Something like low blood sugar can also cause your symptoms of weakness/dizziness or even just being dehydrated. (Not
only do you need to drink a lot, you also need to be eating
protein to help keep the body' s fluids in check, it's a balancing of fluid and protein that keeps a person from becoming dehydrated. If you are active like you say, the chances of having a heart problem, aren't really high, so that's a good sign!