Looking for Disease in the BMI Crystal Ball

It is already known that being overweight or obese can increase the risk of diabetes and heart disease.

New research shows that it is possible to predict a teenager's risk by looking at their Body Mass Index (BMI) - a measure of body fat based on height and weight.

Researchers found that they may be able to predict a teenager's risk of type 2 diabetes and heart disease in adulthood, even if that teen has a normal BMI (a score less than 25).

Researchers only need to see a small rise in a teen's BMI to predict a noteworthy increase in risk for these diseases.

Changes in BMI indicates diabetes and heart disease later in life.

From a study that followed about 37,000 teenagers for 17 years, researchers found that a one unit rise in BMI was linked to a 10 percent increased risk of type 2 diabetes in young adulthood.

For every one unit increase in BMI, there was a 12 percent increased risk for heart disease.

While BMI at age 17 can give researchers an idea of a person's risk for type 2 diabetes later in life, BMI in both teenage years and adult years can signal risk of heart disease.

According to Dr. Amir Tirosh, from Brigham and Women's Hospital and Harvard Medical School, these results show that a teen with a relatively high BMI can almost eliminate his or her risk of diabetes by becoming a lean adult.

However, a heavier teen who loses weight as an adult still has a significant risk of heart disease.

In other words, says Professor Iris Shai of Ben-Gurion University, "Heart disease appears to have a longer 'memory' for BMI than diabetes, so the history of a person's BMI should be part of medical risk assessment."