Your username worries me as to how far you will go. No disrespect, but we've all heard of this anorexic-chic model look - I thought, thankfully, it was on the way out. Don't go too far & ruin your health as well as your looks jadey.
As others have said starve yourself or indulge in a liquid diet along with non stop cardio exercise. This is, however, really stupid, you will just end up looking gaunt and saggy and have no muscle tone. Also when you start eating properly again, you will pile on the weight and most likely end up heavier than you started.
Oh forgot to mention, as you're possibly a Model Jadey, you could try eating tissues, drinking loads of water and snorting Cocaine, that apparently works, but I'm in no way advising or condoning you actually do this. It's just a well known practice in the Modelling world.
Imagine your body as a car. It needs fuel, water and oil to run smoothly. Take away any of these 3 vital components and the car will not go......................eventually it will deteriorate and be sold for scrap.
Your body needs fuel (food) and water for it to function properly along with nutrients and vitamins and minerals.
Do not deprive your body of any of these.
Just another note too........................take it from a man that knows, ....men do not like shagging someone who resembles a broom handle.