"Bulking phase" refers to a period of time during which someone follows a specific diet and exercise plan to gain muscle and increase their body size or weight. Full definition
There are two main factors to take into account if you want to employ a proper clean bulking phase for maximum muscle growth and minimum fat gain. (seannal.com)
In fact, hard - gainers may find it difficult to gain weight easily, but with right knowledge it becomes easy and there is not much restrictions on diet if you are on bulking phase. (gainingtactics.com)
Usually, they start with bulking phase when they mainly build their mass, then they switch to a cutting phase when they try to burn the excess of fat to make their muscle more visible. (massgainsource.com)