Overeating can be detrimental to one's health in a variety of ways: there's more extreme cases, such as binge eating disorder and bulimia, but also simply eating too much and becoming obese results in health problems. As such, it stands to reason that, at some point, overeating would be considered haram.
Question: Is there a clear point where overeating becomes haram?
A question Why is smoking tobacco haraam? is answered quoting the Qur'an do not kill yourselves 4:29, and this logic seems to be applicable here.