cutting cycle
More commonly known as "dieting". This "cycle" usually follows a "bulking" cycle (where one weightlifts to gain mass/muscle at a rapid rate). The "cutting cycle" sheds the body of excess fat so muscle definition can be achieved.
"I've gained about 10lbs of muscle during my last cycle, but I still have about 20lbs of fat on me, so in a week I'll start my cutting cycle so I can lose the fat and see the muscle more easily."