My teenage son acted up so much that I'm not only grounding him, I'm withholding food from him for 3 days.
That's you're son! Would you really withhold food from him for three days?
Yes. He was very disrespectful and this behavior needs to stop.
That seems like a massive overreaction to me. You can't deprive someone of food without a good reason. You need to think of a more suitable punishment!
It's the punishment he needs, he needs to understand that I won't tolerate this behavior from him anymore.
I think you should talk to a therapist about the best way to get through to your son. Withholding food is abusive and it won't make him respect you. This would just further damage the relationship between the two of you.