Once you've been fat, it's very easy to be fat again. It's a bit like being an active alcoholic. One drink and you can be right back in all the misery from before. Of course, it takes more than one drink to get fully active again and it takes more than one doughnut or one half-gallon of ice cream to get fat again. But it doesn't take as long as you'd think.
For although we may look thin and actually are thin again, our body composition isn't quite the same and those well-plumped fat cells are just waiting to be plumped up again. It's common knowledge that people who lose a lot of weight often regain it all plus some. What is less commonly known is that while the initial weight gain may take years or even decades, the regain can take only a few months. Yes, it is possible to regain 90 pounds in a few months.
My own experience, while not so extreme, has proven this to be true. So I am conscious of this as I find myself wanting to eat more than what's on the plan. I still have a lot of weight to lose and I don't want to have to keep losing it.