She seems like she's trapped in a loop, food, food food... is this normal? With dementia and Alzheimer's?

Just another terrible symptom of Alzheimer's, unfortunately. Here is a link to a useful article on the subject with some tips:

https://alzheimers.newlifeoutlook.com/alzheimers-always-hungry/

One of the many good things about Memory Care is the structured routine of 3 meals a day and 3 healthy snacks that are given to the residents. My mother's friend is one who's constantly hungry & forgets she's eaten the moment after she finishes. She's constantly asking for more food, but doesn't get it b/c everything is controlled in managed care, and they're not allowed to have food in their rooms. It may seem cruel to withhold food, but it's even worse to over feed them.

You should speak to your grandmother's doctor about possible medication. If she's eating her own vomit & dog food, chances are, she'll move onto trying to eat non-edible items as well, which is also very common with AD. When they live at home and even in managed care, they have to be watched like hawks. When I worked in Memory Care, we had a resident who snatched a hearing aid out of another resident's hand and ATE it!

I have two suggestions if you think your grandma needs to keep her hands busy. One is a fidget blanket you can get on Amazon which is very useful for some AD sufferers:

https://www.amazon.com/s?k=alzheimers+fidget+blanket&ref=nb_sb_noss_2

And the second suggestion is a baby doll. Many many AD & dementia sufferers very much enjoy swaddling, holding and 'caring for' a baby once again, as they once did in their youth. Even men. Some women will spend hours attending to her new baby doll and be happily occupied with that task. Perhaps grandma would enjoy that & stop thinking about the food cycle she's stuck in. You can get an expensive Alzheimer's doll on Amazon, or, a much cheaper lifelike infant doll on eBay which will serve the same purpose:

https://www.ebay.com/sch/i.html?_from=R40&_nkw=reborn+baby+dolls&_sacat=0&LH_TitleDesc=0&_sop=15&LH_ItemCondition=1000&rt=nc&LH_PrefLoc=1

Wishing you the best of luck redirecting your grandma & keeping her food obsession at bay.

Thank you all for your concern and your wisdom. I feel so bad when I have to tell her, "gram, you just ate 5 minns ago, i can give you anything else for another hour n a half ... then she will try to eat out of the garbage, or pick out of the dogs food bowl and I feel like I'm on a 100% lookout but what scares me is when I'm not there for twenty mins in the morning when I'm dropping of the baby to daycare, but I know this will all be okay

Before my gram went to AL, we would get stuff to make sandwiches so she could make one when she got hungry. They would satisfy immediate hunger, but not be easy to eat fast and not something you 'crave'. And something she didn't have to turn on the stove for. So she didn't overeat but had something she could make when she was hungry. Maybe try that approach? Get snacks that are filling, but not super tasty (like having a big cake or something they can overeat easily). Hopefully, you find a balance ASAP because I couldn't imagine trying to keep someone from eating their own vomit. :(

Would it be possible to split the 6 small portions to 12 even smaller ones?
“Forgetting” that they have eaten is common as is “forgetting” to eat.
Over or under eating is fairly common with dementia.
Do you control her liquids as well? You could, if it is possible, give her some juice when she says she is hungry. Maybe the flavored liquid would satisfy more than water would. And even more so if the liquid is thickened. A thickened liquid would seem more substantial than a thin liquid

My mother had that issue. She would eat a meal, then look for dessert, then a snack and then another snack. She would only eat a small amount, so it would never fill her up.
She refused any other activity, so it also might have been a search for something to assuage her boredom.

Mom is in MC now, where they serve three meals and three snacks.

Colleen

No answer from me, but we've just had a change that my son is ravenous and wants more food all the time. He doesn't vomit but is uncomfortable because we are having problems with chronic constipation. I'm very surprised at his sudden demands for more food all through the day. Wondering if this is an Alzheimer's issue.