluation of body composition is not likely to be a priority in the typical wellness exam either, nor is explaining the nuances with utilizing body mass index, but offering the BMI is really pretty antiquated. The challenge is that equipment for evaluating body composition can be expensive and these assessments are not reimbursable.
Obesity, like all disease, is complex and cannot be captured with a single measurement. There are risks such as heart disease, hypertension, metabolic disease, obstructive sleep apnea, and type 2 diabetes. BMI doesn't account for gender, where people carry fat, and many feel strongly that the BMI measurement in itself is racist. It isn't good science to extrapolate results from one group to another without validating the science in the target population. This was also done for newborn growth charts, which were based on thirty Caucasian babies born in Ohio.
Evaluating the Individual
My own BMI is increased. I do have a fair amount of visceral fat which accumulates around the middle due to stress or higher levels of cortisol. Being on call for more than a decade, attending births at all hours of the night for days sometimes at a time, really stressed my endocrine system. However, because I have always enjoyed working out, I have a high bone mass and a higher muscle mass so all my readings, including my overall body fat are within normal limits. These variables combined though place me in the #overweight to obese range on the BMI scale, yet I have clients with double the body fat measurement who fall within a healthy BMI range. This is misleading and dangerous in a number of ways.
Individuals may neglect to self-evaluate if they are falsely reassured, but also, those with findings such as my own may cause some to unnecessary restrict calories or struggle to maintain a healthy body image. I do need to lose my visceral fat, but I also know by body is strong and without pain. I am grateful for the journey my body has carried me through, and my journey is to better honor myself, to better prioritize my health, and to have compassion for myself because I have endured a significant amount of stress in my life, which is evident in my waistline.
Many times I'll meet with women who carry more weight around their hips and bum, even their thighs and more often this is more representative of an estrogen, progesterone, or even #testosterone imbalance. Large arm circumference, particularly when the arms are similar in size to one's legs, is typically representative of insulin resistance. This is my own clinical experience though, very anecdotal, and as I am aware not yet scientifically evident. Those roles on the back, particularly the back of the neck, a larger bust line and especially a larger waistline is often cortisol, which leans into blood sugar as well. The belly fat can also be broken down into mommy belly, cortisol/stress belly, and beer belly.
We also know that women tend to have more body fat than men, race and ethnic background can alter the body fat at the same BMI, older people tend to have more body fat than those in their younger years, and athletes have less body fat than do non-athletes. Athletes may have a high BMI because of increased muscularity rather than increased body fatness, but they would still be classified as obese.
Measurements such as waist circumference, measurements of visceral fat, body composition, and genetic and metabolic factors are better indicators of one's weight and health risk risks. More important than BMI, in my opinion, is whether any individual has metabolic syndrome. Elevated triglycerides, low levels of so-called good cholesterol, diabetes or prediabetes, high blood pressure or excess liver fat are a better indicator of individual health, as here is where the cardiovascular risk including heart attack really escalates, as does stroke and heart failure. The elevated BMI may prompt this assessment however.
Other Methods for Assessing Body Composition
Skin-fold thickness is another avenue for measuring body fatness, with calipers, or even underwater weighing. Bioelectrical impedance, dual-energy x-ray absorptiometry (DXA), and isotope dilution are other options. None of these are easily accessible though, can be expensive, and typically require trained professionals to utilize. Studies have variable results as well, because these methods can be difficult to standardize among screeners.
Admittedly, we use the RenPho scale which is $25 on Amazon, but we are a small private practice. We encourage our clients to purchase these for their own home as well, and often they share their annual trends with me during their wellness visit. This isn't an exact science at this low cost, but the BMI shouldn't be the gatekeeper for weight loss treatment or even reassure those with so-called normal findings. Personalizing this evaluation is our goal and in our practice, this includes evaluating trauma, the health of one's nervous system, metabolic factors and epigenetics.
Body weight can lead to stigma and bias. It's complex, but know that the American Medical Association voted to adopt a new policy that moves away from using BMI alone when assessing whether a patient is at a healthy weight. Our practice evaluates weight and height among a plethora of other factors. Connect if you'd like to talk more about weight loss.