So I did the flex plan for a couple late last and lost almost 20lbs for my wedding. But because of health issues (my thyroid decided to act stupid) I gained all of it back plus 20lbs . Ok, so now here is my question, what is the differences of the flex and momentum plans?

Ok so just kidding I did the core plan when I did it.

Core is now simply filling.
Flex is now Momentum but they encourage you to fill your points with filling foods.
I'm relatively new at this, sorry if i sound confusing.

With Momentum you get a certain number of daily points, then 35 flex points to use as you choose on a weekly basis. The flex points don't carry over, so if you don't use them you lose them. You also get activity points. I hope this helps. The filling foods are the healthier food options that will help you stay full longer and are also part of the Simply Filling plan option.

Actually, the Simply Filling Technique (old Core) seems to work better for those with thyroid issues.