Bioperine, a standardized extract from the fruit of Piper nigrum L (black pepper) or Piper longum L (long pepper). It contains 95 percent of piperine. Bioperine is used in conjunction with other herbs or vitamins to increase their absorption and digestion to make them more effective.

Caffeine is a stimulant drug used for mental alertness and to accelerate energy and power. It is also used to delay muscle fatigue as it goes deep into the muscle tissues.

Synephrine or oxedrine is a drug derived from bitter orange or Citrus aurantium. It is an aromatic compound with the systematic name 4-[1-hydroxy-2-(methylamino)ethyl]phenol which indicates that it has an attached hydroxyl group at para position and a methyl amino group at another position. It is not one of those compounds on which an extensive scientific study has been done. However, it has some positional isomers such as the neosynephrine as well as other compounds. Studies indicate that it could act as a Beta-3 adrenergic receptor which means that if taken as a supplement it enhances the breakdown of fat to release energy and also increases heat production in the muscles.

Synthetic Guggulsterones, which is a form of orally administered guggulipid, which increases T3 (tryiidothyronine) levels in animal models. T3 is the conversion product of T4, which is produced by the thyroid gland. Thyroid hormone levels are closely involved in metabolic function. Increased thyroid levels can cause more fat to be burned and stored. While on a diet, the body responds by decreasing T3 levels, therefor decreasing metabolic rate. It is not known how guggulipid increases T3 levels. Guggul, also called guggulipid, is an ethyl acetate extract of the gum resin of the guggul tree.

Yohimbe- Basically a tree bark, Yohimbe is rich in pharmacologically active chemicals. It is commonly found in products developed for body building and enhancing male performance. The use of Yohimbe causes serious side effects too that include renal failure, seizures and in very rare cases, even death. Individuals suffering from low blood pressure, heart disease, liver or kidney disease, and diabetes should refrain from using any kind of Yohimbe supplements. Taking larger doses of Yohimbe can cause weakness, stomach disorders, fatigue, and nervous stimulation followed by paralysis. It is therefore important to avoid self-medication. Sometimes, side effects may arise even if small amounts of this supplement are taken, especially for prolonged periods. If you are already taking drugs for treating some health condition, it is best to avoid this supplement.