The practice of consciously consuming more calories than your body requires as part of a weight training programme in order to help gain muscle. For bodybuilders, it is often followed by a period of ‘cutting’, in which someone will consume fewer calories in order to lose fat mass and increase their lean mass percentage.
The term ‘clean bulk’ might be used to denote a calorie surplus using healthier foods (such as high quantities of lean meat or fish).
The term ‘dirty bulk’ might be used to describe bulking which involves any and all food, whether they’re healthy and nutrient rich or not.