Know all about Body Mass Index (BMI). (Part-2)

In the Part -1, we learned about what is Body Mass Index (BMI), how BMI calculation is done and history of BMI.
In this part we will learn about the significance of BMI as a body fat indicator and limitations of BMI.

Importance of Measuring BMI

BMI as a health indicator has been discussed a lot in the medical community. Though, it is measured in numbers, yet it is considered just as an indicator.
BMI is often used for risk assessment for general population. Numerous research studies have concluded that BMI helps to detect health issues at an early stage and can be very helpful to prevent fatal diseases.

A body mass index in the low range signals that you could be malnourished. Maybe your body isn’t properly absorbing nutrients or maybe you’re just not getting enough calories to support your activity level. 

As a rule of thumb, as a person's BMI increases or decreases after a certain limits, the person's risk of having some certain disease increases. Studies shows the link between BMI and several diseases. As BMI increases, so does the risk of:

• Diabetes
• Cardiovascular disease
• Stroke
• Hypertension
• Gallbladder disease
• Osteoarthritis
• Sleep Apnea
• some Cancers

BMI Accuracy and Limitations

Now that we know how important BMI can be a starting point to evaluate your health, it isn't flawless. 

The optimal weight that is predictive of health status and mortality is likely to be dependent on age, sex, genetics, cardiometabolic fitness, pre-existing diseases, and other factors. - “The Health Risk of Obesity”, Ahima and Lazar

The inaccuracies comes because the index doesn't consider many major factors. For example, 

• BMI does not consider gender, and women tend to have more body fat than man.
• It doesn't distinguish between body fat and muscle mass when it takes weight in calculation. Muscle weigh more than fat for the same volume. So according to BMI a body builder can be obese even if he is toned and fit.
• It doesn't consider the parts of the body where the fat can be for example it doesn't measure waist.
• Young children naturally start out with high fat and tend to get leaner by age and in their case a normal BMI can give incorrect indications.
• And also, BMI benchmarks can vary with different ethnic groups.