Overview
Stimulants are chemical substances that can temporarily accelerate activity in your body. Stimulants can range in potency and are often used in both over-the-counter and prescription supplements and medications. One common use for stimulants is for weight loss.
With the withdrawal of ephedra from the U.S. market, companies producing dietary supplements for weight loss have replaced ephedra with other stimulants to induce weight loss. Many of these stimulants contain caffeine or are very similar to caffeine.
Caffeine and related substances suppress appetite and cause increased metabolism, thus causing the body to burn more calories. The increase in metabolism causes the body to produce more heat (thermogenesis). Most of these agents are probably safe in very low doses. However, side effects increase when these products are taken in high doses or in combination with other stimulants. Especially in high doses, stimulants like caffeine have the potential to cause nervousness, insomnia, increased heart rate, high blood pressure, abnormal heartbeat, and palpitations. Caffeine also causes psychological dependence and can cause withdrawal symptoms if discontinued abruptly. The increase in metabolism caused by these agents also makes body organs, especially the heart, work harder, which can lead to side effects over the long term. Supplements that contain stimulants should be avoided by women who are pregnant or breastfeeding and by individuals with underlying heart disease or high blood pressure. Many of these supplements have not been well studied and may have other serious side effects that are unknown at this time.
Types
Stimulants can be used both in supplements and in medication. Over-the-counter stimulants, such as caffeine and synephrine, are more commonly found in weight loss supplements.
According to the National Institute on Drug Abuse, prescription stimulants are a commonly abused medication. This is due to how easy it is to develop a dependence on the drug. Prescription stimulants have the ability to increase the levels of an important neurotransmitter in the brain called dopamine. As dopamine levels rise, a pleasant feeling of euphoria occurs. As these dopamine levels are sustained at a greater level over time, the brain can develop both a dependence on and a tolerance to the stimulant. Due to addiction concerns, all prescription stimulants used for weight loss are currently controlled substances in the United States.