How much weight will a grapefruit diet help me lose?

how much weight will I lose if all I eat is grapefruits and nothing else for 2-3 weeks, and don't comment if ya gunna say its unhealthy because I no guyz, but I don't care.
thanx. x x x

You won't lose much. In the first week you will lose water weight (~ 5 lbs), but after that your body will adjust itself to conserve energy and you will lose... nothing. So you'll starve, and you'll lose nothing. I don't know why this idea appeals to so many dieters when they could just eat normally and exercise.

Once you start eating normally you will gain the water weight back. You will also gain a few pounds due to your slower metabolism. Chances are you will weigh even more after the diet than before the diet. You will maintain your reduced weight only if you continue eating only grapefruits for the rest of your life... which I imagine won't be easy, if possible at all.

I will give you a word of warning- if you are on a 28 day contraceptive pill (ie: The pill), either use another form of contraceptive (like condoms) or don't go on the diet. There's something in grapefruit that makes the pill ineffective.