There is evidence that reality TV can harm your mental health, but that doesn't mean it's completely bad or good. According to UK Mental Health Foundation, "Almost one-quarter (24%) of 18-to-24-year-olds told YouGov that reality TV makes them worry about their body image. Our poll also suggested that the same young people are already more vulnerable than older adults to body-related distress, with nearly one-quarter of them (23%) also saying they had had suicidal feelings because of concerns about their bodies."
This shows that reality TV can be bad for your mental health, but it's not black or white. There are plenty of people (including myself) that enjoy reality TV, and it doesn't affect everyone's mental health in a negative way.
Source: https://www.mentalhealth.org.uk/explore-mental-health/blogs/harsh-reality-reality-tv-and-mental-health