I'm in a "eat all the time" phase atm, more stuff in more stuff out pretty simple.
4kg's in a month is prob alot of fluid.
Eating more is hard at first, getting it all down stretching the stomach out a bit. The longer you keep up the eating, you'll start realising that its easier to get the same amount of food down.
Weight gain is how you see yourself going, if you think your putting on a bit to much fat, cut back on the food a lil bit.
Good luck in your goals.