Amazed by how chronically underweight people come in two categories:
"The doctor said I really need to gain weight so I went to the gym to work out really hard and almost fainted and died it's so hard I don't get how people do it ;___; I consume the same amount of calories per day as a newborn baby and have no intention to change that because I start feeling weird (describes the classic symptoms of refeeding syndrome) if I eat more than normal."
"I inhale as much food as 15 men five times my weight who do 16-hour days hauling oil rigs through solid land by dragging them on ropes and in a prehistoric era the clan would have stoned me to death out of fear that I'm possessed by some famine demon. If you tell me to eat more I will fucking eat you too."
And the secret third thing: People who will swear on their life that they're #2 but it's painfully obvious to everyone except for themselves that they are category #1.
Also (because of fatphobia!) There is so little cultural knowledge of what refeeding syndrome looks like or feels like, or how to treat it, so just "I feel weird, exhausted, like my heart is pounding, every time I eat anything more than a bag of crisps" is about where most people leave it.
For complicated reasons, you can become really low on minerals and thus damage your heart when you're trying to start eating normally, so you need to supplement. The NHS recommends the following: Thiamine 50mg, 4x per day. Vitamin B CoStrong, 1-2 tablets 3x per day, and a "standard" multivitamin for your age bracket. Get your electrolyte levels checked by a doctor before you start, if you can.
They also recommend a lot of dairy, because it contains phosphate and other minerals you'll need on the way up - If you're lactose intolerant, get a lactase tablet for it, or lactofree milk.
Also, genuinely, doing things to stimulate your appetite (ie, short, heavy gym workouts that don't actually burn many calories but make you feel tired, smoke weed, cook things that smell good to make yourself hungry) can help.
