PolyPinoyPuppy:
I hope you don't mind me asking, but why did you lose the weight in the first place? A hundred pounds in a year is about 2 pounds a week for 52 weeks, which is at the upper end of a healthy rate of loss from what I understand.
I second this. If you want to gain and gain sustainably, you need to resolve why you lost the weight in the first place. The way you lost weight is somewhat concerning. If you gain more weight, you will likely have a major setback - or at least yo-yo for a while.
Being fat is more than a body shape. It's a way of life. And if you aren't mentally prepared for that lifestyle, you will be miserable.
