In my experience smaller women balloon on anything more than 1500 calories. My mom, for example, doesn't eat any breakfast besides tea with milk, and eats a few fruits and small amounts of chocolate throughout the day as snacks, and bread with about two cups of vegetables, plus another cup of beans/lentils for both lunch and dinner. She's been doing this for as long as I can remember. Now this is by my estimation around 1100-1300 calories per day.
If we go to a family get-together or have a socially-loaded weekend, she gains weight. When she gets back to her regular eating, she trims down again. This is fairly normal for women of her size.
Starvation mode really kicks in, depending on your personal body chemistry and size, if you're only getting around 1/4 - 1/3 of your daily requirements for an extended period of time, like several days. Sure, if you only eat half your daily requirement, you might start burning off lean tissue to make up the caloric deficit (which is bad for fat loss), but you won't actually do any lasting damage of the kind the wrecks your liver and kidneys.
Hope this clears up the starvation issue.