Tuesday, July 13, 2010

AM I FAT?

A common question. There is no general agreement on what constitutes a 'fat' person, so we need to ask a more precise question. We can ask: Am I Obese?
Obesity is often defined by Body Mass Index' [BMI], a metric that is more useful when combined with others [to be discussed later]:


BMI Classification
 < 18.5 underweight
18.5–24.9 normal weight
25.0–29.9 overweight
30.0–34.9 class I obesity
35.0–39.9 class II obesity
≥ 40.0   class III obesity



BMI = weight in kilograms / [height meters]2

BMI = weight in pounds x 703 / [height inches]2

BMI can be misleading, as it takes no account of muscle mass.
For example: Franco Columbu [photo below] in peak condition weighed 185 lbs at 5ft 5inches [BMI 30.7 > class I obesity!].
Franco had virtually Zero body fat. He was a world class body builder and renowned as one of the world's strongest men.
So you can see how BMI sometimes relates poorly to weight condition.

To get a better picture, we can use different metrics to help evaluate  the weight condition.


Waist-hip ratio [WHR] is a good measure of  weight condition, and health risk.  More weight around the waist, compared with weight around the hips, is known to cause greater risk to health.
WHR is easy to measure: > hip girth at the widest part / waist girth at the belly button. 
Male Female Health Risk Based on WHR
0.95 or less0.80 or lessLow Risk
0.96 - 1.00.81 - 0.85Moderate Risk
1.0+0.85+High Risk











Diet Calculator



%PERCENT BODY FAT
In my opinion % body fat and WHR are better metrics for weight condition than is BMI.
Use the above diet calculator to find your % body fat

FEMALE
Age Yrs Underfat Healthy Overweight Obese
20-40 < 21% 21-33% 33-39%  39%+
41-60 < 23% 23-35% 35-40%  40%+
61-79 < 24% 24-36% 36-42%  42%+


 MALE
Age Yrs Underfat Healthy Overweight Obese
20-40 <8% 8-19% 19-25% 25%+
41-60 <11% 11-22% 22-27% 27%+
61-79 <13% 13-25% 25-30% 30%+