Everyone knows that carrying extra body fat is a potential time bomb by increasing the risks of getting heart diseases, stroke and certain types of cancers. These are potential killer diseases. By keeping your body fat down, these diseases may be avoided and even prevented.

One of the most popular methods of measuring whether one is overweight is by using the Body Mass Index or BMI calculation. The formula for calculating BMI is:-

• Body weight in kilograms (pounds) divided by height in metres (ft) squared.

The World Health Organization (WHO) recommends that a BMI measurement above 25 indicates that a person is overweight and a BMI measurement over 30 indicates that he is obese.

However, is this calculation accurate? The BMI recommendation by WHO was based on studies done largely on Caucasians. Thus the BMI recommendation by WHO may be an accurate indication of obesity on an average Caucasian. There are now findings to suggest that people of Asian and African origins have a significantly higher percentage of body fat compared to Caucasians although they may look slimmer than their Caucasian counterparts. Therein lays the danger. If you are an Asian or an African, you may look slim but may carry extra body fat of which you are oblivious to.

As a fitness personal trainer, it is not uncommon that when I measure body fat of my Asian clients who do not look fat physically, their body fat ratio are high.

According to Dr Mabel Yap, Deputy Director of the Department of Nutrition, Ministry of Health, Singapore, ethnic differences in BMI values have important public health implications as they imply that cut-off points for obesity should be lower or higher in different ethnic groups. "Lowering the cut-off point from 30 to 27 in Singapore, for example, would double the prevalence of obesity," she said.

In a study, the School of Physical Education of the National Institute of Education, Singapore and Wageningen University of Netherlands found that body built of a person does affect the BMI calculation of various ethnic groups. This result was further confirmed by other studies in Thailand and Indonesia.

As commonly known, BMI calculation is not accurate for muscular people (muscles are heavier than fat) and now, it may also not be accurate across the board for all ethnic groups. For a start, Asians and Africans may want to define their BMI results as being overweight if it is above 23 and obese if above 27.