What is Overweight and Obesity?

Posted on 17. Sep, 2009 by yuri in Weight Loss

Being overweight and/or obese is simply an over-accumulation of fat in your body.

There are many potential causes for obesity and being overweight including poor diet, lack of exercise, and more.

In this post we’re going to look at how you can measure your body composition and whether you’re overweight or obese using 3 different measurements:

  • BMI
  • Hip to Waist Ratio
  • Body Fat Percentage

Body Mass Index (or BMI)

The guidelines for what is considered normal weight, overweight and obesity has been classified by many organizations, including the World Health Organization.

These weight guidelines are based on the Body Mass Index (BMI) – a measurement of your overall weight relative to your height.

The Body Mass Index formula is:

Your weight (in kilos)
divided by
your height (in meters) squared (or kg/m2)

  • A BMI of less than 18.5 is considered underweight.
  • A BMI rating between 18.5 and 24.9 is considered normal.

  • A BMI rating between 25 and 29.9 is considered overweight.

  • A BMI rating of 30 and above is considered obesity.

The problem is using BMI to determine where you stand is that it doesn’t account for the difference between lean and fat tissue. It simply takes your overall weight and uses that.

That becomes an issue for many athletes who, according to the BMI, may be overweight or even obese but in reality just have a larger amount of muscle. 

For instance, a rugby player might have a BMI of 28 (close to obese) yet his body fat is only 12%. 

See the problem?

Waist Circumference and Waist to Hip Ratio

A waist circumference greater than 102 cm in men and 88 cm in women is considered as obese.

Also, a waist-to-hip ratio (the circumference of the waist divided by that of the hips) of greater than 0.9 for men and  greater than 0.85 for women is also a measure of central obesity.

It’s also interesting to note that…

In those with a BMI under 35, abdominal body fat is related to negative health outcomes, regardless of the person’s total body fat.

Intra-abdominal or visceral fat has a particularly strong correlation with cardiovascular disease and that women with abdominal obesity have a cardiovascular risk similar to that of men.

Although these 2 measures are good indicators of being overweight, the best way to find out your true body fatness is by measuring your percentage body fat.

Body Fat Percentage

Body fat percentage is total body fat expressed as a percentage of total body weight.

In general, men with more than 25% body fat and women with more than 33% body fat are obese.

As I mentioned earlier, I’m not a big fan of BMI. However, if you don’t have access to any body fat measurement techniques (described below) you can use the following equation based on your BMI:

Bodyfat% = (1.2 x BMI) + (0.23 x age) − 5.4 − (10.8 x gender)

*where gender is 0 if female and 1 if male

This formula takes into account the fact that body fat percentage is 10 percentage points greater in women than in men for a given BMI.

It also recognizes that your percentage body fat naturally increases as you age even if your weight remains constant.

The results of this formula have an accuracy of about 4%. So take your findings with a grain of salt.

There are many other methods used to determine body fat percentage. Hydrostatic weighing, one of the most accurate methods of body fat calculation, involves weighting a person underwater.

Two other simpler and less accurate methods have been used historically but are now not really recommended, although they are still highly used.

The first is the skinfold test, in which a pinch of skin is precisely measured to determine the thickness of the subcutaneous fat layer.

The other is method is called bioelectrical impedance analysis which uses electrical resistance. Although it is the easiest and less invasive to use, bioelectrical impedance has not been shown to provide an advantage over BMI.

Having worked with thousands of people who have want to lose weight fast, I can tell you that it’s pretty easy to become obsessive about your percent body fat.

At the end of the day, you know if you are overweight or obese. Just look in the mirror. Do your clothes fit? Can you walk up a flight of stairs without collapsing?

Your goal should be live an active healthy life. When you do that your weight will naturally come under control.

=> CLICK HERE if you’re serious about burning fat for good!

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