BMI, or body mass index, is how much you weigh compared to how tall you are. It is often used to check the health problems that come with being too fat or too thin. But BMI does not tell the difference between muscle and fat, which can make it wrong for bodybuilders who have a lot of muscle¹.
Bodybuilders usually have a higher BMI than the normal person, because muscle is heavier than fat. This means that they may be in the too fat or very fat groups, even if they have a low amount of fat. For example, a bodybuilder who is 6 feet tall and weighs 200 pounds would have a BMI of 27.1, which is too fat. But if his amount of fat is 10%, he would have a lean body mass of 180 pounds, which is good for his height².
So, bodybuilders should not use BMI only to check their weight status. They should also use other ways, such as body fat clips, electric current analysis, or water weighing, to measure their amount of fat and lean body mass. These ways can give a more correct view of their body shape and health problems³.
Or, bodybuilders can use a changed version of BMI, called FFMI, or fat-free mass index. This is found by dividing the lean body mass by the height squared, and then adding a change factor of 6.1 for men and -6.5 for women. FFMI can tell the higher muscle mass of bodybuilders and give a more real guess of their weight status. A normal FFMI range for men is 18 to 25, and for women is 15 to 21.In short, BMI is not a good sign of weight status for bodybuilders, as it does not tell between muscle and fat. Bodybuilders should use other ways to measure their amount of fat and lean body mass, or use a changed version of BMI, called FFMI, to tell their higher muscle mass. These ways can help bodybuilders reach their best body weight and shape, and avoid the health problems that come with being too fat or too thin.
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