Body mass index, or BMI, has been the standard used to gain a better understanding of one's health. This number takes into consideration the weight and height of a person. New research suggests that BMI is no longer an effective measure for assessing health and disease risk. In this article, we take a closer look at a recent study that found body fat percentage to be a superior measurement in predicting mortality. 

The Limitations of Body Mass Index

Researchers have long known that body weight has a direct impact on health. People who are obese tend to have a significantly higher risk of developing chronic diseases, such as type 2 diabetes, cardiovascular conditions, and others. These conditions affect longevity and can lead to premature mortality. 

As a result, BMI has become a globally accepted measure, providing an overview of a person’s overall health. A BMI over 25, for example, puts a person in the overweight category. When a person's BMI reaches 30, it can indicate obesity. 

The body mass index does hold some potential, but its limitations have been known for a long time. It focuses solely on total body weight and height. BMI does not account for factors like fat, bone, and lean mass, which is why many experts are starting to recommend alternative options for getting a better idea of a person’s health risks. 

Study Finds Body Fat Percentage is a Superior Measurement

A group of researchers sought to determine the effectiveness of BMI as a predictor of mortality compared to measuring body fat percentage. The study’s results were published in the Annals of Family Medicine and provide a detailed overview of the findings. 

The researchers focused on a 15-year mortality risk. The participants in the study ranged in age from 20 to 49.

Researchers established a set of metrics before initiating the study. This gave them universal criteria for both body fat percentage and BMI.

Healthy BMI was classified as 18.5 to 24.9. A BMI of 25 or higher would put the individual in either the overweight or obese categories, depending on the specific number.

For body fat percentage, there were criteria for both men and women. In men, an unhealthy body fat percentage is defined as being over 27%. For women, the number was 44%. Waist circumference was also used as a metric. Women with a waist circumference higher than 35 inches were considered unhealthy, and for men, this measurement was 40 inches.

The researchers found that both body fat percentage and waist circumference had the biggest impact on all-cause mortality. In addition to this finding, the researchers also noted that there wasn’t a significant relationship between BMI and all-cause mortality. The only major association they could identify using BMI was with cardiovascular disease mortality. 

Measuring Body Fat Percentage

While BMI takes just height and weight, measuring body fat percentage is a bit more complex. However, as technology continues to advance, tools that allow individuals to gain a better understanding of their body composition are becoming increasingly accessible. 

DEXA scans have shown particular promise in helping individuals understand their body fat percentage and how it compares to their lean and bone mass. This provides a more detailed approach to help an individual gauge the amount of fat accumulated in their body, which holds greater promise in understanding all-cause mortality risk. 

DEXA scans are non-invasive and rather quick. They involve lying down while a machine takes images of the body to create an image showcasing the distribution of fat, bone, and muscle tissue. 

Conclusion

While many people rely on BMI to determine health risks, new research suggests that body fat percentage is a more accurate indicator of health risks. It provides a view of the total fat accumulated in the body, rather than presenting a collective number that accounts for total body mass. Tools like DEXA scans can help individuals gain insight into their fat mass and track their progress toward weight loss and health goals. 

References

https://www.cdc.gov/bmi/adult-calculator/index.html

https://www.annfammed.org/content/early/2025/06/23/afm.240330

https://www.radiologyinfo.org/en/info/dexa