Couple pounds down, you compliment. Couple pounds up, shut your mouth it's just more to grab. Or a better sit on my face experience
I personally think compliments about weight loss aren't great either. Hear me out :
Some people lose weight due to illness, depression, etc. It sucks to get complimented on being sick. Some people actively want to gain weight but instead they lose it and the compliment could hurt their esteem, too, in this context. So many variations of why it's not great to compliment someone's weight.
I lost weight when I was younger because I ate one or two meals max per week for several months due to eating disorder - people congratulating me on the weight loss at the time were essentially saying "congrats on mistreating your body and having poor mental health".
Im back in the gym recently, and if I lose weight I hope people will congratulate me on being back in the gym (because Ive been saying I wanted to for a while) and doing something that makes me feel good, but not on the weight loss itself. I don't like compliments about weight in any context. They're weird and you never know how someone feels about their weight or how they got there in the first place!