Starting again and increasing calories.

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I have been on MFP since Jan and losing slowly but lost 13lb so far and have another 10lb to go, I have not been eating anywhere enough calories (not intentionally but through being too healthy and everything being low fat etc). I went away last week and have had a good few days of not logging my diary, I have gained 2lb which I know I will lose again,but I feel its a good time to start again and do it properly and to eat to my 1200 target every day. Will I still lose or will I gain first, and are there any foods that are good to increase calories intake, I have heard of peanut butter being used quite a lot, any advice would be appreciated.