I disagree that fewer than 1200-1400 or whatever calories is insufficient, particularly for someone my size. I think our society is really hung up on "eating enough" and getting "value" for our money. Look at us all, and then look at our food habits. As a society, we eat WAY too much and many people have the crazy idea that if we go a few meals or a few days without food, we'll starve or something. That's garbage. We just don't need as much food as we've been taught to think we do (and I think our bodies provide proof of that). I've gone as much as 30 days on fewer than 400 calories a day (modified fasting for therapeutic purposes) and came out MUCH healthier on the other end of it. I wasn't taking a multivitamin either, just making sure my calories were high-quality calories.

And saying that 2000 calories is required for proper nutrition is silly too, if you consider that eating 4000 calories you could still not get appropriate nutrients by eating bad food. It isn't CALORIES that matter for nutrition, it's food quality. As long as you're eating food which has high nutritional value, you can get by on far fewer calories.

For a 180lb. person, sure, eat plenty of calories to keep going (and I agree, 1200 calories is not going to be nearly enough over the long term for someone that size). For me at roughly 65lbs. less (2/3 of that weight), the same or even a similar caloric intake is just a dumb idea. Then, take into account metabolic rate and body composition, and my own caloric requirements could change as much as 500 calories either way, if not more.

On another note, re: calories out and "negative calorie foods," protein has far fewer net calories than any other macronutrient, because it's just harder for the body to break down and absorb. This may be another part of the advantage of Atkins: a) the protein supports LBM, which in turn raises BMR, and b) digestion of protein significantly lowers the net calories from protein (total calories - calories required for digestion of protein), and eating more protein than many people on other diets ends up being fewer calories than we count anyway. Just a thought, and something I've run across a few times recently, so I thought I might add it.

I've heard caloric levels for "starvation mode" ranging from anywhere between 1000-1600 calories. I believe there is a starvation mechanism in our bodies, but I also believe, since no one seems to know for sure what that level is, that the caloric level for starvation mode is highly individual. Like everything else, I guess.

I don't mean to start/contribute to a calorie war or anything, but I do disagree with a lot of the generalizations that have been made on this thread. Perhaps because they were sweeping generalizations more than because what they said was wrong. It just isn't always right, IMO.