Washington, Nov 19 (IANS) A swelling tide of obesity over the past two decades has set back efforts to cut down the risks of heart disease.

Kami Banks, cardiology research fellow at the University of Texas Southwestern Medical Centre-Dallas (UTSMC-D), is calling on the medical community to put more emphasis on prevention to reverse the obesity trend.

'Lifestyle changes and physical activity are the key,' she said. 'As physicians we need to prescribe prevention -- writing exercise prescriptions and healthy dietary prescriptions just like we prescribe medication.

'Despite focused public health efforts, there is no net improvement in the overall cardiovascular risk factor profile over the past two decades in the US population,' said Banks.

Researchers led by Banks analysed data from the National Health and Nutrition Examination Survey (NHANES) from 1988 to 2006, representing 8,264 adult men and women between the years 20 and 85.

All had complete risk factor profiles of their blood pressure (BP), fasting glucose, low density lipoprotein (LDL or 'bad' cholesterol) and smoking status.

Researchers found that during this time period, the average body mass index (BMI) increased. BMI, a measure of body fatness, is calculated by dividing a person's weight in kilos by height in metres squared.

In the same period, the number of people with optimal (best) BP decreased from 48 percent in NHANES III, 1988-94, to 43 percent in NHANES in 2005-06.

The number with optimal fasting glucose decreased from 67 percent to 58 percent. Both BP and blood glucose are closely linked to obesity and these adverse trends track with the change in body weight, said an university statement.

These findings were presented at the American Heart Association's Scientific Sessions 2009.