Guarana, derived from the seeds of a South American tree, is popular for its high caffeine content. It can contain up to 3.6% to 5.8% caffeine by weight, much higher than coffee. This makes it a common energy supplement. Caffeine can improve mental alertness and performance, especially in sleep-deprived individuals. People also use guarana to boost athletic or sexual performance, though there's no solid evidence to support these claims. Some studies suggest guarana, combined with other supplements, may aid in weight loss, but it's unclear if guarana alone is effective. The safety of guarana for weight loss is not well-studied. Because of its high caffeine content, it's not recommended for children, pregnant, or breastfeeding women. Always consult a doctor before using guarana. It's often added to foods and drinks but isn't found naturally in other foods.