BMI is usually used to measure the health risks linked to obesity because of its easy calculation and interpretation. Typically, as BMI goes up, the risk of health problems can increase. However, some people may have a “normal” BMI (between 18.5 and 24.9 kg/m) but still carry a high amount of body fat, particularly around the abdomen.
So, although BMI can screen for obesity, it can’t measure body fat distribution. Body fat distribution may indicate someone’s risk of heart related conditions, which they may be unaware of. Additionally, the link between BMI and cardiovascular risk factors can also change based on ethnicity. For example, Asian populations tend to see an increased risk of heart related conditions at a lower BMI than Caucasian populations.
To address possible limitations to the BMI, and to help give a broader understanding of the risks associated with obesity, the Waist-to-Height Ratio (WHtR) can be used. This calculated ratio focuses on the relationship between waist circumference and height to identify cardiovascular risk related to obesity. By dividing your waist measurement by your height, this ratio provides insights into how fat is distributed throughout the body—particularly visceral (abdominal) fat, which may lead to serious health conditions like heart disease, diabetes and hypertension (high blood pressure).