It is important to note that the Body Mass Index is to be used as a general tool for determining a healthy body weight. Basically the BMI assumes a “normal” body weight for men and women of average height and average fitness or activity level. Several issues arise with this method and those are listed below:

• The “normal” proportion is used for all heights and weights even though not everyone has the same body type
• Even though taller people tend to be thinner on average, their larger bone mass usually skews their BMI to slightly larger values
• Having high muscle mass can result in a higher BMI because muscle is more dense than fat and thus for the same height someone with a lot of muscle can weigh as much as someone with high body fat
• In reality, the “normal” body weights for people vary from age, gender, and population

Thus it is important to take all this into account when trying to understand your BMI reading and also speak with a doctor or nutritionist before undergoing any new fitness routine or diet. One last thing to remember is that the “overweight”, “underweight” readings shown in this BMI Calculator are relative to a pre-defined average “normal” body weight. This means that for bodybuilders and very fit people, sometimes it’s better being “overweight” because to them the BMI is stating they are heavier than “normal” people, which is in fact the goal most bodybuilders want to obtain.