Don’t throw your BMI charts out yet, but a new study suggests that your waist-to-hip ratio (WHR) may be a better indicator of your health risk.
BMI (body mass index) charts have been used for decades to assess a person’s weight relative to their overall body size (as measured by their height). In general, high BMIs (above 25) indicate higher health risks. However, according to Salim Yusuf, the lead author on the new study, “BMI is a very weak predictor of the risk of heart attack. Measuring the girth of the waist and the girth of the hip is far more powerful.”
The problem with BMI is its failure to account for where a person carries his or her weight. Though the reasons are not exactly clear, a number of studies show that weight carried around the waist is more dangerous than weight carried at the hips. This may be because waist-level fat surrounds the internal organs and impinges on their operation.
The WHR measurement directly addresses this concern by dividing a person’s narrowest waist measurement by her or his widest hip measurement. If your waist is smaller than you’re your hips, your WHR will be below 1.0.
Earlier studies indicate that WHRs greater than 1.0 for men or 0.8 for women are associated with higher risk of diabetes and hypertension (high blood pressure). The new study suggests that WHRs above 0.95 for men or 0.8 for women indicate a heightened risk of heart attack.
However, in a commentary published alongside the new study, other scientists urged caution in adopting WHR because, as yet, no one has offered an adequate explanation for why a higher WHR would foster a higher risk of heart attack. After all, fat around the waist does not surround the heart, so it is not clear why a WHR would be a better indicator of heart attack risk than BMI. Until this conundrum is explained, the critics suggest doctors resist the temptation to rely solely on WHRs. Rather, health care providers should make an overall assessment of a patient’s health and weight using all assessment tools available, including both BMI and WHR.
According to the National Institute of Diabetes and Digestive and Kidney Disease, “However defined, overweight and obesity contribute to the development of a number of debilitating diseases, including arthritis, heart disease and diabetes.” A healthy diet and consistent exercise will lower health risks for most people.