This blog post is part of a new monthly Nutrition Advice Column. Feel free to submit your questions to [email protected] or complete the form below. 

Question: My doctor is worried about my BMI, but I heard that BMI is not a good measure of my health. What should I do?

Answer: First of all, you are absolutely correct. BMI (body mass index) is NOT a good measure of your health.

Let’s start with a thought experiment – imagine if BMI did not exist. Imagine if there were no categories that labeled your body size. How would you feel about your body? Sit with that for a minute.

Would you feel differently? If yes, then THIS is how you should feel about your body.

BMI in its current usage is utterly flawed and misused. Using your BMI to tell you about your risk for a disease is like saying “Your hair is brown, you must have high cholesterol”. If that sounds absurd to you, good – using BMI to assess your health is similarly laughable.

Quick note: I am about to dive into the nuances of why BMI is flawed because I believe that arming people with knowledge is one of the best ways to make a societal change. But if you want to stay out of the weeds today, feel free to skip to the end where I give practical advice on what to do if your doctor insists on focusing on your BMI.

Now for the weeds…

I can hear many doctors that I have worked with saying, “But larger bodies are associated with chronic health problems.” I hear you and I’ll dive into that more later, but it doesn’t change that BMI was never meant to be used as an indication of health. 

BMI was created by a statistician, Adolphe Quetelet, in the 19th century. He was looking for a way to establish a “normal” man. And yes, I do mean man, not woman. He was a statistician who wanted a simple way to measure the population.

At its birth, BMI was not intended to tell us anything about our disease risk.

In the 21st century, BMI was revived by a physiologist, Ancel Keys, for research. He wanted to analyze “healthy” men. And again, I do mean men, not women. And by men, I mean primarily white men of European descent. This study led to the use of BMI as we know it, despite neither Quetelet nor Keys intending BMI for medical use. 

The current use of BMI is based on white Caucasian men and does not account for differences in gender or ethnicity.

Aside from its history, there are a number of reasons that BMI is a problematic measure of health.

  • The equation is too simplistic. BMI measures only height and weight meaning that it does not account for muscle mass, bone structure, or fat distribution. Disease risk varies GREATLY depending on these factors.
  •  Larger body sizes get pegged for higher health risk despite being healthy. This can lead to weight discrimination and unnecessary and even detrimental attempts at weight loss. I have more to say about this later.
  • Smaller body sizes may have health risks that are overlooked. I had high cholesterol in my early twenties despite a so-called “normal” BMI. Health providers would not have checked my cholesterol until years down the road if I had not insisted. It is possible that disease risk is being overlooked for many people because of the association providers make with BMI and disease risk. 
  • BMI is a driver behind weight stigma. The categories created around BMI of “normal weight”, “overweight”, and “obese” are stigmatizing. These categories impact how we feel about our bodies. Many people leave their doctor’s appointments upset – not because their labs were out of range, but because their BMI falls into a category deemed “unhealthy”. This leaves them feeling like they need to shrink their body for the sake of their health even if, by all other markers, there are no red flags. This may prevent people from seeking preventative care that could be life-saving.
  • The categories listed above are inherently false. These categories are based primarily on data from white Caucasian men. The categories would likely be different if the data included women and different ethnicities.
  • BMI is distracting. Over-emphasis on BMI has increased weight discrimination including hyper-focus on body size. This distracts from ways we might actually be caring for our health.
  • BMI hides the truth about health and body size. Older adults actually live longer and do NOT have increased risk of disease if their weight is higher than the so-called ‘normal weight’ category of BMI. I have more to say about this a little later too.

When you know all of this, you can easily see the insanity of using BMI to tell us what we should think about our health.

The problem is that BMI is fully integrated into health care.

It is plastered throughout the electronic medical record (EMR). BMI is typically printed on the patient’s summary from their health care provider and it often gets flagged in the medical record for the doctor to address.

I used to teach nutrition to residents at a primary care clinic and I saw first-hand how the integration of BMI into the health system made it difficult for doctors to de-emphasize BMI. Many doctors understood that the use of BMI was faulty, but because BMI was flagged in the EMR, it appeared that they were not doing their job if they did not address it with a patient.

In addition, BMI can be used as a diagnosis code for billing. I worked with many patients who wanted to see a dietitian for help with a lifestyle change, but they did not have any billable health conditions so the doctor used BMI as a diagnosis code so that insurance could be charged for the dietitian visits. Using BMI as a diagnosis code can sometimes make both the dietitian and the patient feel like the doctor wants their BMI addressed and can lead to unnecessary emphasis on body size.  

Many health care providers understand the faulty nature of BMI, but have trouble knowing how to replace it.

The American Medical Association (AMA) recognizes the problems with BMI and released a statement noting that:

“[The organization] recognizes issues with using BMI as a measurement due to its historical harm, its use for racist exclusion, and because BMI is based primarily on data collected from previous generations of non-Hispanic white populations.” (and I would add – men, ONLY men).

The AMA is working on educating physicians on the problems with BMI and they are seeking better ways of assessing health risk assessment.

There has been a resulting commission that recommends a variety of methods for assessing body fat rather than BMI and they acknowledge concern for weight stigma and discrimination.

I would add that not only is there concern for weight stigma and discrimination, which alone cause increased risk of chronic disease, there is concern that any emphasis on body size can prompt dieting behaviors. Dieting behaviors often lead to weight gain in the long term, weight cycling, and increased risk of eating disorders. In addition, weight cycling (gaining/losing weight repeatedly) increases risk of chronic disease more than simply staying at a higher weight in the first place.

As I mentioned earlier – what about the link between larger bodies and chronic disease? 

I have two things to say in response.

First, if you look for a connection, you will likely find it. We live in a fatphobic society with research that is done by humans who are likely fatphobic. (We all are – it’s a terrible byproduct of living in our current culture. To root out fatphobia we must do deep, ongoing work within ourselves.)

Because research is done by fatphobic people in a fatphobic world, we may be finding the connections that we believe exist. But this connection between body size and chronic disease is not as clear cut as many people believe.

There is some research now showing that higher BMI’s (including BMI’s in the so-called “obese” categories) may actually be protective for some conditions. For example, people in the “obese” category are less likely than people in the “normal weight” category to have “lung, stomach, colon and esophageal cancer, malignant melanoma, premenopausal breast cancer, chronic bronchitis, tuberculosis, mitral valve prolapse, anemia, type 1 diabetes, premature menopause, and osteoporosis”. This is just the tip of the iceberg in the so-called obesity paradox.

There is much more I could say, but in the interest of time and space, I will summarize for you with this quote –  “Although having a body weight above the ‘healthy weight’ BMI category is said to result in poorer life expectancy, and [increased risk of disease and death], the evidence from the literature does not support this claim [emphasis mine].”  In other words, our long-held beliefs that having a BMI above a so-called “normal weight” is bad for our health, is NOT true. In reality, BMI tells us NOTHING about our individual health.

Second, even if chronic disease and body size are linked, we do not gain much from focusing on body size. Long term weight loss is nearly impossible and we are not biologically evolved for this. There is a reason the human species has survived as long as it has – our bodies protest and protect against weight loss on every level.

My question is – why do we have to focus on body size at all? Why do we need a BMI replacement? 

We know how fraught focusing on body size is due to weight discrimination and the harm of dieting. We know how little control we actually have over our body size. And above all, weight loss is not a behavior change. 

When people say – I want to lose weight –  this is impractical because it is not something you can DO. Even if you change behaviors, you may lose weight and you may not. For example, I had a client who greatly increased his fruit and vegetable intake, never lost a pound, but his blood pressure normalized. So often, it is NOT about numbers on a scale or body size.

I would suggest that we should toss BMI and NOT replace it. 

Now, to answer your actual question – if your doctor is focused on your BMI, what do you do about it?

  • Send your doctor this article. And if they do not want to hear it from a dietitian, tell them to read the research articles and the AMA’s stance in the list below.
  • Use ‘Don’t Weigh Me’ cards at your next doctor’s visit. Buy them here or reach out to [email protected] and we will send you a few complimentary cards. It can be difficult to push back on health care providers. Even something as simple as asking not to be weighed can feel formidable. These cards do the work for you.
  • Ask your doctor to focus on other markers to monitor your health. Here is a list to get started.
    • Blood pressure
    • Lipids (aka cholesterol)
    • Hemoglobin A1c (blood sugar)
    • Liver function tests
  • If any of the above tests are out-of-whack, ask for a dietitian referral. Doctors are incredibly knowledgeable people, but they are not trained in nutrition. Period. This can lead to false and misleading advice that focuses on body size. BUT be sure to find a weight-neutral dietitian – this is important. Look for this information on the dietitian’s website. It is usually pretty clear.
  • Arm yourself with knowledge – Health At Every Size® Health Sheets: This website provides weight-neutral approaches to common health conditions. If you are tired of hearing “lose weight” as a common refrain to every ailment, this info is a great place to start.
  • Consider if you need a new doctor. If you have tried the above approaches and your doctor insists on focusing on weight to your detriment, then I would find a new doctor. I have met many wonderful doctors who take a weight-neutral approach. There is no need to settle.

In summary, BMI is sh*t and we need to stop using it. Full stop. It is harmful, contributes to weight discrimination and distracts from meaningful approaches to caring for our health. We can do better. 

Articles to read if you are still questioning whether BMI and weight loss are important for paying attention to our health:

I would love to hear your thoughts on this topic. Please do not hesitate to get in touch via email at [email protected]. In addition, feel free to reach out if you have a nutrition question that you would like answered in this advice column. All questions are posted anonymously.

If you would like to work directly with a dietitian at Eat Well Collective, feel free to contact us at here or schedule directly here.

Author bio: Kathleen Hahn, MS, RD, LD is a registered and licensed dietitian. She received her Master’s degree in social justice issues in the food system at Oregon Health and Science University and is passionate about understanding the deeper reasons behind why we eat the way that we do and how outside forces impact our food choices. She spent seven years in Oregon working as a clinical dietitian and teaching nutrition to medical residents. She recently moved back to her hometown in Lancaster, Pennsylvania where she works part-time for Eat Well Collective and is raising her 3 year old son and soon-to-be-born daughter. She is passionate about dispelling nutrition misinformation and recognizes the difficulty of following nutrition advice in the real world.