Drinking 8 glasse of water a day...is it mega important?

Is it mega important for weight loss? No.

From personal experience, yes it has helped. I did not drink nearly enough water a year ago either but now I do. Once you get over that initial hump of starting to drink it, it gets easier. Someone told me then, and it's actually true, that if you have a straw cup of water with you all the time, you will mindlessly drink it (just like a bag of chips if they're in front of you). I thought they were crazy but they were absolutely correct.