Although it might sound like a dream, living on coffee alone is not so wise. There are some positives like reducing the risk of Type 2 diabetes and some cancers, but that's just with regular consumption. Like two or three cups a day. Going on an all-coffee diet leads to excess amounts of caffeine and causes headaches, nausea, restlessness and muscle spasms. Overdosing on it can even lead to more series problems like comas, trouble breathing, and cardiac arrest. So go ahead, enjoy your espressos and americanos. Just remember to keep it in moderation.