I get a lot of strange compliments on my weight and I do not think I have ever been able to sort out an appropriate response.
I get compliments about my weight (and questions on how I stay so thin or lost weight after babies). I don't do anything specific for weight. I do try to be healthy and active, but that is totally about feeling good and having good energy, not about weight and frankly, I don't think it impacts my weight. I eat more when I am active, and naturally seem to eat less when I am not. I don't change size much when I am working out or not. I merely change the way my body feels, moves, posture, etc based on muscle tone. I am not more likely to get this compliment if I am working out 7 days a week or not working out at all for months and months. People focus on overall size it seems, not tone. The truth is it's genes. Everyone in my family loses baby weight easily, stays thin, etc. Lifestyle has absolutely nothing to do with my weight, never has, and maybe never will. It is just genetic luck in my case I believe and I happen to have been born a person who loves healthy foods. My mother says I was the easiest child ever to feed and literally used to beg her to make me a whole pot of Brussels sprouts. It is really how I prefer to eat for my taste. I am not some awesome machine of will power. I love vegetables more than sweets even. I don't like people thinking this is why (because people do comment if they see me eat that "this explains it"), because I have siblings that eat all fried and greasy and whatever and they are just as thin as I am and always have been. I do not think my food choice is why I am thin.
When I say "that is just how it is, I don't do anything" it is met with either total disbelief like I don't want to tell them the secret, or it makes me feel like it comes off as braggy or awkward no matter how I say it.
Now if people simply told me I looked good, then that is fine. I feel no weirdness there. It's when it worded differently I feel awkward on what to say. I can give you an example I have heard in various variations that is one I particularly disdain.
I just wanted to tell you how great you look after having kids. So many moms today just let themselves go and you look as good as you did before the babies. You took the weight right off.
I hate this because it compliments me on something I actually didn't do while insulting the "average mom" which I want no part of. I simply do not know what to say that makes sense to such a remark in passing. The person saying it also clearly always thinks they are paying me a massive compliment. I don't feel complimented at all. I feel like I was used for you to be able to spew out that you have a low opinion of the "average mother these days" and what I want to do is set you straight that your opinion on my weight is neither valuable nor warranted. I can tell you I have had this said to me in variations by anyone from teen to elderly and sometimes even other mothers, who themselves placed a high priority to get in shape, which is great for them if it's about them but not great if you want to compliment me while calling "other moms" lazy.
Honestly I really usually don't reply. If I am walking, I keep moving. If I am stuck, like in conversation, I literally just smile and ask if they can excuse me and insert something here like needing to find my kids, spouse, use the bathroom, get home, etc.
TL;DR - read the quote. I do not know how to respond to a compliment about my weight because I didn't lose weight on purpose and I don't like how complimenting me gets blurred in with insulting other people who are not as thin and I am asking if there is a good way to respond to that type of compliment which I actually think is more a comment versus compliment.