A new study supports body mass index (BMI) as a useful tool for assessing obesity and health. A simple measure based on weight and height, BMI is widely used to assess whether a person is at a healthy weight. But its reliability as a health measure is often criticized because it doesn't differentiate between fat and muscle and doesn't tell us where body fat is stored.
Using body scans of 2,840 youths, ages 10 and 18, the researchers examined BMI findings against more detailed measures of fat. They studied the effects of total fat, along with fat in the trunk, arms and legs, on 230 different properties relevant to metabolism and future heart disease risk, such as cholesterol and blood pressure. These effects were compared to those observed using BMI as a measure.
The study found that higher total fat at ages 10 and 18 was associated with harmful levels of cardiometabolic properties such as higher blood pressure and unfavorable cholesterol and inflammatory profiles at age 18.
Effects appeared to worsen over time and were driven most by stored and gained fat in the trunk, although gains in leg fat also seemed harmful. Having more lean mass (rated here as something in the body that isn't fat or bone) had less of an impact on traits and didn't seem to protect against carrying more fat. A higher BMI showed similar effects to a higher total and trunk fat, indicating a close overlap between these measures.
