Gained 10 lbs in 10 days in my first week of lifting. Words of caution to fellow beginners.

I was 160 lbs the day before Thanksgiving (Nov 22) and I weighed in yesterday at 170 lbs. Needless to say, I was shocked to see I had gained so much in such a short time.

I have lurked on this subreddit for a while with my normal account, and the one takeaway I got was that I needed to EAT MORE. Everything from the sidebar comment about fast metabolisms to guys' comments about eating while they're typing made me realize that probably the reason why I had failed twice to gain mass in the past was due to my insufficient caloric intake.

Well, problem solved, apparently. However, I didn't gain just the 1-2 lbs a week that I had anticipated but an entire 10 lbs, which means I probably put on a lot of fat. In case it doesn't come across, I'm not happy with this. But I do know that the reason for this is that I didn't count my calories. I did make sure to get 300g of protein a day for my estimated 3000 calorie diet, but for the most part, I just made sure to always intake a good amount of protein, fat and carbs each day.

So for anyone who feels they can't gain weight, YOU CAN! You just have to make eating a chore the way I did. But BE CAREFUL because you don't want to overeat like I did. I never counted calories when I was losing fat, but I realize now that I personally need to for mass gaining. The whole approach of eating everything in sight does not work for me, and I don't want to be a strong fat-ass. I was really lean before this and I don't want to lose that entirely as I gain weight.

I just hope this experience helps someone who might be in a similar boat as I am in.

EDIT: For 12 weeks before Nov 22, I had been on a low calorie, paleo-based diet in combination with cardio-based exercise. I lost 15 lbs in those 3 months (went from an unhealthy 175 lb to a lean 160 lb). Maybe this had an effect on how my body reacted to this influx of food? Also, no supplements have been used other than Whey protein.