Bodybuilding is all about appearances. Nobody cares how much you can lift, how fast you can run, or how many pull-ups you can do. All that matters is that you maintain a well-balanced, muscular physique that is lean enough to really show off your musculature.
Few bodybuilders, if any, maintain the same physique all year round. They will be at their leanest (anything down to just a few percentage points of fat) going into a competition, after which they will put a lot back on.
You need to do this just to be healthy.
What’s required of you
You will need a caloric deficit to shred yourself down to the kind of body fat percentages required of you at competition level. However, you will generally need a caloric deficit to build muscle.
Because of this, bodybuilders typically cycle through mass gaining (or bulking) and fat cutting phases.
You need to know
Before cutting or bulking, you will need to know your own caloric needs. This is easy enough to work out using an online BMR calculator. Be sure to factor in the amount of activity you generally perform on any given day.
The bulk can last for weeks, months, or even years. During this phase, bodybuilders will eat high-calorie diets- they will be in a caloric surplus.
A caloric surplus of 500-1000 calories per day is quite common. This should lead to 0.5-1kg of muscle and fat gained per week, though actual amounts will vary greatly depending on the bodybuilder’s training history and genetics. Generally, the newer a lifter is, the more muscle they will be able to put on in any given time frame.
A typical bodybuilding mass gaining diet will be rich in protein and fat. This will enable the bodybuilder to elicit as much hypertrophy as possible, growing as much muscle mass as they are able.
During this phase, high-intensity lifting will be required to maximise the gains made.
As some fat will likely go on during the bulking phase, and as a bodybuilder will want their body fat levels to be as low as possible for competition, a cut will be needed.
This will mean a caloric deficit. A deficit of 500 calories per day (or 3,500 per week) will allow for the loss of about 0.5kg in bodyfat. A deficit of 1000 calories will accordingly lead to a loss of around 1kg. Much more than this is inadvisable, as atrophy (muscle loss) will become a risk.
During this phase, training still needs to be hard. This will allow for the retention of as much muscle as possible during the cut. Protein intake should remain high, and fat intake moderate, with the majority of the cut calories coming from carbs.
A typical cut can last weeks, months, or even years. However, a longer duration cut is only advisable for somebody who is obese. Most bodybuilders will go for a period of weeks to months to achieve the results they want.