A natural substance. Biomarkers are a natural substance in the body that can be measured. Under certain conditions the level may rise and be clinically relevent the heart has biomarkers like troponins that go up with muscle damage. This would indicate a possible heart attack.
There are several. There are several factors including ghrelin and also Insulin metabolism that are important.
None. So far, as far as I know none have been found that could be validated. So stop eating so much. That may help.