Believed to increase metabolism and fat oxidation, green tea is popular among diet enthusiasts because of its link to weight loss. But green tea has many other health benefits that suggest it should replace coffee in any health conscious person's lifestyle. By reducing the risk of thrombosis, green tea might help reduce the risk of heart disease. Green tea has been used in traditional Chinese medicine for many years, and it has been used to treat rheumatoid arthritis, to boost impaired immune systems, and even reduce rates of tooth decay by eliminating dental plaque. Green tea contains lower amounts of caffeine than black tea, resulting in reduced rates of insomnia.