Can i use fiber like metamucil while on the hcg diet, if so, is powered or pill form the best?

Yes, but...: You may take Metamucil, in either form with your diet. However, the hCG diet has not been shown to be safe and effective. It is a diet with severe calorie restrictions, and can increase the risk of gallstone formation, irregular heartbeats, and electrolyte imbalances, among other side effects. I would not recommend this diet. There are safer ways to lose weight. Good luck.