Why is not enough calories bad?

[Hopeful]

I've found sporadically throughout this forum that not eating enough calories is bad--sometimes I do fall short in how much I should eat, but I am wondering why this inhibits weight loss. I don't remember Atkins mentioning in detail about this in the book. He seemed to just go with the rule of: eat when you're hungry, and stop when you're satisfied.

[Natrushka]

Too few calories is bad if it's a constant issue. Eating below what your body needs to function (your BMR, basal metabolic rate) puts undo stress on your body, a stressed body does not burn fat, it hordes fat. This is the result of centuries of evolution and adaptation; it's something you must take into account. Centuries ago when food was scarce it was a signal that there was an impending famine and the body needed to conserve those fat stores to make it through times when food was unavailable. Our bodies do not know that famines don't happen in modern day North America, so when you restrict calories overly and for an extended period of time you are sending it the 'famine' warning and it's going to react accordingly.

Having a few lower calorie days isn't going to set this in motion, unless of course you have a history of very low calorie dieting, it generally takes weeks before 'Starvation Mode' as it is called comes into play.

Eating when you're hungry and until satiated is good advice. Unfortunately for LCers it can be confusing when you factor in ketosis, which robs you of your appetite at first.

HTH
Nat