The importance of using the body mass index

Canadians spend billions each year on prescription diet drugs, weight-loss surgery, diet programs, weight-loss supplements, health clubs, diet drinks and artificial sweeteners ― though many claims for these weight-loss methods are exaggerated. Before potentially wasting your money, you should use the body mass index (BMI) to get some perspective on your weight.

Prescription drugs, which usually suppress appetite or block fat absorption, tend to produce only modest weight loss, while weight-loss surgery is sometimes risky.

Researchers are testing the potential of several hormones to curb appetite. They're also looking at ways to subdue "ghrelin," the so-called hunger hormone.

However, there is not yet any commercially available weight-loss miracle drug.

• Is your weight in the danger zone? One of the most popular measurements today is BMI (body mass index), which takes into account both your weight and height.
• Many websites and health reference books have tables to help you find your number but, if you have a calculator, here's how to determine your precise BMI.
• It's a useful number to know, as most doctors, other health experts and even insurance companies use it to gauge the healthiness of your weight.

To find your BMI number, take:

• Your weight in kilograms (1 kg = 2.2 lb), and
• Your height in metres and square it (m2),

and then

• Divide your weight by your height in m2.

FOR EXAMPLE, if you weigh 70 kg and are 1.71 m tall, your BMI is 24:

• 70 kg
• 1.71 x 1.71 = 2.92 m2
• 70 ÷ 2.92 = 24 (23.97 to be exact!)

For adults aged 20 and older, BMI rankings fall into the following categories.

• A number of 20 to 25 is considered "Normal."
• A number of 25 to 30 is considered "Overweight."
• A number over 30  is considered "Obese."
• And a number that's over 40 is considered "Extremely obese."

It is important to remember, however, that BMI is a measurement tool that was developed over 200 years ago. Back then we knew a lot less about human health and physiology than we do today.

For example, the BMI measures only take weight and height into consideration. But things like muscle density or body fat percentage are also factors when it comes to figuring out if you're "normal," "overweight," or "obese."

In fact, since muscle weighs more than fat, many Olympic athletes are considered "overweight" by BMI standards.

Nonetheless, using the body mass index can give you a quick sense of the healthiness of your current weight (and maybe some perspective amidst all the hype of the weight-loss industry).