London, March 17 (Reuters): Medical experts called for a new assessment of how weight-related health risks in Asians are measured which could push up the number of overweight and obese people worldwide to 1.7 billion.

The new figure, which would be 50 per cent higher than current estimate is based on recommendations to lower the threshold for Asians because of their special vulnerability to weight-related disorders.

Professor Philip James, the chairman of the London-based International Obesity TaskForce, said the global standard for measuring overweight/obesity, the Body Mass Index (BMI), is based on western criteria and needs to be adjusted for Asians.

“The point of reducing the values is that it will be an altering point which you give to both the public and doctors,” James said in an interview.

The BMI is calculated by dividing weight in kilograms by height in metres squared. In the west a BMI of 23-24 is normal.

Health experts have suggested a lower BMI scale for Asians because of evidence showing their risk of obesity-related diseases such as high blood pressure, abnormal cholesterol and developing diabetes rises if their BMI is more than 23.

By lowering the threshold doctors will become aware of potential risks and will be more likely to advise patients to take measures to reduce their weight.

“There is a wide spectrum of risk factors related to obesity, which when viewed as a whole, have a tremendous impact on health,” said James.

Obesity is caused by the body’s inability to balance energy intake and energy expenditure. People eat too much and do not exercise enough.

A BMI of more than 30 indicates obesity but where the excess fat is accumulating is also important. Abdominal obesity, the accumulation of fat in the stomach area, is a problem in Asia and poses more health risks than fat in the thighs and legs.

So an individual can be quite compact but still suffer the weight-related health risks if all of the fat is centred on the abdomen, the classic pot belly.