The secret to Busta Rhymes' jaw-dropping weight loss -- he did what most people wish they'd done in quarantine ... focusing on heavy-duty training and bustin' a sweat every chance he got.
Celebrity trainer, Victor Muñoz, is the guy who guided the rapper through the program that made his bulging gut vanish ... and he tells us the key was pushing heavy metal. Seriously heavy, as you can see in some of Busta's training videos.
Victor tells us, Busta ripped through full-body workouts to strengthen his chest and cut down that belly fat.