Pretty ignoran writter, probably some fat chick.
It's not how many callories you eat, it's what those calories are made off. You can eat 4 sneackers bar and 4 cokes, and those 2000 cal would make u sicker than a 600 cal Subway meal. (Not that it's good for me but I live on 1000 cal/day on week days). My wife being the health freack, we have a diet of mostly Beans/tofu/wheat/soy and she became a freacking wizzard in taste like normal food. Heck I never thought I'd like a Tofu italian saussage, or a black bean burger 
but I have to give it up, very little taste loss for how good this stuff is for you compared to the heart attack equivalent.
Extreme calorie restriction hasn't been evaluated in humans, but there's a pretty good body of evidence in those poor laboratory rats that it extends life. Using the "starvation plus one kibble" diet their lifespan was extended about 50%.
Interesting study in humans: They tracked down people 90 years old and older living on their own in Boston, figuring that to live on your own you had to be pretty healthy. They found some things obvious: those folks didn't smoke or have diabetes, and they had good genes (family history of long life). Researchers THOUGH they'd find these people were healthy eaters, but it turned out that only half the long lived folks were. Instead, they tended to be small volume eaters of whatever food they preferred. Researchers would hear things like, "I like my steak and get potato with sour cream, but only eat half the potato and about 4 oz of steak. I get full, and I stop."
From the scientific standpoint, evidence seems to say that the AMOUNT is at least as important as the TYPE of food.
