I lived like this for two months and nothing happened, I only lost 15 kg. I remember that I was very worried then and because of work, session and travel was very busy and restless, I smoked a pack of strong cigarettes and a half and drank 3 cups of coffee a day. Oh yes, I had insomnia then, I did not sleep much. I looked silly, I stopped looking after myself, became very thin and my clothes became big. In general, I think that all this is individual and depends on what kind of safety margin you have and how strong your body is, in terms of how much you weigh, how much more than normal and how psychologically stable you are and how physically active you are every day. I think someone can withstand three months or half a year, but someone who weighs 40kg and breathes in incense and won't last a week. but I still remember that I did not really control this process, I just once got sick of eating and I stopped, and then the communities of various anorexic women and those suffering from bulimia were still popular. So, they shared their experience that in order to lose weight even more, they deliberately drove the body into stress and lived in stress, and if it did not work out, then they used stimulants. roughly speaking, their diet consisted of coffee, cigarettes and cocaine. and they lived like that for years.
It depends on why you chose this life for yourself. Most likely, it is either stress or a desire to lose weight. If you are on such a diet due to stress, then you will not die. Yes, if you have some kind of grief or shock, there can be so much adrenaline in your blood that you won't even be able to eat an apple for some time: you will immediately vomit. And in this state, you can lose 300 g of fat daily (by the way, this is how much a soldier loses in a war from stress). But the body is not a fool and will not let you die from stress. After a while, he will turn on the survival mechanism - and you will get out. Any stress cannot last forever. Even if it lasts a long time, the body after some time will cease to perceive it so sharply and will say: “Yes, I suck, life is shit, but let me eat it already, eh?”. And it will begin to slowly return the owner's appetite. Acute stress, when even an apple is sick, usually does not last more than four to six weeks. By the way, it is no coincidence, according to tradition, that 40 days are said goodbye to the deceased, that is, the first 40 days after the death of a loved one, we can no longer think about anything, we lose our appetite and see life exclusively in black. But after 40 days we say goodbye for good, the acute phase of stress passes, and we are slowly returning to normal nutrition, so you will lose 10-15 kilograms, but you will not be able to die. But if you are on such a diet, because you decided to lose weight in this way, you will die easily. And you will die quite painfully. After a couple of months on such a diet, your metabolism will critically slow down. Hands and feet will become wadded, because energy will cease to flow into the muscles. You will look like a stupid vegetable. Further it gets worse. Multiple organ failure will begin when the liver, stomach, and all other organs slowly fail. You cannot even absorb 400 calories. Further more unpleasant, anorexia is not only the inability to eat, but also irreversible degenerative changes in the brain, that is, you end up in a psychiatric hospital. And maybe you will get out of there, but since the degenerative process is irreversible, then even leaving the psychiatric hospital, you will return to your 400 calories, because with your weight of 30 kg it will seem to you that you are a fat pig. In no more than a year of such a life, you will die from this very multiple organ failure.