Does overeating excess calories and weightlifting cause hair loss?

Excessive eating does not cause hair loss.  Malnourishment can cause hair loss.  Weight training is not linked to hair loss. Androgens to increase muscle mass can accelerate hair loss.  Are you on any supplements?  These generally do not cause hair loss, but study the ones you are on.  Yes, an increase in DHT can accelerate hair loss in men, but this is not going to occur from weight training alone.  If you are concerned, check you blood levels.  

No, these are not a trigger for hair loss in most individuals. Calories are great for hair and weight lifting does not trigger balding.

Increasing calories does not increase the degree of balding or hair loss, but the use of many weight supplements sold on the market have steroids in them and this can cause hair loss. If you are stressing out over it, this can also cause hair loss