I had always believed that if you wanted to lose weight you had to cut calories significantly but now I looked at the nutrition plan and it says I need to take in 1800 cals a day!!! (I had been aiming for 1200 cals) I've looked at a lot of old posts about diet and I think I understand the logic behind taking in so many calories but it still goes against all my previous beliefs.
So basically I'm frightened that I'm going to end up gaining a ton of weight.
How much do you weigh? Take your weight, multiply it by 10, then add 1/2 your bodyweight to that. That is an estimate of your base caloric requirement (just to exist) then add on daily activities and you will se why you need more calories. Going too low causes your metabolism to adjust to the perceived famine by slowing down so you require less calories. It also looks to get rid of hungry muscle and stores more of the food you do eat as fat, in case the famine continues.
You may experience an initial weight gain if you suddenly increase your caloric intake a lot. Try gradually adding in calories each week until you are at the goal amount.
Good luck!