I once measured my body fat at school gym. They measured three places in my body(arm, thigh, waist) and added the data together. I have more than 25% fat..
Then I began to do exercise, after three months, my body fat remained the same..
Some guys only have body fat less than 10%.

the average body fat percentage for human is 15%. Women may have more than men. Don't worry. Yours may be at the normal level. Michael Jordan's percentage is 3% which is quite unbelievable.

同意。女性不但平均body fat 多于男性，而且必须维持一定的比率才算健康。任何女性如果低于10%， 激素分泌就会不调，是病态，可能难以受孕。