For weight loss, stalling after the first couple of weeks is not uncommon. If you keep up with it, that stall usually breaks on it's own after a couple of weeks. The first couple of weeks on LC, you do tend to lose a lot of excess fluid (giving great scale losses), but that starts to stabilize over the next few weeks, then you start losing again. If not, it's worth re-evaluating your food.



As far as regaining weight, I'm sure there are a myriad of reasons, some of which could include carb creep, too many LC treats (homemade or specialty products), or indulging in full carb holiday treats/drinks and never making a real effort to get those pounds off again.



Lifestyle changes could be a factor - if you lost the weight on home cooked foods, but have since started eating out more for some reason (working more hours, traveling for work, etc), you might have trouble staying as LC as when you lost the weight, due to hidden carbs in restaurant food.

I've also seen some people who haven't made any noticeable changes in their diet, but as the body becomes accustomed to a certain carb/calorie level, it starts to conserve energy, resulting in a slow weight regain. You also have to consider how "broken" a person's metabolism was when they started LC - if their metabolism had a very low carb tolerance when they started, the body may respond very well at first, but because of the level of impairment before starting, slowly get worse over time, resulting in needing an even more strict version of LC to maintain as the years go by.

And then of course there is age - for some people, it's difficult enough to get the weight off to begin with, even on strict LC, but as the body slows down due to aging, it becomes difficult to keep it off. I'm talking about those who are at least 40 - but by the time you're in your 60's or 70's, it really slows down unless you're extremely vigilant with your diet, or exercise excessively, and by that age, sometimes physical ability limits exercise... and you can only limit your diet so much without sacrificing muscle. So sometimes you need to just accept a slightly higher than ideal weight.

Sometimes people set up an idealistic, but unrealistic goal weight, diet strictly to lose down to goal, but find it simply isn't something that can be maintained. Also, if you've been very obese, your muscle mass and bone mass needs to be higher than normal for your height, just to be able to support the excess weight you carry. As you lose fat, you can expect to lose some of the muscle mass, but you don't want to lose much of it, and you certainly don't want to lose bone mass just to get to some unrealistic goal weight.



I'm sure there are other perfectly legit reasons that people regain weight and never take it off again - surely others will chime in on this.