Application warnings

I started using the Lose It! app again. Mostly to hold myself more accountable on weekends, but since I started logging last weekend, I figured I'd use it throughout the week. I set the "weight loss goal" at 2 pounds per week because I know that's the most it will allow you to select. It claims at my height and weight I need to net about 1,200 Calories a day to lose weight at that rate. It's probably not a far cry, but I know I do better around 900-1,000 (but this still generally doesn't result in a 2 lb per week loss, so I don't know what they want). Seeing the numbers has made me more restrictive, which is great but I was surprised when the first two days that I logged a net Calorie intake of under 800, it congratulated me on my self-control. The third and fourth days with my net Calories being 920 and 593, respectively, it didn't say anything. Then yesterday when my net Calories for the day were 640 it popped up with a warning that I apparently should be eating at least 1,200 Calories per day just to function and survive. I could get on board with 1,000, but 1,200? Nope. No way. And really, I'm consuming over 1,000 Calories per day, I'm just running off between 400 and 700, so I'm eating quite a bit, but getting ride of it, because I am still fat and I have to.