user i believe you have an eating disorder and are in denial. If you do have an eating disorder it is okay. Just being aware and mindful is half the battle.
No guy who is 6'1 accidentally ends up 138lbs, let alone 150 or even 160 without conscious effort. You'd have to be eating under 2000 calories every day for months and months to stay this low. Your maintenance at 6'1 is probably 2250 or so.
This is not meant to bash you or anything, its just important to come to the realization that your brain is working against you.
For whatever reason most of the choices you make are on the side of staying skinny. You probably don't even realise it.
The most important thing to know is "calories in vs calories out." All the fad diets and popular trends bow to this one golden rule.
If you are losing weight it means you aren't eating enough calories. If you are not gaining or losing it means you are burning as much as you eat. If you are eating more calories than you burn it means you are gaining weight.
It's basic physics, metabolism can be considered a black box. You only need to know the initial and final products in the reaction (calories in, calories out).
So knowing that calories is all that matters, you just have to make the concious effort to count the calories you consume, and make sure to try and get 2500-3000.
Preferably 3000-4000 since you are EXTREMELY underweight.
But please make sure to actually count your calories for your meals at least the first couple times because almost everyone severely underestimates or overestimates how much they eat.
In your case i am very confident that it will be difficult for you at first to stick to 3000+ actual counted/measured calories because your brain and body will tell you this is too much.
You'll be eating around 6-8 plates of food that are about the size of two fists a day. Please try to avoid liquid calories though as much as possible (eg non-diet coke or weight gaining shakes).
Attached: 1560870331943.jpg (584x657, 231K)