This is a controversial practice where bodybuilders gain 30-40 pounds of bodyweight over a short period of time. The idea is to gain muscle by eating more food. This practice is controversial because the type of foods that are used to bulk up are usually of lesser quality and contain a lot of fat, thus it is a fairly unhealthy practice. There are also more competitions nowadays, and the demand for fitness models is quite high too, therefore it is to a bodybuilders advantage to stay in top form year round.