What is BMI missing?
Is it possible to have a BMI in the "normal" range, and yet still be unhealthy? The answer is yes. Let's look at our two women from before, assuming they're both 30 years old and 5'6" tall.
Woman A: 150 pounds, 34% body fat. BMI = 24.2
Woman B: 160 pounds, 31% body fat. BMI = 25.8
According to their BMI results, Woman A is "Normal", and Woman B is "Overweight". However, if you look at a table for healthy body fat percentages, we find that Woman A is in the "High" range, whereas Woman B falls within the "Normal" range.
Body Fat Is Important!
Fat has gotten a bad reputation in our society. We are told to avoid fat, not get fat, avoid fat like the plague. But body fat is vital for healthy everyday functioning. It protects internal organs, is essential for proper nerve function, stores energy, and is needed for digestion and producing hormones. While too much body fat can definitely be unhealthy, too little body fat is also unhealthy.
What Should I Aim For?Healthy body fat percentages are different for men and women, and also change depending on your age.
|20-40||Under 21%||21-33%||33-39%||Over 39%|
|41-60||Under 23%||23-35%||35-40%||Over 40%|
|61-79||Under 24%||24-36%||36-42%||Over 2%|
|20-40||Under 8%||8-19%||19-25%||Over 25%|
|41-60||Under 11%||11-22%||22-27%||Over 27%|
|61-79||Under 13%||13-25%||25-30%||Over 30%|
Source: Gallagher et al. Am J Clin Nut 2000; 72:694-701