A 20 year old five foot tall female. that weighs 130 pounds want to lose 30 pounds. She is currently at 23 percent body fat and wants to drop to 20 percent body fat.?

If she is 130 pounds and 23% body fat (very respectable, and at the low end of the NIH and WHO "normal" range for a woman), then she has 130x.23, or a total of 29.9 pounds of fat in her body. She could lose every bit of that and still not meet her goal.

A more reasonable goal would be to drop just a few percentage points. A healthy goal for this person might be around 20% or so, so she could possibly lose 5 or 6 pounds.

The best thing this person could do would be to simply raise her level of fitness and eat a bit healthier and not worry about the scale.

Amputation of a limb is another option to lose those 30 pounds. A leg would do (but, having only one leg myself, I don't recommend it!)