I have a friend who tends to bring her own food and decline most things our group of friends offer. She eats
very healthy, whereas the rest of us are more normal. I, and from what I've gathered other people in our group, don't exactly "look down" on her for her eating choice. But we are saddend when our food offerings are not accepted - it is a joy to cook for your friends and having the gift of food refused can feel like your signs of affection are being refused. We
know that she is not refusing
us. But there is no denying that happily accepting a cooked meal as is, rather than picking through it discarding most parts of it as "bad", is a smoother social greasing.
Even if you/my friend/whoever tries, for the sake of the own health which objectively is commendable, to avoid making eating a social thing - it still is for the people around. Sharing a meal is a bonding thing and refusal to partake could be seen as a refusal to bond ... (Also, sharing in "forbidden acts" like pigging out on cakes together makes a strong bonding experience. Showing your weakness, for ex for chocolate, and having the other person accept that makes friends. Showing your weakness and having the other person confirm that it indeed is a weakness than can be overcome, only that you, you weak weak chocoguffing piggy, haven't, doesn't make friends in the same smooth manner ... )
Just providing the "other side" of superhealthy eating versus normal "aware" eating habits and some group dynamics based on my observations.