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What’s Wrong with BMI?
By Anne Keckler | March 21, 2008
We’ve all heard that we have an obesity epidemic in the United States. It’s true that more and more children, as well as adults, are overweight. But obesity is being defined by BMI, or Body Mass Index. Is this a good indicator of obesity?
I don’t watch TV at home (but I make up for that by spending all my time on the computer), but while I was away I happened to catch a few minutes of some morning news show. The guests were talking about whether it’s possible to be fat and healthy. Rachel, author of The F-Word blog told her story of losing weight, and losing her health along with it. She was trying to attain an “average” BMI, and she ate an 800-calorie diet while exercising for two hours each day just to maintain that BMI once she reached it. Her journey took her from being 300 pounds down to 125 pounds, but in terrible health.
One thing is clear from this: thinner does not necessarily equal healthier! And BMI is a very poor indication of one’s health. As Rachel pointed out, according to some sources Tom Cruise has a BMI of 31, making him officially “obese.” Bodybuilders fall into this range or higher, too.
That’s because BMI doesn’t differentiate between weight from fat and weight from muscle and other lean body tissue! BMI is calculated only from your height and weight, period.
Did you know that you have an average to low BMI and still be overfat? There is a term used by many trainers to describe this: skinnyfat. When someone loses 175 pounds by dieting and doing endurance-style cardio exercise, she will lower her BMI but not necessarily increase her lean body mass.
That’s where resistance exercise comes into play. In order to increase your metabolism and be truly healthy, you need more than just a low weight. You need muscle! You don’t have to look like Arnold, either. Tom Cruise, Brad Pitt, and other leading men tend to be lean but strong. They have a gymnast or swimmer’s look, which most people find attractive.
When setting your fitness goals, ignore BMI. Ignore the number on the scale, for the most part. Set yourself a goal based on bodyfat percentage, and you’ll end up healthier in the end.
As for Rachel, she ended up increasing her calories, thus overcoming an eating disorder she had developed in her quest for an average BMI. She now weighs about 175, if I remember correctly. Unfortunately, I have no idea what she is doing for exercise, nor what her bodyfat percentage is.
For reference, here is a chart of bodyfat percentages. Remember that your own ideal body fat will depend on your body type, health, and goals.
FOR WOMEN:
| Age | Athelete | Average | Overweight | Obese |
| 20-40 yrs | 12 - 20% | 21 - 33% | 33 - 39% | Over 39% |
| 41-60 yrs | 14 - 22% | 23 - 35% | 35 - 40% | Over 40% |
| 61-79 yrs | 15 - 23% | 24 - 36% | 36 - 42% | Over 42% |
FOR MEN:
| Age | Athelete | Average | Overweight | Obese |
| 20-40 yrs | 4 - 7% | 8 - 19% | 19 - 25% | Over 25% |
| 41-60 yrs | 7 - 10% | 11 - 22% | 22 - 27% | Over 27% |
| 61-79 yrs | 9 - 12% | 13 - 25% | 25 - 30% | Over 30% |
I go into more detail about methods of measuring body fat in Methods of Assessing Fitness.
Related posts:
- Obese Nation: Is Your Weight Causing You to Miss Out?
- Is Obesity Linked to Disease?
- Losing Weight vs. Losing Fat
- How to Choose a Personal Trainer
- Benefits of Exercise?
Topics: Uncategorized |
March 21st, 2008 at 3:25 pm
Nice chart. I wondered where I would fall in as far as my bodyfat % was concerned; nice to see it’d be average for my age. I always thought I was more on the overweight side, honestly!
Now to work on getting towards that athletic number…
March 24th, 2008 at 1:41 pm
I remember hearing about the skinnyfat situation years ago from a trainer. He said it was more common for women because women focus more on cardio and calorie restriction for weight loss and maintenance. But, I totally agree that skinny does not equal healthy.