Okay for one thing unless your in some sort of contest dont even hope for 6 or 7% bodyfat because you will not get it. And at that low its almost impossible to stay at that level for any length of time. A low range would be like 15% and 12% you start to lose breast size very rapidly. I have no clue how tall you are but if your in the 5'5" range a good weight would be something like 115 or 120, and thats with a clean diet and an excercise program that has you working probably in the 5-6 days per week range. And remember to do weight lifting, not just cardio, drink lots of water and good luck to you. Oh and the bodyfat thing, women cant get to the low levels like males. A lower percent for men would be like 8-9% and for women around 15%.