Not really true. What you are saying. Yes, you lose some water weight. You also lose a lot of fat. And you don't lose a lot of lean tissue because keeping your protein levels higher help to preserve lean tissue with Atkins.
And no you don't "gain it all back" necessarily. Sure. Any time you don't modify your eating habits and keep them modified for a lifetime you are going to gain back what you have lost. This is true of every single diet out there. Not Atkins specific by any means. Atkins is NOT as restrictive as you might think. In fact in many ways it is the ideal diet because you modify what you eat, not necessarily how much. Yes you do tend to be less hungry without constant blood sugar fluctuations, but any calorie reduction is incidental, not required. With Atkins you can eat when you are hungry. You eat healthy food. Meats and Vegetables mostly. But you can also have fats and dairy and eggs and some fruit (mostly lower glycemic fruits). You do tend to avoid grains, and starchy foods as well has highly sugared foods.
I lost 50 pounds on it back in 2000 and kept it all off for about 3 years. I have gained back some of it, but I still have nearly 30 pounds of what I originally lost gone. I have friends who have lost as much as 100 pounds or more on it. Yes, if you go completely off and start eating like you used to you will start to gain. This (I repeat) is true of any diet you do. There is nothing magical about any diet that you may try. When you go off them and don't eat as you should you will gain BACK the weight.
I was only offering a suggestion to anyone who may wish to take the weight off a little faster. How you keep it off will really depend on how determined you are to keep it off.
Atkins works by depleting glycogen stores, and then tapping into your "reserve fuel" which is your fat stores to create energy. This means that you are burning your fat at a much more rapid rate. Read the book. If it doesn't make you want to try it then don't. But don't just listen to what people who don't know about it have to say, because then you are just repeating rumors, and you really don't know.
I've had people say right in front of me that "everyone I know who has ever been on Atkins has gained it all back and then some." What a lie! It really disturbed me because the person saying that was my own mother and she has two daughters who have lost considerable weight on Atkins and who have NOT gained "it all back" and certainly not "and then some" and yet her other daughter has been on weight watchers many many times, and yet has managed to always "gain it back and then some".
Ok I'm done. Take it or leave it. It works, it works quickly. Sure, there is some water loss, sure if you do it and then go off it you will gain back (almost immediately) some of that water weight. Carbs tend to cause your body to hang on to extra water. That is natural. But not all of what you lose is water. I know for myself there is no way I lost 50 pounds of water (only).
So just out of curiousity, do you guys know what professional body builders do when they are done gaining muscle and just before an event where they have to show off their muscles? They have two phases, one they call "building" and the other is their "cutting" phase. How do they "cut" the fat they put on during the muscle building phase without losing the muscle they worked so hard to get? They reduce carbohydrate consumption. Low carb. This preserves muscle because they still get plenty of protein, but it reduces their fat levels and retained water levels. This makes of a nice lean appearance with minimal muscle loss.

It makes me feel sure that it's gonna be permanent.
It plays in my head frequently, often when I'm running down the trail. Sometimes, I alter the soundtrack that plays while I'm morphing into a reasonably sized super model. Give it a try.
Cheers to you all!