Caffeine is extracted from coffee and tea during the process of decaffeination. Caffeine Anhydrous can be produced from dimethyl urea and malonic acid. It stimulates the central nervous system, enhancing the focus, concentration, and alertness, and warding off drowsiness. It is a mild diuretic and can also increase the metabolism. It increases the energy level and reduces fatigue. Aside from increasing mental alertness, it also helps in maximizing weight loss training. It stimulates the metabolism that helps the body to burn fat faster and uses the fat as energy. It also provides physical energy and delays the onset of fatigue.

Citrus Aurantium, More commonly called "bitter orange", which is taken from unripe oranges. Research shows that citrus aurantium can increase the metabolic rate without affecting heart rate or blood pressure, breaks down fat, burns calories and may act as an appetite suppressant.

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 is a tree that grows in different parts of Western Africa. Active compounds called alkolids are present in its bark with Yohimbine being the principal alkaloid. Yohimbe bark extracts are available in health food outlets. You can also buy it online. These extracts are promoted as a product that increases sex drive and for the treatment of erectile dysfunction. However, there is proof of their effectiveness. Most studies are concerned with the drug Yohimbine and not herbal extract Yohimbe. The side effects of Yohimbe include anxiety and dangerous increase in blood pressure.