This text is taken from Joanna's book "Drop A Size for Life".

> Assessing your body mass index (BMI)
> BMI categories
> Waist circumference
> Taking your girth measurements
> How to measure

ASSESSING YOUR BODY MASS INDEX (BMI)
BMI is a simple way of assessing your body weight status. It's not foolproof, however, as it does not distinguish between fat and muscle. It's also not a good measure of progress as you get fitter, as increased muscle mass may actually make you heavier rather than lighter, although you will be substantially fitter and trimmer and slipping into a smaller clothes size.

Use the formula below to determine your BMI and then check this against BMI categories to see whether you are already a healthy body weight or if you have a more significant amount of body fat to lose.

To obtain your BMI, measure your weight in kilograms and your height in metres and then divide your weight by your height squared: W/H² = BMI.

For example, if you weigh 63kg and are 1.70m tall, you multiply 1.7 by 1.7 to give you 2.89, then divide 63 by 2.89. This gives a BMI of 21.79, which, as you can see from the categories shown below, would put you within the normal weight range.

BMI CATEGORIES
Underweight = under 20
Normal weight = 20-24.9
Overweight = 25-29.9
Obese = 30+

(If you want to make life easy, you can calculate your BMI automatically without having to do the maths by clicking either of the buttons directly below)




WAIST CIRCUMFERENCE
Although BMI has been widely used since the 1980s to estimate body shape change and the risk of various obesity-related diseases, using the waist circumference measurement is simpler and has been shown to indicate obesity-related risks just as well as BMI. Developed by an expert panel on obesity and health risks, the waist circumference method of indicating health risk classifies a healthy waist circumference as being below 102cm/40in for men and 88cm/34 for women.

As well as being simple, the waist circumference measurement also gives a more accurate picture of an individual's body fat distribution. And since the Drop a Size for Life plan is concerned not solely with measuring weight on the scales but more with clothes size, girth measurements are the best way to monitor your progress as you follow this plan.

TAKING YOUR GIRTH MEASUREMENTS
The charts below shows the usual measurements that are taken - if you wish you could use this chart if you decide to start the "Drop a Size for Life" plan. The body fat measurement is not essential but it is helpful. Body fat can be measured using skin fold calipers or, more conveniently, using a body fat monitor - these are similar to bathroom scales but they determine your percentage body fat, giving a truer idea of what is going on in your body.

HOW TO MEASURE
Chest - measure with tape flat across the nipple line
Waist - measure around the narrowest part of your midrift (for men, pull your tummy in for the first reading and let it go for the second)
Navel - measure around the midrift directly over the belly button
Hips - measure across the top of the buttock cheeks
Thighs - stand with feet together, measure 20cm/8in up from the top of your kneecap and take a circumference measurement of your thighs.

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