Weight: why is a healthy weight important?
Overweight people are more likely to have heart disease, diabetes, heartburn or gastric reflux, and gallstones than those who are within a ‘normal’ weight range. In very obese people breathing may be very difficult, particularly at night when sleeping. Reducing weight to reach a healthy weight range reduces most of these risks.
Life expectancy is generally reduced in obese people. Maintaining a healthy weight also makes exercise and movement easier. Exercise is also important in maintaining a healthy body and reducing the risks of some diseases.
Body mass index
Weight loss is extremely important if you have been defined medically as being obese. This is when your body mass index, or BMI, is greater than 30 if you are of European origin, or greater than 32 if you are from the Pacific Islands. The BMI is calculated as your weight (in kilograms) divided by your height (in metres) squared, i.e. kg/m2. To do this easily, you should take your weight (in kilograms), divide by your height (in metres) and then divide by your height again.
A BMI of 19-25 kg/m2 is a healthy body weight. Weight loss is strongly recommended if you have a BMI of more than 27 kg/m2, and preferably you should have a BMI less than 25 kg/m2. However, it is usually not healthy to have a BMI less than 19 kg/m2. Being underweight is not healthy, particularly if you become obsessed with being very thin.
The advantage of using the BMI as an ideal measure of your weight is that it allows for your height as well as your actual weight. However, these figures are not absolute cut off values as people with a high muscle mass (such as body builders) may have a higher BMI but may not be fat.
Specific conditions
Weight control is very important if you have diabetes. It is also important if you have osteoarthritis, because weight increases the stress on the joints. People with any heart conditions should also try to maintain a healthy BMI of about 25 kg/m2 or less.
Children
While children should eat healthy food, they are not small adults. A growing child’s diet requires a different proportion of fats to carbohydrates to fibre compared with an adult’s diet. Children with weight problems should be reviewed by a doctor or dietitian.
Last Reviewed: 11 June 2002
