Its just your body's way of fighting back. Before doing a fat-fast you should make sure you have tried a strict low-carb diet (induction), and then, if you are still stuck, try a fat-fast. Fat-Fasts are usually successful because the people who go on them got seriousally stalled. In my case, I get stuck eating 1000 calories and less then 10 carbs, and I am stuck. The only way out of the plateau (set-point) is intensive excercise for several days (try biking 8am-8pm for 2 days with friends), or do a fat-fast. Depending on your motovation, most people choose one of the two. The easy way and best way to do a fat-fast is macadamian nuts with cream cheese. Dip them in the cream cheese and maybe eat a couple calories in protein (maybe a extremely small piece of chicken, the size of your finger). If you fail at it, don't worry. Its your body fighting back, it wants to be heavy. There are also several major stallers (weight gainers) to look out for and a few other ideas I've found to be true:

1. Anything sweet (even aspartame or splenda). You must keep these occational. The sheer taste of something sweet does increase insulin levels, though not dramatically,... it may be significant for anyone who is stalled.

2. The biggest staller: Cheese. Cheese is VERY high on the GI index... why atkins allows it is beyond me. Its as bad as carbs. Got that? Cheese=Carbs

3. Watch your calories, eat enough that your not starving, but not really content. None of this: eat 100 times your body weight advise I see everywhere. That isn't scientific.

4. Try walking for an hour on the tredmill or outside for just an hour or so. It can really jump start ketosis. Its even better BEFORE your first meal, if you can do it mentally.

5. Watch your protein, 500 calories of pure protein is like 250 calories of carbohydrate. Carbs are twice as bad as protein, but protein is bad too. Choose fatty meats. Fat is the one thing that doesn't raise insulin badly.

6. Try eating INFREQUENT meals. People are being lied to. Man has never eatin 3 meals per day. Shoot for once a day (unless your diabedic). The drops in insulin through this forces weight right off you, and when it is raised, you maintain.

7. Keep drinking your water. Just chug a ton before going to sleep, and chug a ton in the morning. You will feel better all day.