I do understand the basics of eating disorders & I know that my family is riddled with undiagnosed MH issues. Yeah, we don't talk about them.
So here is what I know.

My sib has been heavy a great deal of her life. I'd say close to morbid obesity. So she had some band surgery & a yr afterwards she lost A LOT of weight bragging about it on FB, but not telling others how she did it. Then she had a tummy tuck & focuses on all this extra skin she has. Telling her it won't just go away....doesn't help.
I thought she was feeling more confident in herself.
A yr ago she started putting weight back on. Then I noticed last spring she had a diet drug script on the counter & she told me she goes to a "weight management dr."
Now my other family members are discussing an "invervention" bec she's too thin. They guess close to....under weight numbers.
Talking to her, via text, she's of course fine, but her older DD tells us she won't eat with them anymore, drinks only broth & eats veges & wont tell anyone her weight. She seems to be hiding her weight loss, wears baggy clothes & is still not happy how she looks.
I stated to other family members that it doesn't seem to be on the surface about food, but about the control of it. She's 50 yrs old & I know she's not fulfilled in her life or really happy. My eldest sib said....we'll force her to get on a scale & keep track of it!
Yeah that's not very helpful...I think.

I guess I understand how eating disorders start when people are young. But I'm not sure what's going on here bec of her age. I feel like I'm missing something. Everyone just suggests that she eats more...& I know that's not going to make a difference.
Any help?
Thanks!