Guarana is a plant that grows in the Amazon. It is best known for its berries, which are used as an herbal supplement, usually marketed as a weight loss product or energy supplement. It is commonly used in soft drinks and energy beverages.
Many people are not aware that the active component of guarana is actually caffeine. The berries of the plant have a high caffeine content (even more than coffee beans). Caffeine works as a nervous system stimulant and as a diuretic (a "water pill").
There is a lack of scientific evidence to support a conclusion that the supplement is effective for weight loss. No adequate research studies have been performed and published using this substance for weight loss.
Currently, there is no established safe and effective guarana dose.
More research is necessary to determine an appropriate dose.