This is the exact thing I'm planning on doing. I'm going to lose weight with a water fast. Restart my digestive system and then do weight lifting. Increasing your lean mass will increase the chances of you keeping the weight off and it's healthier. It's possible to be skinny and obese at the same time. Which is why weightlifting is important.
Have you done weight lifting before? If you haven't then you will achieve good results the first month. It's callde Newbie gains. Beginners to weightlifting will get good results AND lose fat at the same time.
Taking extra proteins will help but remember. Don't believe the hype about 1 gram of protein pound that is wasteful and they will be converted to glucose. I gram per kilo is good enough. Also always have eat a bit of carb after a work out. That way your body won't release hormones to catabolise the muscles.