I had a similar experience to a pp with a friend at university. Of course one would always hope to give someone the benefit of the doubt and try and read the situation and desist from commenting if you possibly can as it’s not your business. Absolutely agree with loving people warts and all if you can.
And it’s fine to say nothing if you don’t know a person particularly well and enjoy their company on a friendly but not deep level and they don’t appear to be suffering particularly severely and they have other friends and family support.
However, in my situation, I was very close to this friend and it became clear over quite a long time that she was in the grips of a very severe eating disorder. She was also quite an isolated international student from overseas.
Btw op, she was obsessed with food and cooking as well, and I think this is quite often a genuine enthusiasm but used as a front to cover up an ED, bc it’s a lot easier to not each much if you are the host and not the guest.
But over time you could see her get thinner and thinner and weaker and the way she never actually ate anything became clearer and clearer, and unfortunately she was always disappearing to the loo when she did eat a little, and sorry to say the excuses and lies became more obvious and in the end as a close friend, I felt obliged to say something and ask if she needed help because it was obvious something was seriously wrong.
In fact we nearly left it too late as she ended up in hospital for a long time and had many set backs. In the end, honesty wins out if you value a true friendship with someone and their life is in danger, same applies to drugs ie alcohol.