Pros and Cons of BMI

 

Body Mass Index (BMI) is a popular measure of a healthy body weight. It is simple to calculate using any online BMI Calculator and is a useful tool for monitoring your body weight. It isn't perfect, however, and you should understand its strengths and weaknesses.

BMI delineates where normal weight crosses the line to overweight or obesity. An ideal BMI is between 18.5 and 25 (mine is 24). Over 25 is considered to be  overweight and a BMI over 30 is classified as obese. People with a high BMI have been shown to be greater risk of a list of health issues, including metabolic syndrome and diabetes, arthritis, fatty liver disease, high cholesterol and some cancers. But as a single indicator its accuracy and validity can vary a lot.

At BMIs over 30 the risk measure is reasonably accurate but it becomes less reliable below that. That is because BMI only considers height and weight and it can not distinguish between fat and lean muscle weight. So for example, a weightlifter with an unusually high lean muscle mass might show a high BMI.

BMI does not consider the location of fat deposits either. Belly fat tends to be more closely associated with health risks than fat in other parts of the body.

Even ethnicity can affect the interpretation of BMI. Asians tend to have higher health risks at significantly lower BMIs and Caucasians have higher levels of body fat at a given BMI than African Americans.

So is BMI a useful indicator? Yes. Its is easy to calculate and gives you a quick assessment of your weight. Just don't rely on it to the exclusion of other measures and factors.