Anorexia is an eating disorder that is when a person is so obsessed with their weight that they don't eat enough for their body to stay healthy. I hope you're not falling into this. I noticed that you are obsessed with tanning to the point where your body is reacting badly. Don't be overly concerned with your appearance or you will be miserable your whole life. Plus nobody like people that are too into their appearance it is superficial, and shallow.
With all fasting, you'll lose weight, but how much of the weight you keep off depends on what you do once you've broken your fast. If you eat a low cal/low carb diet, the weight should stay off. If you go for pies and cakes, it'll all go back on and more.
The best reasons for fasting are to cleanse the body, rather than to lose weight. I generally do a two-week juice fast every three months to get all the accumulated gunk out of my system. While fasting, you can expect an increase in bowel movements, and if you're a woman, you may get some menstrual disturbance.
Fasting differs from anorexia because you are regularly taking in nourishment and it is for a limited period only.
Fasting is not only safe, but it has health benefits.
-it detoxifies the body
-gives you more mental clarity
-extends life expectancy
-improves the body's healing power (energy diverted from digestion to metabolism/immune system
Have a look into intermittent fasting, it has gained a lot of traction over the last few years, especially in the bodybuiding community.
Fast for 16 hours. During this time, you CAN have coffee, with some milk/sugar (provided its under 50 calories), then get all your calories in a 8 hour window.
It makes adhering to diets easier as well since you're able to get that feeling of being full with your meals so close together.