I don't think you need to feed that animal a liquid diet. I will explain in a bit, but I do have a question for you. You say you got your snake up to 300 grams, when this weight was taken, did he have any meals in him? If, so, then differnce between his empty weight then, and his 212 gram empty weight now might not have been so great. Now, I would assume that a liquid diet would not be put in a bowl and the snake allowed to drink it at will. In other words, you will be forcing the liquid into the animals stomach some kind of way. This is a very stressful event for an animal, especially one that you know has eaten in the past. If your animal has taken meals before, he will do it again, assuming something in his habitat hasn't changed, or is not correct (i.e. other husbandry issue). My opinion would be to try every feeding method you can, before you attempt this, try live, pre-killed and frozen thawed mice and rats before you force feed a liquid diet. I have a female that I got about 2 years ago. She weighed about 900 grams when we got her. She was treated for internal parasites and decided that she didn't want to eat for 55 weeks. Needless to say she lost about 250 grams. After being persistent and never giving up on her, she now weighs 1700 grams and eats mice like a champ (she won't touch a rat). One more story. I have a friend that has an Albino male that is about 6 years old that for the last 3 years will only eat four small rats a year. About every three months he will eat, and he shows no signs of sickness or weight loss. I also would like to add that he breeds like a champ. With all of that said, I don't think that after 3 months of fasting that you should consider your snake to be out of the ordinary and need to resort to such drastic measures. Hope that helps,