13lbs in 3days liquid diet!

So I've been put on a  2 week liquid diet (not pre/op)  to lose weight in order to have surgery, I went to the cardiologist today I got on the scale and I'm down 13lbs in 3days I was like what!!! That's crazy! I don't want to keep calling my Nut asking questions but is that even healthy to lose that much weight so quickly? I'm getting 3 of the 4 protein shakes I'm suppose to have, having sf jello/pudding,cream of wheat and the progresso Lite soup. I don't like anything else on the list of things I can eat! I'm doing about 500-700 calories and 60g of protein a day. I started the diet Friday 10/17, and went to the cardiologist today 10/20 the diet has not been hard for me I haven't been hungry or tempted I've had a headache and was grumpy on day 1 otherwise it's been pretty easy, happy to be losing weight so quickly just concerned if it's healthy??

This is a quick weight loss to get ready for surgery.  If you do not have surgery, then the weight will come right back, almost as quickly as it came off.  As long as your body still has excess fat, it will burn that for energy. 

I have to lose 40lbs to have surgery, So I'll be alternating from the full liquid diet, to a low calorie diet after the two weeks are up until I lose the 40lbs but the way I'm losing, I'll prolly have the 40 off in less than a month! So no ma'am!! This weight will not be returning or I will not be having surgery and my dear THAT IS NOT A OPTION! 

Oh and thanks! I didn't know that, now I feel a lot better because my body has plenty extra fat to use as energy lol thanks again!!

When we cut back suddenly and dramatically on food intake, the body draws on the most accessible fat store which is the water soluble glycogen. This is the store we maintain for fight, flight, famine. Once the situation ceases to be an "emergency", th body needs to replace that glycogen store. But each pound of glycogen requires four times its weight in water. So your body, over the next few days will start to rebuild glycogen stores. 

So early rapid weight loss is fat and water. And now your body will be losing fat but gaining glycogen,  so loss will be much slower. Some people even gain.