Exactly. It's the height of rudeness to comment on someone's eating, what they're eating, how they're eating, how often they eat etc.
I have had to endure similar shitty comments in the past from people who think they're funny, or that I NEED to hear their comments about my eating... People I know - and people I don't know. Comments like 'fucking hell, you hoovered that up' and 'Jeeeezuz YOU know how to put it away!' and 'never seen a woman eat so much!' (from men AND women!) Always when I wasn't even eating that much. It was just a way to put me down.
One woman who used to work with DH took a disliking to me for some reason... We went out on colleagues nights out 4-5 times a year, (his colleagues) and sometimes we had a meal, and she would say 'Bloody hell Ginger, you won't be able to get out of the door if you eat much more.' and 'watch that waistline ginger, you'll need your jaws wiring up if you're not careful.' Again, when I wasn't even eating a lot.
A couple of people said 'blimey Helen, no need for that,' including DH - but she'd just say 'oh I'm only joking, Ginger is so sensitive!' I hadn't even complained (although I was fucked off) it was a couple of others telling her to shut up and stop it. I rarely eat outside of the house now because of this - except in the privacy of the car... (and occasionally at cafes and restaurants with DH.) I also refused to go on any more employee nights out as long as Helen is there after the third time she said something to me. Luckily she left 2 months ago.
Also, I was out one day at a shopping centre 20 miles from me doing some Christmas shopping last November, and I had only had a small bowl of cereal at 7am and it was 2pm. I had a cheese and cucumber sandwich from a local eatery, and was tucking into it on a bench, and some middle aged man I didn't even fucking know, sat next to me and said 'you'll get ever so fat eating that!' I just looked at him for 3-4 seconds, rolled my eyes and moved to another bench. He looked shocked that I had moved and said loudly 'can't say anything these days, world of fragile snowflakes I swear.' You don't have to be a fragile snowflake to not want some random arsehole coming up to you in public telling you that you'll get 'ever so fat' from eating a sandwich!!!
I did want to say 'who the fuck do you think you are commenting on some random womans lunch and telling her she will get very fat by fucking eating a sandwich for lunch you fuckwit?' But I ignored him, carried on reading my magazine, and felt grateful I wasn't married to the opinionated arsewipe...