Health is not linear for everyone. Many people have skewed perception about health; they think a person who is thin is naturally healthy, while a person who is overweight is inherently unhealthy. A recent study published in the Annals of Family Medicine suggests that BMI, a measure of body fat based on height and weight, is a poor predictor of a person's risk of death. Instead, the study highlights body fat percentage (BF%) as a more effective and easily assessed measurement during routine checkups. Shortcomings of BMI Doctors have traditionally used BMI to check a person's fat, bone, and muscle health, especially since body composition is linked to a higher risk of conditions like type 2 diabetes and heart disease. BMI is calculated by dividing a person's weight by their height squared. While a higher BMI can sometimes suggest a greater chance of developing certain health problems, there's growing evidence that it's an imperfect measure. It doesn't consider important factors like a person's age, biological sex, or how their fat and muscle are distributed. For example, top athletes often have a lot of muscle, which can give them a high BMI. Even though these athletes are very healthy, focusing only on their BMI might incorrectly label them as having obesity. On the other hand, some people with a "normal" BMI might still be at a higher risk for conditions like diabetes, high blood pressure, and fatty liver disease. These individuals are sometimes referred to as having "normal weight obesity" or, in simpler terms, being "skinny fat." Why Body Fat Percentage Might Be Superior With the limitations of BMI in mind, researchers looked into how strongly BMI is connected to the risk of death. They also wanted to see if body fat percentage, which they described as "an easy, reliable, and inexpensive measure," could do a better job of predicting this risk. The research team analyzed health information from thousands of adults. This data included height, weight, waist size, and body fat percentage. They calculated BMI for these individuals and then tracked who passed away over many years. After considering various factors, the scientists made some key discoveries: There was no significant link between having a BMI categorized as obese (meaning a BMI of 25 or higher) and a greater risk of dying from any cause when compared to those with a "healthy" BMI. Body fat percentage, however, provided clear insights into mortality risk. Individuals with a high body fat percentage (27% or more for men and 44% or more for women) were significantly more likely to die from any cause. Waist size was less accurate than body fat percentage but still showed some connection to a higher risk of death. The Future of Health Assessments The study suggests that directly measuring body fat percentage, which is relatively inexpensive and easy to do in a doctor's office, is better at predicting future mortality risk than using BMI. This doesn't mean doctors should stop using BMI entirely. It can still be a simple starting point to help determine if a patient needs to lose weight or gain muscle to prevent chronic diseases. But it should be seen as just that—"an easy first step." Ideally, other measurements should also be taken. The more information doctors have—including BMI, waist size, body fat, blood pressure, and cholesterol—the more complete a picture they'll have of a patient's health. Modern devices can measure body fat percentage quickly, often in under a minute. It's hoped that more doctors will start using body fat percentage measurements, as a direct measure of body fat can be a valuable tool for preventing disease.