Is it always unhealthy to over eat?

Usually: If you are trying to recover from starvation or are training intensely (think michael phelps), then you may need to push the eating. An occasional feast won't harm you as long as it is balanced with exercise and leaner eating. Otherwise, yes overeating is unhealthy. It is responsible for so many of the health problems in the world today.

Sure: Overeating is not good at any time.