Why This Functional Medicine Expert Uses Immunity (Not BMI) To Determine A Healthy Weight

I'd like to flip the script on our conversations around weight. Instead of counting calories and focusing so much energy on a specific number on a scale, as a functional medicine expert, I'd like us to get smarter about healthy and unhealthy forms of body weight.

To start, it's important to acknowledge that weight itself is just adipose tissue—it's neither good nor bad. Different people can carry different amounts of weight and still be quite healthy. If we can think about healthy weight in this way rather than fixating on arbitrary number, good things will happen. I think we'll see less guilt and shame in our society and more equitable treatment of people despite their socioeconomic status. To put this into practice, I've got a few tips and tricks to suggest below, but it all starts with BMI.

Weight is such a loaded topic across society, and our health care system is no exception. Get a certain BMI number at your next checkup, then all sorts of new conversations and health care costs—from more tests to prescription drugs—can ensue.

However, there is a growing body of scientific literature—and cultural understanding—that BMI is not just an inadequate measure of health, it's also a big part of the structural racism that adversely affects certain communities more than others. 

The BMI standard was developed for an idealized Caucasian male, and the thresholds remain rather oblivious to important discrepancies warranted by gender and ethnicity. For example, there is evidence that Asian individuals hold on to visceral fat around the belly more1 and can thus experience poor health outcomes from excess weight at lower BMIs. And Black women seem to handle much higher BMIs without the metabolic dysfunction that the averages would suggest. 

Not to mention the non-racial flaws. Does a pound of lean muscle affect health the same as a pound of visceral fat? Of course not, but an athlete with greater bone density and muscle mass can easily register a high BMI. Same goes for pregnant and nursing women. 

You get my point. You are not a number, and a healthy weight depends on so much more than your scale. It's hurtful to reduce personal health to a number that takes no account of your behaviors and the socioeconomic pressures that play major roles in so many people's lives. I'm talking about chronic stress and economic inequality. I'm talking about living in food deserts with polluted air and water.

These socioeconomic determinants of health—everything from education and housing to employment, criminal justice, and access to health care—matter, and our reliance on BMI as an easy shorthand for health only furthers the structural racism present in our current medicine.

So how should we think about weight? Research has shown that the health problems that come from being overweight don't arise because we simply accumulate more fat cells. It's the health of those fat cells—specifically, the immune health—that really matters.

We know that people can be overweight but metabolically healthy or have a normal weight but poor metabolic health. Why? Because the immune system plays a big role in whether our fat cells are healthy and happy or angry and damaging to the rest of our bodies. When immune cells called macrophages get activated to an inflammatory state, our fat cells start to create molecules that further promote inflammation. Think of your immune system as the switch that can turn healthy weight into unhealthy weight.

Don't get me wrong. I love a good health metric, and BMI is so prevalent because it's simple, inexpensive, and noninvasive. Unfortunately, it's not all that useful, and our reliance on it perpetuates major social and racial injustices latent in our health care system. 

Rather than BMI, I'd like to offer three alternative ideas to help you connect the dots between your weight and your health. These are ways to harness your body's complementary systems to make friends with your weight and stop obsessing about any single number:

Research shows that when fat cells start getting inflamed, we start experiencing poor health. This means maintaining immune balance and keeping inflammation in check is key to maintaining a healthy weight. The Mediterranean diet is a big winner here, so eat more foods rich in plant nutrients and healthy fats. For more on immune balance, learn about a process called immuno-rejuvenation. It's the reason I started my new company, Big Bold Health.

The gut is a major gateway to the health of our entire bodies. This is especially true as it relates to our fat cells. Everything from your gut microbiome to the integrity of your gut wall may influence your fat cells, so paying attention to gut wellness is key. A good balance of prebiotics and probiotics can really help here.

Hormones like insulin, ghrelin, and leptin are big players when it comes to fat cells, as are a number of lesser-known hormones like GLP-1 and GIP. Maintaining the right balance of these signals may strongly determine whether our fat cells are healthy or unhealthy, as well as our overall weight. Bitter foods like Himalayan tartary buckwheat are a great way to improve this signaling. (More on that unique ingredient here.)

It's so important that the story around weight gets past BMI. We need to start thinking about the ways in which fat cells become polarized toward an unhealthy state by unexpected players like your immune system, your microbiome, and endocrine signals. It's a more complex conversation than BMI, but it's the only way to think about weight inside the larger story—the one that really matters—of overall health and social justice.