I had the opposite problem and some things that helped me were encouragement whenever I tried to eat. Do not try talking about it too much, it makes it awkward and makes it way worse. Try getting them a small gift and show your full support. Look out for them too, I know the distance is a bit annoying but when you see them do not say anything but if you see it is getting worse try explaining that you are always available to talk too. Just be open minded and understanding, they will appreciate that most <3