For years, body mass index (BMI) has been used as a standard measurement that healthcare professionals use to decide whether their patient is at a healthy body weight. Doctors and trainers throw around the numbers, but can dropping a few figures into a calculator really tell you what's happening with your health?
The concept of BMI was first introduced in the early 19th century by Belgian mathematician Lambert Adolphe Jacques Quetelet to provide a quick and easy way to measure the degree of obesity of the general population along with a way to assist the government in allocating resources. BMI compares an individual’s height to their body weight. To determine your BMI, divide your weight in kilograms by the square of your height in meters. If you do not want to do the metric conversion, there are many BMI calculators readily available online. Once this value is obtained, you simply view a BMI chart to determine whether you’re within your ideal body weight.
Here are the basics of breaking it down:
- Underweight Less than 18.5
- Recommended/Ideal 18.6 to 24.9
- Overweight 25.0 to 29.9
- Obese 30 or greater
But how much emphasis should you really place on this number? As it turns out, a growing number of healthcare professionals and experts strongly believe that BMI is not a good representation of ideal body weight or health status.
BMI Isn't Everything
1. BMI does not take gender into consideration.
What if a female and male are the same height and weight? Will they have the same calculated BMI? Unfortunately, yes. The body composition for a female and a male are completely different and a female has a higher body fat percentage compared to a male, which can skew the results.
2. BMI does not take age into consideration.
Consider an older adult. He or she may be experiencing severe muscle tissue loss that occurs from aging or immobility, but he or she will often still fall into the recommendation or ideal BMI range because of their total body weight and height.
3. BMI does not take into consideration ethnicity.
Do individuals from different ethnic backgrounds all have the same body structures? No. According to various studies, some ethnicities naturally have smaller body structures and others are predisposed to disproportionate distribution of fat stores, both of which can skew BMI results.
4. BMI does not take into consideration athletes or those who are physically active.
For the average athlete or someone who is very physically active, strength training and building muscle mass are major components of this type of lifestyle. These individual bodies tend to be strong, in shape or considered to be "fit." However, when a BMI is calculated these individuals tend to fall into the overweight or even obese categories due to their percentage of muscle mass. In reality, any time there is a weight gain, BMI goes up due to the failure to recognize a difference between body fat and muscle noted in this measurement. With this in mind, this measurement should not be used for athletes or those who are very active.
So What Should I Believe?
Calculating your BMI is a very quick and easy way to evaluate potential health status and some research studies show correlations between BMI and future health outcomes.
However, do not let your BMI measurement dictate your overall weight status. It is important to remember that BMI is a simple measure, it does not take into account age, gender, ethnicity, muscle versus body fat or bone mass, and it treats all weights equally. In addition, BMI does not look at body fat distribution.
While healthcare professionals are still actively researching to determine the best measure of weight status, determining one’s weight and health status is way more complex. It is important to also look at other measurements and parameters such as body weight percentages, waist circumference, blood pressure, blood glucose levels, and cholesterol and triglyceride levels to determine overall status.
Remember, weight loss and body composition is not one-size-fits-all. Factor in parameters such as energy level, sleep health, overall health and your life outlook in addition to weight before you let a single calculation throw you for a loop.