I'm seriously considering drinking, not a gallon, but a liter of whole milk a day. I have now reached 158 lbs and it's getting hard to gain. I'm aiming for 4500+ cals. My mom has got money, but she's not rich. And a liter of milk will give me 600-700 calories and protein for €1.10. Is this extreme? I'm a little out of options. There are no other relatively primal options this cheap, right?