Hi first of I'm a young guy and skinny normally I don't really weight train much just some benching but never really improved on it. Last week I started a new intense workout plan and yesterday I really worked and fatigued all my arm muscles. I spent about 2 hours on them and when I woke up this morning I noticed I weighed a couple pounds heavier than I normally do. I usually keep track of how many calories I eat everyday and I know yesterday I didn't eat anymore than I normally do so I was wondering if the muscle gain kicks in that fast? Or at least on a scale?