Many people believe that caffeine dehydrates you and that it is a dietetic. According to www.livescience.com caffeine does not necessarily dehydrate you. People believe that caffeine dehydrates your body because there is a increase in urine output. But a small increase of urine output has little to do with caffeine and dehydrating the body. Any increased fluid input will lead to an increase in urine output. This means water as well as caffeine. Coffee doesn’t make your body lose more water than is taken in. Caffeine in only much higher amounts will cause a significant noticeable diuretic affect. A study in the United Kingdom found out that people who drank 200ml of coffee vs 200ml of water had no difference in urine output and was not dehydrated. In conclusion, caffeine will only case dehydration effects when it is consumed in large quantities. But otherwise, caffeine does not cause any significant dehydration and should not be something to worry about short term and long term.