Lol...6 litres seems like a lot of milk every day bro. Likely a lot of fat as well. You'll likely end up with constant milkshake shits too. Never heard of this theory.
around 14 years ago when i was 16 -18 I drank a gallon and a half of milk a day
I read that arnold drank a gallon and a half also. it came out be almost 200grams of protien if i rember correct.
back then milk was around 1.69 a gallon.
i knew nothing of protien powders and all the fancy stuff
ofcoarse I was broke just out of highschool trying to gain and lift.
Lots of weight gain both muscle and some fat
thats back when i was 18 and could handle the calories and eat almost anything