Scientists do away with body mass index A man walks on the National Mall in Washington DC on August 13, 2010. Obesity in the United States has increased to 2.4 million obese Americans since 2007, according to a report released this week by the Centers for Disease Control and Prevention (CDC). LONDON, May 12 (UPI) -- British researchers say people concerned about heart disease and diabetes should watch their height-to-waist ratio rather than the body mass index. A team of British scientists found people should keep their waist measurement to half of their height, The Daily Telegraph reported. In a study of 300,000 people, the team found this ratio was a better predictor of high blood pressure, diabetes and cardiovascular problems than the body mass index, which is calculated by dividing people's weight by their height. "Keeping your waist circumference to less than half your height can help increase life expectancy for every person in the world," said Dr. Margaret Ashwell, who headed the study. Ashwell presented the study Saturday at the European Congress on Obesity in Lyon, France. While the body mass index was a useful indicator, Ashwell said, it does not take distribution of fat throughout the body into account. Ashwell said the waist-to-height ratio should be considered as a screening tool.