Uncertain. The research evidence is very weak either way. Relatively few studies have looked at the link between chocolate and acne (or milk fat and acne), yet all of them have serious problems with their methodology. Some trials were too short to rule out natural cycles of acne flare-ups, others had too few people, or didn’t have proper controls. One study simply involved a questionnaire asking people to recall what they had eaten while in college, years ago, and how bad their acne had been. While there is some evidence that diet can exacerbate acne in people who already suffer from it, there is no clear data to pin down whether it is caused by fat, sugar, hormones in milk, or cocoa. If chocolate does cause spots, the effect seems to be very small.