I think if you value the friendship up to now, it would be great if you were able to 'suspend offence'
That doesn't mean you can't revisit the conversation and explain in our culture it's rude to comment on appearance.
I have a gem for you op. I am fat (currently losing, but it's not going away overnight) and I volunteer at an English conversation group attended by a mix of refugees and asylum seekers.
Each week we start with an ice breaker, so I was chatting to a stick thin man from Eritrea. He was supposed to ask me three questions about myself. He started with 'do you go to the gym?' Now the thing is, I've got health problems that have prevented me from using the gym and I'm recovering from a major surgery, but I didn't want to go into that, so just paused briefly before replying 'no'
'Well, you should,' replied the man, with a kindly smile, 'because you are very fat. You should go to the gym, and then you will be thin, like me.'
I had two choices in that moment - laugh or cry, and I chose to laugh. I was gutted but I understood he did not mean to be rude or hurtful.
'Next question.... Do you go swimming?'
I will fully admit to bawling my eyes out when I told my Dp the story that night. 