That's owing to excess useless calories otherwise, notably carbs. Also, lifting some weights doesn't mean you're automatically slim, fit, and healthy. I see old beer guts lifting weights in the gym all the time.
You probably just made that up, typically.
Anyway, you have no idea of the exact amount of protein you're getting and your specific requirements.
Sheryl weighed in the other day, accurately as always:
So, yeah, protein powder's a good thing. Besides other times, esp. good after a workout. I always prepare a protein shake to bring to the gym with me.
Creatine's also good for you aging brains.