Healthy U ECYAHEALTHY U LABS ECYA BURN WITH YOHIMBINE HCL 50TABS) An ECY stack is defined as a combination of ephedrine, caffeine, and yohimbine. Ephedrine is well known as one of the stongest fatburners used by bodybuilders and dieters to kick start a weight loss program. Derived from the ephedra sinica plant, this natural alkaloid boost metabolism and suppresses the appetite. Yohimbine is an alkaloid from the bark of the Pausinystalia yohimbe tree that grows in