Although it’s been used for decades, the use of BMI as a health metric is sorely outdated. Here are 3 reasons why it doesn’t measure up.


Determining a healthy weight is a complicated issue. We can observe the variability simply by looking around us – 

We obviously come in many different shapes and sizes. 

Regulation of body weight seems to be a mix of a variety of factors, most notably genetics and environment.

The issue becomes more complicated when we try to use weight to measure health. The way this is done is typically through the Body Mass Index, a weight-to-height ratio, calculated by dividing weight in kilograms by the square of height in meters. 

Interpreting the research we have on BMI and health risk is tricky. As we do so, it’s important to remember that correlation isn’t causation, as the headlines may try to suggest

While we do see that weight is correlated with disease risk, these studies also rarely control for lifestyle factors, socioeconomic status, level of access to resources, and other critical factors. If we aren’t factoring in all the other variables on health, we can’t confidently say that weight is negatively impacting our health – on a population or individual level.

However, BMI is commonly used to classify someone as “normal weight”, “overweight”, or “obese”, which supposedly correlates with morbidity and mortality. Being classified as “overweight” or “obese” based on BMI is seen as a risk factor for the development of several health issues.

But how accurate is that? Does BMI accurately measure fitness or fatness, and does having a higher BMI actually come with greater risks for health concerns or mortality rates? 

There are three distinct drawbacks to using BMI as a measurement of health that has been discussed.

1. BMI was never created for or meant to be used on individuals

It was originally created in the 19th century by a Belgian statistician (not a physician or medical researcher) by the name of Lambert Adolphe Jacques Quetelet who was trying to assess the collective weight of a population (men only). However, it’s easy and quick, which made it more convenient for doctors and insurance companies to adopt and use.

2. BMI is only concerned with height and weight

Other than these two factors, BMI doesn’t account for much else. It doesn’t factor in muscle mass, hydration status or bone density, and therefore isn’t an accurate measurement of fitness or fatness.

3. BMI correlations to morbidity and mortality do not take into account genetics

Dr. Frank Nuttall, a physician and past American Diabetes Association honoree for his work in endocrinology and diabetes, once wrote a critical review of BMI research and why the classifications given by its measurement may be misleading. 

In fact, he found that the lowest death rate “was among those in the ‘overweight’ category, and this was particularly true among the men. There also was a broad range of BMIs over which there was little difference in mortality (BMI of 23.5 to 30).”  Many people were very surprised to learn that the “healthiest” BMI bracket correlates with the “overweight” category.

The truth is, our health is more than just weight and height.

The draw for using BMI to measure health is easy to see — it’s fast, clear-cut and objective. However, a closer look makes it clear that there are other factors to consider and a healthy weight may be more subjective and variable.

Most importantly, while BMI may be correlated with increased health risks, it’s vitally important to remember correlation is not causation. It could be that we are comparing apples to oranges, with other characteristics and variables that aren’t being considered. 

As Amy Herskowitz, a senior consultant for community health care government programs in Canada, once explained on why the Health At Every Size (HAES) model is a better way to approach health than using BMI:

“The HAES paradigm builds on the research showing that social determinants of health: socioeconomic status, equality, equity, social support, and freedom from racism, violence, sexism, poverty, weight stigma, and so on, are the most important contributing causes of health disparities, and yet, they are rarely addressed within medicine or the clinician-patient relationship.” 

As she further emphasizes, “A lack of attention to these issues, combined with an obsessive focus on arbitrary numerical cutoffs that define health and disease, allow capitalist market concerns like profits from drugs, surgeries, diets, and procedures to trump scientific inquiries that establish how to optimize our well-being.”

So what is the best way to determine your health?

It’s the one you maintain effortlessly with healthful, non-restrictive, adequate and flexible food patterns combined with sane amounts of physical activity. 

It’s a weight where you are free of food and exercise preoccupation, and can live life without having to plan around those things.

After all, you’re more than just a number.

Adapted from the original post.

Emily Fonnesbeck, RD, CD, CLT is a Utah-based private practice Registered Dietitian. Instead of creating unnecessary restrictions, Emily focuses on helping individuals become confident and in charge of their own well-being through Intuitive Eating and Mindful Living. She is a strong believer and advocate for helping people become capable individuals who are confident in taking care of themselves.  Make a visit and read more from Emily.