BMI Calculator

The BMI (body mass index) is a measure of whether you're a healthy weightfor your height. Utilize the BMI calculator to check whether your parents are healthy.

For children, go to Weight Concern's Child page and the young people's Body Mass Index (BMI) Calculator. Imperial

This calculator is only to be utilized in the case of adult (pregnant or lactating mothers should not be relying upon these BMI readings) And no action should be made based on its results apart from consulting an appropriately qualified professional such as a physician.

The calculator will give you an insight into the way your weight compares with common values. Body Mass Index (or BMI) is calculated by taking the weight of your body (in kilograms) subtracted by the size of the square (in metres) or BMI = Kg/M2.

Is Body Mass Index reliable?

Your BMI, or Body Mass Index, is a measure of your weight as a percentage of your height. An accurate assessment of obesity is important, as being obese or overweight significantly increases the risk of contracting a number of medical conditions like type 2 diabetes, heart disease and cancer. With the rate of weight gain or obesity increase The spotlight has fallen to BMI and its flaws as a measure of optimal weight for an individual instead of a whole population of people for whom "averages" apply.

"Some people naturally have a larger frame than others. But this causes quite a small variation in weight and is accounted for in the range of healthy BMI. There is really no such thing as someone who is big-boned. " Dr Jan Sambrook, How to lose weight in a healthy way

For most adult people, BMI is a great estimate of your weight-related health risk. If your BMI is higher than 35, you are certain to put your health at risk regardless of the reasons below. There are however some situations where BMI could be over or underestimating these risks in the 25-35 BMI range. The main ones are:

Children

Your physician or health visitor can provide advice on the position of your child on the "centile charts" which are used to calculate the weights that are healthy for children.

Pregnant women

Usual BMI estimates do not apply if you're pregnant.

If you're very muscular

BMI is based on the assumption that you are carrying an average amount of body fat such as 'intra-abdominal' fat - fat deep inside your stomach cavity instead of under your skin. In fact, abdominal fat is more closely connected to risk of type 2 heart disease and diabetes than skin fat.

If you are very muscular then your body fat could be lower than what is predicted by your BMI. But, this is only applicable to people who do intense exercise much more than average.

If you're of Asian origin

People of Asian origin are prone to accumulating intra-abdominal fat (fat deep within your stomach cavity , rather than under your skin) at lower BMIs than those who are of Caucasian origin. People who exhibit this pattern with weight gains are referred to as 'apples' rather than "pears" as per their body outline. That means that their risk of health begin to increase at lower BMI due to the fact that abdominal fat is directly connected to the development of heart disease and kind 2 diabetes.

The World Health Organisation has looked at the evidence, and because of the wide range of Asian populations and the different ethnic groups, it hasn't made any changes to the cut-off points. However, it recommends that for purposes of public health some Asian groups should be classified as overweight If their BMI is between 22-25 and obese if they have BMIs between 26 and 31.

People who are older (over 65, or possibly 60)

Because muscle mass tends decrease and body fat tends to increase with age However, BMI isn't an accurate indicator of body fat if you're older than 60.

Alternative estimates of weight-related health dangers

If you feel BMI may not accurately indicate whether you're obese or overweight, measuring your abdominal circumference, waist, or waist ratio can provide an estimate that is more accurate.

Waist circumference

You can measure your waist circumference approximately halfway between the lower part of your ribcage to high-top of your hip bones, using a tape measure that is in line with the floor. The person breathing out must be present when you measure. Male

• Health risk increased - > 94cm
• High risk of health - > 102cm

Female

• Risk of increased health - >80cm
• High health risk - >=88cm

The ratio of waist to hip

To assess your waist-to- hip ratio, take a measurement of you waist circumference (as above), and your hip measurement at the widest portion on your hips. Divide your abdominal circumference by your hip measurement to calculate an approximate ratio.

• In women, a waist-to- hip ratio greater then 0.85 is associated with higher than average risk.
• For males the waist-to-hip ratio that is greater that 1.00 is associated with a higher than average risk.

Ratio of waist to height

A recent study that compared BMI and waist circumference with hip to waist ratio and waist to height ratio found that the most reliable method of predicting your whole-body fat percentage was to look at the waist-height ratio.

Measure your waist circumference as above, and then divide it by your height . clearly both measurements must soit be measured in imperial (inches) or in metric (cm).

The definition of obesity for the whole body is by a waist-height ratio of:

• 0.53 and more men
• 0.54 plus for females

Abdominal weight gain is measured by a waist-height ratio of 0.59 or more.

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