kinda same post but more to the point!!!

Because of your MMR. If you have low MMR you play with lower ranks, meaning you should win, so you gain less for a win, because well theyre lower, and you SHOULD win. If youre playing against worse people, it also means you lose more LP, because youre losing against people you shoukdnt be losing against. Ive had this, where i lose a lot more then i gain, then i fix my mmr, and right now I have fairly good MMR, so i lose ~16 and gain ~25. Hope this explained it.

Tl;dr: you lose more then you win, so your MMR goes down, and when its low you lose more then gain

could it be that your mmr is lower than the average of your current tier? let us check! http://na.op.gg/summoner/userName=newage2005+ yes, yes it is! who would have guessed!