Tag Archives: body composition

Don’t get hung up on your BMI (Body Mass Index)

The usually reliable WebMD has a very nice quiz on fat that I recommend you take. It’s fun and can fill you in on some aspects of body fat that most folks don’t understand.

Having said that, I would like to take exception to the final question in the quiz which asks which BMI category is healthier? Anything below obese; The low end of normal; Anything in the normal range.

I wish we would do away with the BMI as a tool in evaluating fitness, health, fatness, you name it.

First of all, a lot of people think it tells them their percentage of body fat. It doesn’t. A person’s BMI is calculated as her weight in kilograms divided by her height in meters, squared.

It is an index, not a body fat measurement.

The readings are as follows: Underweight: less than 18.5; normal weight 18.5 – 24.9; overweight 25 – 29.9; obese BMI of 30 or more.

Second, it doesn’t take into account where the fat is distributed on the body. Fat around the belly is much more dangerous than fat elsewhere.

Arnold Schwarzenegger as Conan the Barbarian. Six foot two inches tall, 257 pounds, BMI 33 - obese?

Arnold Schwarzenegger as Conan the Barbarian. Six foot two inches tall, 257 pounds, BMI 33. Not what most of us would call obese.

“The usefulness of BMI is not great when considered on an individual-to-individual basis. In practice, BMI is most appropriate for large sample populations or in a clinical situation to quantify risk for a patient who is clearly overweight and overfat at the same time,” according to Professor Michael J. Ormsbee, creator of the Course Changing Body Composition Through Diet and Exercise which I am taking.

Dr. David Edelson, MD, writing for the Obesity Action Coalition  says, “…there is no accounting for differences in body frames, or even more importantly, body composition.

“BMI, while being a reasonable estimator of obesity in someone of average conditioning, becomes a terrible predictor in people with either lots of lean muscle (trained athletes) or very little lean muscle (severely de-conditioned individuals). BMI does not tell you anything about what is going on inside someone’s body, which is what we ALL should really be interested in.”

Keith Devlin, on National Public Radio, gave “10 reasons why BMI is bogus

His first reason is “The person who dreamed up the BMI said explicitly that it could not and should not be used to indicate the level of fatness in an individual. The BMI was introduced in the early 19th century by a Belgian named Lambert Adolphe Jacques Quetelet. He was a mathematician, not a physician. He produced the formula to give a quick and easy way to measure the degree of obesity of the general population to assist the government in allocating resources. In other words, it is a 200-year-old hack.”

You can read the remaining nine reasons at the link.

I have written about belly fat several times – How bad is extra belly fat?, What about belly fat – central obesity?

In addition there is: What is a good way to measure body fat?

I think you are a lot better off with this tool than the BMI.

Tony

7 Comments

Filed under belly fat, fat, Weight

What Are Some Differences Between Fat and Muscle Tissue?

So many people are hung up on their body weight, but fail to realize that the more important issue is their body composition.

All there is to us is fat, muscle and bone. Our body weight is equal to the sum of these parts.

I hope this illustration will help you to see the issues clearer.

It is clear from this picture that fat weighs less than muscle, so it takes up much more room than muscle.

It is clear from this picture that fat weighs less than muscle, so it takes up much more space than muscle.

Once you have an idea how much more space in your body that fat takes up, you can understand the importance of knowing your percentage of body fat. You can read about how to measure your body fat percentage in an earlier post.

Once you know this you will have a baseline from which to work. This is important because often when a person starts to do cardio and resistance exercises his weight doesn’t tell him there is much change going on. Yet, if he is burning fat and building muscle, his body will be changing in important ways. Shirts will fit differently, pants will become looser around the waist line.

Another important consideration in body composition is that one pound of fat burns about 5 calories each day while one pound of muscle burns 50 calories in a day. So, once you get yourself on the road to fitness and start building muscle and burning fat, you will be transforming yourself into a calorie and fat burning machine. You will have started a wonderful positive spiral.

It is important to understand your body fat composition because while you may presently think you are at a good weight, if you have too large a percentage of fat, you may not be all t hat healthy and may be headed for medical problems despite you ‘good weight.’

Similarly, if you are overweight, once you learn your percentage of body fat you will have a guideline against which to measure yourself by and you won’t be troubled by the fact that you ‘aren’t losing weight,’ when you begin an exercise program and start trying to eat in a more healthy manner. You will be burning off fat and muscle weighs more than fat. Often when an overweight person starts working out and getting healthy he/she finds that their close fit looser/better despite no change in their weight.

Tony

Leave a comment

Filed under belly fat, body fat, calories, cardio exercise, Exercise, healthy eating, healthy living, nutrition, obesity, overweight, percent of body fat, Weight