The term metabolism refers collectively to the processes in your body that work to either convert or use energy, according to MedlinePlus. Metabolic functions include blood circulation, breathing, body temperature control, muscle contraction and digestion of food and nutrients. If the metabolic processes that use consumed energy function at a higher rate than usual, it is believed this can aid weight loss. Therefore, various diet pills are available that claim to boost metabolic rate.
A range of diet pills that claims to boost your metabolic rate -- and therefore the calories burned by your body -- is commercially available in the United States. According to a report at MayoClinic.com, ingredients of some of these pills bitter orange, chromium and green tea extract. Because diet pills are not generally regulated by the US Food and Drug Administration, it is difficult to assess the function or safety of such products. Country mallow, also know as heartleaf, is considered to be unsafe and has been banned by the FDA.
Metabolism-boosting diet pills typically function by containing stimulant substances -- such as caffeine, or green tea extract -- or substances believed to have a stimulant-like effect. MayoClinic.com reports that other ingredients in over-the-counter diet pills, such as bitter orange, are selected for their believed stimulant-like effects on your metabolism. Stimulants typically function to speed up your digestion of food, and also your breathing and heart rates.
Dietitian Katherine Zeratsky, N.D., reports that although it is widely believed that stimulants such as caffeine can boost metabolism and therefore aid weight loss, there is no conclusive evidence to prove this. Some studies indicate a possible link between caffeine consumption and slightly boosted weight loss, but many of these studies are either poor quality or conducted on animals rather than humans.
A report in the March 2009 issue of the "Journal of General Internal Medicine" discusses the possible harmful effects of amphetamine-based diet pills imported into the United States from Brazil. Diet pills based on amphetamines used to be freely available in the US, but have been banned due to negative health effects. In this study, two patients using imported diet pills were found to have symptoms caused by the diet pills' stimulant content. These symptoms included chest pain, palpitations, insomnia and headaches.
According to MayoClinic.com, stimulants intended to boost metabolism may cause other problems such as anxiety, nervousness and insomnia. Caffeine, for example, may also act as an appetite stimulant, which could negate any weight loss achieved through its temporary metabolic boos. Many of the stimulants in supposedly metabolism-boosting diet pills are not safe for everyone, and may exacerbate existing health conditions. You should always consult your own doctor for individualized medical advice before making dietary changes or taking diet pills.