Brain waves curriculum may start at what age?

Ihave a really high metabolism and only weigh 70 pounds (13 almost 14). people always ask me two questions: do you ever eat and how do you eat so much and stay so skinny. i am worried that a high metabolism wont me forever. what are some safe steps i can take to maintain being fit. (also, i already work out i am a dancer so i get cardio a lot)

What parts of the cardiovascular system are affected with atrial fibrillation?

So i have a lot of answers answered but it says i still need to answer more questions. why is it doing that? how many questions need to be answered?