Fatness, or lack of it, has absolutely nothing to do with starting puberty.
Girls who are extremely thin through exercise, dieting or sometimes just genetics may delay puberty and can even cause the menstrual cycle to stop after puberty has begun. Girls who are overweight generally begin puberty (and menstruation) slightly younger than their thinner peers, but you do not need to gain weight to begin puberty (unless you are excessively thin). Puberty is programed into your genes and there is a very wide age spread (about 4 years) that is still concidered "normal" for puberty to start.
Yes.
During puberty, there are a lot of changes going on in the body. So loosing fat from the face is very common and normal.
Yes. Your body needs some amount of fat to develop, and if you have too much muscle (and little or no fat), you will not go into puberty.
The amount of fat in a person affects puberty. Fat holds on to hormones so the more fat someone has, the more hormones they can hold. Because of this, if someone is heavier due to body fat, they should hit puberty sooner than someone with less body fat.
active and have low body fat
when she goes through puberty and has a fat tummy
Yes, it's perfectly normal.
defanitely NOT When you go through puberty your body actually builds up fat and you look "fatter".
they get fat so fast because they are going through puberty they will eventually go through it if they eat properly
Essential fat in a female bodies are higher and her reproductive system requires more energy to function.
It may just be baby fat which you will start to see fading away after puberty. If not, i would suggest him exercising.
Most girls gain weight in various places during puberty. This is totally normal.