You don't just chose to have one. It is a mental illness. That's like someone asking how to develop depression.
And even if you could, I'm telling you right now you don't want that. It won't kill you quickly like you seem to think. Many with eating disorders live years to decades before it takes them. And as long as you are alive you will be in hell on earth. Think things are bad right now? They'll be 10X worse once an eating disorder is on board. All of your thoughts will be consumed by food and weight. From the moment you wake up to the moment you fall asleep you are thinking about food and number and calories and clothing sizes and how you look in the reflection of the window and how easily your fingers fit around your other wrist.
An average day in my life:
-Wake up at 1am shitting my brains out from the laxatives I took last night. Have my legs go numb while sitting on the toilet from poor circulation.
-Wake up at 4am shitting my brains out from the laxatives I took last night. Apply some aquaphor to my ass because I have a rash like a fucking baby from the constant diarrhea.
-Wake up at 7 and weigh myself after shitting some more. Hate the number on the scale, even if it's my new lowest weight.
-Take body check photos and compare them to old ones for hours.
-Think about how I'm not going to eat anything until noon.
-Noon comes and I tell myself I'll only eat a little bit.
-Eat more than a little bit because my body is starving and I've lost self control. I still ensure it's not very many calories.
-Measure my whole body. Hate all of it.
-Take laxatives to compensate for how much I hate myself even though I know it won't actually cause any weight loss, I'm just addicted at this point.
-Make plans for how little I'm going to eat tomorrow. I may or may not follow through.
-Browse DoorDash for four hours planning meals I won't allow myself to eat. Possibly buy one and binge.
-Go to bed knowing I won't get a good nights rest because I took so many laxatives I'll be up all night shitting.
My hair is falling out. My skin is always dry. My lips are always chapped. I have poor circulation. My ass is raw from the laxative abuse. My bowels don't work properly without laxatives anymore. My electrolytes are all fucked, which hasn't killed me but it makes me feel constantly sick. I'm anemic. I'm always fatigued. I either don't eat anything or I binge, I have no in between and I have lost control over which one it will be at any given moment. And I haven't even come close to my goal weight despite having relapsed over a year and a half ago.
You do not want this. You will not die quickly. And you will be living a life consumed by numbers and food. You will hate life a million times more than you think you do now.