Is this anorexia?

[August21yellowbaby]

My sister from being a teenager has hated how "flat" she was. Probably around 6 stone until 18 then around 7 stone. Never looked bad, just very petite but a lot of my friends are too.
Anyway my sister has always tried to eat very calorific foods, complan shakes that she bought, ate takeaways a lot, she would have 4 meals a day, lots of snacks etc
Anyway there was a family fall out a year or so ago and I haven't spoke to her since as she was very nasty to my mum and myself
She is now posting on social media that she has recovered from anorexia? And I'm confused? I'm sorry if I'm wrong and offend anyone but I thought that anorexia was when someone is afraid of gaining weight and thinks they are fat? She has made an Instagram account about her recovery and says she was diagnosed at 10 years old but she definitely wasn't as obviously my mum would of known ??
Again if I'm completely wrong I'm sorry if I've offended I'm just confused