2 weeks is very plausible. I did it last March. Not to lose weight but begin the healing process. All I had during that 2 weeks was water. Your body will start to look for energy, after the first 8-12 hours it will look for it in your digestive track. It’s mostly waste by that point. Your body will then look to your muscle tissue for energy, not ideal. Once you pass the 3-5 day threshold, your body will then kick into starvation mode, taking your fat and converting into energy. Stored in your fat are essential nutrients. So now your getting water and nutrients that your body needs to survive. You’re also shutting down your digestive track and allowing your body to utilize that energy to detox and cleanse itself. It’s hard for the body to detox if you keep putting toxins in all day. The body is composed of trillions of cells that emit all types of waste, cellular waste, digestive waste and so on. Detoxing will help get rid of those things and cleanse your arteries, colon and everything else.