I guess men can be pretty to each other. When my husband and I regularly went to meetups together, he said he would get this look from the guys who were checking "You're with her??"What is the purpose of your concern and your post? Are you afraid of her cheating or dumping you? Be honest because context matters.
There is some calculus here. If she gained 80 lbs and has returned to her previous weight and level of attractiveness AND you have remained at your level of attractiveness and your market value and you two are now back to similar market values (assuming you were similar to begin with) then this is just a matter of her getting back in her stride and a matter of appropriate vs borderline inappropriate conduct on social media.
However- if she is now actually more attractive and sexy than she was when you got together and you have now gained lots of weight and she is notably more attractive and of higher market value than you, then you do have cause for concern here.
A quick google search of “post weight loss infidelity” or “post weight loss divorce” and you will see there can be reason for concern here.
This is something that the people who have the weight loss surgeries often contend with. Frequently both are overweight when they get together initially and then when one loses 100+ lbs, that puts them in a higher league and it’s a risk for the other to get left behind.
80 lbs is a significant loss and good on her for taking charge of her health and vitality.
But your level of risk here depends a lot on you and your market value. Are you two relatively equal in attractiveness now or is she significantly higher than you now?