just a quick note incase you read earlier posts about experimentation with eating habits. it is unsafe for females to have too low a body fat for extended durations. there have been studies done on female athletes such as marathoners who have extremely low body fat. one side effect is that you lose your period. some women see this as a benefit but it comes at the price of decreasing bone density. over time your bone density will get lower and lower until it reaches that of say a seventy year old and you'd start breaking your hips. those athletes had their bone densities scanned and found this out and some did actually break bones. so remember, for females to have extremely low body fat is a health risk.