My boss commented about my weight gain. Not sure what to do.

I (23F) work at a small insurance brokerage. I've been with the company for a year and I did gain weight over time. I'm trying my best to lose it and currently on a diet. My boss is known for having no filter so I was unfazed when he called me Garfield during a lunch meeting. Now, he is being way more hurtful with his words. He recently said, "I wonder how much weight you've gained since last year. You used to be skinny" and "I hope that's muscle and not fat". I told him that wasn't nice and he laughed it off. My coworkers witnessed everything and I told them how upset I was. My supervisor told me to suck it up and that it wasn't a big deal. Am I being dramatic? What should I do?

Small update: Thank you everyone for giving me great advice. I realized that I am being harassed and I am writing down all the incidents. I don't want to take legal action because my coworkers were not defending me when it happened. They made up excuses for his behavior and I don't think anyone there will take my side. I am privately looking for a new job and scheduled an appointment to speak to HR tomorrow. Hopefully they will transfer me over to a new office and speak to my boss about his behavior.