While body mass index takes into account height and weight rather than fat, it’s still a valid way to screen for heart risks, based on an English study of nearly 3,000 young adults published in the Journal of the American College of Cardiology.
Known as the ALSPAC study (Avon Longitudinal Study of Parents and Children), this study tracked the health of 2,840 children from birth through age 18. As part of the study, participants had their health, height and weight regularly measured, in addition to undergoing X-ray imaging at ages 10 and 18 to assess fat content.
The goal of the recent analysis was to see how body mass index and fat content relate, especially in regard to heart health.
Body mass index (BMI) is a ratio of height to weight, which helps determine whether patients are underweight, normal, overweight or obese. BMI has been criticized for not including fat in its calculations, which we know has a big impact on heart health. Many worry that BMI may be too simple of a tool to accurately assess health.
However, results of the ALSPAC study confirm that BMI remains useful for evaluating cardiovascular health in children and young adults.
Over the course of the study, researchers tracked 230 markers of heart health in participants, such as blood pressure, cholesterol, blood sugar and inflammation. They found that increases in BMI and fat between ages 10 and 18 resulted in poorer markers of heart health. Overall, these associations between weight and heart health were similar, even after taking into account factors like physical activity.
However, authors note that the association between increased fat content and cardiovascular risk was stronger than that of BMI. They also found that fat in the midsection appears far more harmful than fat in the legs or arms.
The take-home message then, according to authors, is that fat is the driving factor behind increased heart risks. While BMI doesn’t consider fat in its calculations, it’s a useful tool that mirrors the results of fat testing—tests that are far more involved and costly than simply calculating BMI.
So what does this mean for patients? Experts also note that based on findings, gaining fat in any area is not good for health, especially in the first two decades of life. Children who are overweight or obese have much higher risk for health problems later in life. Therefore, BMI remains an important tool for screening for children at increased cardiovascular risk and hopefully motivating lifestyle change to promote better health.
Read the article in the Journal of the American College of Cardiology.