Please roll cursor over

topic headings and select


 


 


 

Am I Overweight?

A Guide to Measuring Overweight and Obesity


For those individuals who are interested in exactly how body weight in relation to health status can be assessed and how to recognize when to take action, here is a summary of some of the latest scientific thinking and some practical tips for action. However, generalised advice can never be a substitute for personalised medical review and treatment, and those readers with any serious health concerns are strongly advised to consult a qualified medical practitioner.

The Asia Phenomenon
The risk of developing chronic ill-health appears to increase amongst many Asian populations at lower levels of body weight, than in Caucasian populations.  Experts have identified some physical characteristics which are relatively common in Asian populations, and which are contributing to this phenomenon.  In particular, adults with excess fat concentrated around the abdominal area, and/or who were under-nourished in very early life and subsequently gained excess body fat very rapidly as infants (the so-called 'Barker effect') and/or who lead very sedentary lives seem to be much more likely to suffer from ill health and disease associated with overweight and obesity. (1)

Vital Statistics
 Here are some recommended methods for assessing individual health status, using individual vital statistics and some simple mathematics:

BMI
 The global standard for classification of body weight as normal, underweight, overweight or obese is Body Mass Index (BMI). BMI is calculated by dividing a person's weight in kilograms by their height in metres squared. Until recently, the same classification standards have been used in all parts of the world, to assess and categorise body weight: A BMI of 18.5 to 25 is traditionally classified as normal, 25 to 30 as overweight  and is associated with increased risk of developing weight-related disorders, and above 30 is classified as obese and at high risk of developing weight-related illness.

In recent years, experts, have observed that weight-related disorders are more common in some Asians ethnic groups at BMI levels above 23. An expert group of the WHO has therefore recommended a lower BMI scale for Asians: 18.5-23  for increasing but relatively low risk of developing weight- related ill-health; 23-27.5  for increased risk; and 27.5 or more signals high risk. (2)

A disadvantage of the BMI scale however, is that it may overestimate body fat in athletes and others, such as Pacific Island ethnic groups, who have a muscular build. BMI may also underestimate body fat in older persons and others who have lost muscle mass. Hence, experts recommend the use of BMI combined with waist circumference or/and waist-to-hip ratio for a more accurate assessment (3).

 

Weight in Kilograms

BMI Formula =
 

(Height in Metres) x (Height in Metres)


Waist Circumference
 Waist circumference  is measured around the narrowest point between ribs and hips when viewed from the front after exhaling. Waist circumference, is a measure of abdominal fat and a good indicator of health status, even when the BMI calculation falls within the range classified as normal. Waist measurements of over 102 cm (40 inches) in men and over 88 cm (35 inches) in women were set as the global thresholds for determining increased likelihood of developing weight-related disorders.


More recently, lower thresholds for waist circumference have been recommended for Asian populations. The Working Group on Obesity in China organized a review of the data on the relationship between BMI, waist circumference and risk factors of related chronic diseases.  Based on this review of all the evidence collected to date, the Working Group recommended waist circumferences of over 85 cm for men and over 80 cm for women in China, as the threshold figures for diagnosis of central or abdominal obesity (4).  These figures have not been recommended for the whole of Asia but nevertheless, do provide an alternative scale to the global figures which may not fully take into account the differences in fat distribution and body composition between Caucasian and Asians.


Waist-to-Hip Ratio (WHR)
 Waist-to-hip ratio (WHR) is the ratio of a person's waist circumference to hip circumference. This measurement can be calculated by dividing waist circumference by hip circumference.

WHR, like waist circumference is a tool to assess distribution of body fat. For most people, and perhaps especially Asian populations, abdominal fat causes more health problems than carrying extra weight around their hips or thighs. A WHR of 0.90 or less is considered healthy for men and a ratio of 0.80 or less is considered a sign of good health for women. A waist : hip ratio of 1 or higher signals increased risk of ill health and an indicator that action to shed some body fat from the tummy would be wise (2).

Signals for Action
 Together, these three measures of body size, provide some very useful criteria against which to assess body weight and determine action targets, to maintain, lose weight or recognize and halt gradual weight gain. It seems for Asians in particular; an assessment not just of body weight, but also abdominal fatness is a wise and relatively simple health check.

Regardless of whether individual targets are to maintain weight or lose weight, the guidelines to maximize individual chances for a long and healthy life are the same: Aim to gradually establish a healthful lifestyle which fits in with other commitments of daily life, and is based on a low-fat, varied and balanced diet, combined with regular physical activity. The yo-yo effect of repeated weight loss and weight gain, which occurs in those who follow a  repeated pattern of dieting to lose weight rapidly, but then gradually regain the weight lost when they return to old eating habits, brings its own health risks and makes long term weight control increasingly more difficult.

Thirty to sixty minutes every day of moderate to vigorous physical activity such as brisk walking, or swimming, helps in weight maintenance and weight loss, and regardless of body  weight, massively reduces individual risk of developing heart disease, strokes and other chronic disease because of the benefits it brings to cardiovascular health. An additional incentive to exercise may come from a study reported in the Journal of the American Medical Association which found that regular exercise reduced "intra-abdominal" fat, and therefore trimmed waistlines even in those who lost no weight (4). Regular exercise also brings many other benefits, such as improved sleep quality and psychological well being.

Experts also stress that maintaining a healthy weight needs to be a lifetime goal. The World Health Organisation recommends that adults should aim to gain no more than 5 kilogrammes throughout adult life. The first steps towards this goal could be to invest in some simple weight scales, a tape measure and perhaps a calculator - the only equipment needed for individuals to establish lifelong oversight of healthful body weight.

- References
 

 

Copyright © 2004 Asian Food Information Centre (AFIC)
Disclaimer