Do you have to have not one ounce of fat on you to do gymnastics?

[gymnasticsgirl]

I am an 11 year old girl gymnast from Australia and my mum says that in America if you have one ounce of fat on you, you will not get picked for the team. Well I'm in Australia and I don't know if that happens. But the thing is I am not skinny. I have lots of ounces of fat on me. Is that bad?