I've been eating between 800 and 1000 calories a day for the last week and a half, and it's working pretty well so far (9 pounds in 10 days). I realize both that A) The rapid weight loss is because I'm so big and B) The calories are very low, again because I'm so big (2500-2700 would be maintenance for me).

I'm wondering if anyone else is or was on a low-calorie diet and how it is working/worked out for you.

How long will it be before your body adjusts and you only CAN eat 800 a day without gaining? How long before the plateau hits?

Any advice would be greatly appreciated!

While I'm sure you will find some people who have done a very low cal diet I would highly recommend you spend some time looking through the calorie counting board. Weight loss is a marathon not a race and it really is about finding a lifestyle change otherwise you'll never be able to maintain your loss. This is just my opinion, but it is completely unnecessary go that low on your calories to lose and it is unhealthy. It will also slow your metabolism WAY down and the only way to break through a plateau (completely impossible to say when you will hit on since we're all different) will be to increase your cals and/or exercise. Your body will also go into reserve mode pretty quickly and weight loss will slow down. You should take a look at freedieting.com they have a fantastic calorie calculator and info on calorie zig zagging which can prevent plateaus and lots of other great weight loss info. For reference, I'm eating an average of 1600 cals and still losing 1-4 lbs/wk. Good luck!

I wouldn't recommend a ultra-low calorie diet, from personal experience it ends up a lot more trouble than it's worth. At your current weight I highly doubt you'd plateau anytime soon (maybe after a year or so) but you would most likely be damaging your metabolism.

When I first started last year I didn't really know about calories and basically my lifestyle change involved cutting out all junk food, soda/juice, candy, sodium, fast-food, ... . I limited myself to 3 sensible meals a day with no snacks. I didn't weigh myself but I went from a tight size 24 to 22 in about a month (I'm guessing 25+ lbs). After about 6 weeks or so I started getting frequent dizzy spells and even blacked-out a few times. A trip to the doctor to confirm that I wasn't dying of a brain tumor, but I found out the problem was my 'diet.' Basically I was eating 800 calories (or less) everyday. I had no idea it was that low and after consulting with a nutritionist I upped my calories to 1600-1800. When I upped my calories I immediately gained 10 lbs (literally within 3 days) and my weight loss stalled at that higher weight for a few weeks while my body adjusted and my metabolism revived itself. After that I started losing again. I lost 100 lbs in about 8 months eating around 1600 calories/day (and that's with minimal exercise). Since December (when I started weighing myself regularly) my weight loss has averaged a little more than 2 lbs/week and I'm eating anywhere from 1200-1800/day depending on my activity level.

While an ultra-low calorie diet may seem like a great quick fix now, the extra few pounds you might lose are sooooo not worth the damage to your body. By upping your calories to at least 1200 (I'd suggest closer to 1800) you'll get the same results but without the damaging side effects. It doesn't seem like 400 calories could make that much of a difference, but it does. Save yourself pain later and aim for a slightly higher calorie diet.

I lose the exact same 2.2-2.5 lbs a week on 1300 calories a day or 1500 calories a day, and those 200 calories a day are a tremendous improvement to my lifestyle.

I've done many, many extremely low calorie crash diets in the past, and in my experience there are far more risks and downsides than benefits - physically, physiologically, and emotionally.

I also know that the euphoria of losing weight quickly, makes it difficult to listen to anyone advising you against it. I know I ignored all of the good advice I got, until I experienced some of the ill effects personally. Even then, it was hard to give up that kind of dieting because of the perceived rewards on the scale. Fast weight loss is tempting, and the risks seem remote (until you experience them, it's all stuff that happens to someone else, not you).

If I could do it all over again, I would avoid the vlcd's, I think they contributed far more to weight gain over the years than weight loss.

Ah, that's what I was afraid of! I'm sure you're all right about the damage not being worth it. I guess I was just feeling like the hard part should be willpower, you know? Like if I could make myself do it it'd be fine.

I will try to do 1200 or so.

I would consider my diet to be low calorie (1200-1500 cals usually). Anything below is apparently starving yourself - not sure how true that is but it's just something I've been told many times so it kind of stuck. Occasionally I dip below 1000 but not often.

In your case you have *does math* 130 pounds to lose. I'm just not sure if super-low-cal is going to be sustainable throughout your weight loss journey
If you can do it, great, but do you think it's something you can do for the next 2 years or however long it will take? If you think you can, then by all means stick to it, but keep your health in mind