Under 1000 Calories but I'm just not hungry?

The problem with eating too few calories is that it slows down your metabolism, and prevents you from gaining lean muscle. Lean muscle boosts the amount of calories your body burns, thus boosting your fat loss. Your BMR is probably over what you're currently eating, and that's not good. If you're currently staying full but want to add calories, try adding good fats to your diet. Things like almonds or olive oil. Heck, a fourth of a cup of almonds is around 160 calories, and not very filling at all (plus almonds are a good source of protein and magnesium.)