I eat 1,000 calories a day. Is that bad?

aiave been eating that ever since I reached high school because i always thought a normal intake woul be 1200 and maybe if i could cut back 200 calories i could lose weight. Well as I thought i was losing weight [i.e 20 lbs.] my friend tells me that 1000 calories is not enough and that a normal diet would be 2000 calories or 1500 at the least so whose right? btw. I am a varsity tennis player who plays everyday.