If you eat a shitload....Your gonna put on mass alright, plenty of fat too....Why not make it far more precise....When you are cutting you try to lose about 1lb per week at 500cal deficit. Same principal goes for a lean bulk, eat about 500 and try to get a 1lb a week. No one said don't eat, but you can gain with far less calories than you think. If you are in a calorie surplus you will gain. Now there's other factors like somatype that are involved, but that varies from person to person.