Not Weight, Not BMI: Scientists Say This Number Has A Bigger Effect On Your Health Than You Think

Body mass index (BMI) is a common measurement healthcare professionals assess when evaluating your overall health. It's a simple metric that looks at your body weight compared to your height and allows health professionals to quickly estimate your body fat percentage and risk of health conditions like heart disease, diabetes, and cancer. Even though calculating your BMI may still be of at least some benefit, the author of a 2024 review found evidence that your ZIP code may be an even more predictive number in terms of health outcomes. 

You've probably never had your ZIP code evaluated in your doctor's office, with the exception of your intake forms, but there are many reasons why it may correlate with predictive health outcomes. One of the strongest is a relationship between socioeconomic status and heart disease. According to the World Health Organization (WHO), income levels are related to health, with people with higher income having better access to quality housing, education, social protection, and job opportunities, as well as having a lower risk of illness and death. People in lower socioeconomic neighborhoods often have poorer access to healthcare, which can lead to worse outcomes once they're sick.

Doctors rarely evaluate BMI in isolation any more since it only provides one snapshot of your health without considering your family history, genetic factors, and any habits that might make you more likely to die early. For example, your resting heart rate may help predict your heart health. Considering your ZIP code may help health professionals indirectly evaluate other potential factors such as the air quality, availability of grocery stores with healthy food choices, the walkability of the area, and facilities for physical activities. People moving to areas with high rates of health conditions such as high blood pressure, diabetes, and obesity often experience increased rates of these issues too. These conditions are among the top risk factors for premature cardiovascular-related death such as stroke and heart attacks. 

Additionally, neighborhood-level racial segregation may increase the risk of heart disease due to factors such as poor healthcare access, fewer resources, and historical socioeconomic injustices. For example, black Americans have nearly a three-times higher risk of high blood pressure than white Americans, but research suggests the difference becomes smaller in areas with low racial segregation. Additionally, people living in the United States but born abroad consistently show lower rates of high blood pressure versus people born in the United States.

The geographic location you live in potentially contributes to your overall health. However, it's important to remember that no single metric gives you an entire snapshot of your health profile. Other factors such as your genetics, your diet, and your lifestyle habits also strongly relate to your risk of developing certain health issues.

In 2023, the American Medical Association released a report highlighting some of the concerns of using BMI as a health measurement. They noted that it may be inaccurate at measuring body fat percentage in multiple groups since it was primarily used with a non-Hispanic white population and may not accurately predict body fat percentage in other populations. The report highlighted the importance of using other metrics when evaluating an individual's health.

Your genetics are largely out of your control, and the area that you live in is often at least somewhat out of your control. However, many other aspects of your health may be modifiable. No matter where you live, you can maximize your outcomes by following good lifestyle habits. These habits include regular physical activity, avoiding tobacco products, avoiding smoking, and eating a balanced diet.

As a general rule of thumb, the American Heart Association recommends at least 150 minutes of moderate-intensity physical activity as well as at least two sessions of full-body resistance training per week for adults. You can achieve additional benefits by staying active for at least 300 minutes (five hours) per week. Examples of moderate-intensity physical activity include gardening, dancing, doubles tennis, or brisk walking.