Is going the day with under or a round 1000 calories bad?

You should be eating 1000-2000 cals a day. So i doubt that its bad for you. Under 1000 though is bad. If you want to lose weight try exercising. Not eating enough won't help you lose weight it will slow down your metabolism and your body will go into starvation mode. Oh and the amount of calories you intake depends on age, i think. :)