Overdiagnosed : Making People Sick in the Pursuit of Health (2012) by H Gilbert Welch describes how diagnosing people without symptoms is a serious problem with modern health systems.
Over diagnosis is definitely a problem. Prostate screening and over diagnosis is accepted by many, perhaps most medical researchers as a serious problem. Screening in other areas is also seen as something that can cause real harm. Making abnormal physical characteristics diseases is definitely unwise. The incentives of the medical industry are also clearly on the side of over diagnosing.
However, where over diagnosis is the biggest modern health problem is pretty contestable. Lack of physical activity, obesity, dementia and other diseases might be seen by others to be bigger problems.
The book is definitely worth a read, however, it seems that perhaps Dr Welch has over diagnosed over diagnosis. The presentation of an alternative point of view would have made the book better. The book is nonetheless definitely worth reading.