We are looking for ways to keep mom from eating everything (food). She doesn’t remember that she just ate and will eat and eat.

My Husband would eat anything sweet he could find.
I would keep snacks out that he could have without a problem fruit, his Crystal Light (he loved that stuff) and I would put 2 of his favorite cookies in the box on the top of the refrigerator where I used to keep a full box. (My Hubby was 6'4" with an arm span about the same!) He thought he was pulling one over on me by "sneaking" his cookies. All the rest of the sweets I kept in the pantry where he could not see them.
If you can get a small refrigerator for your mom's snacks and drinks that she can have freely. Keep the other stuff locked (yup ya gotta do it)
There are magnet locks for cabinets that do not even look like there are locks. You use a magnet on the front to open the lock.
There are "U" shaped locks you can use for the refrigerator If you have a white appliance even better she may not even realize the lock is there. Just say the door is stuck you have a repair man that will look at it later.
I do hope you have removed knobs on the stove and oven so she can not start it. With dementia it might not take much to try putting a bowl or other container on the stove. Some people I have talked to have even put a "master switch" for the stove so it can be turned on and off like a light switch so even if the knobs are turned on the oven / stove will not work.
Another option, if you do not have an open concept house is to close doors to the kitchen, lock them if possible.
Also you might want to try a large dark mat in front of the opening to the kitchen. Some people with dementia will not cross a black mat thinking it is a hole in the floor. (works for some not for others) And I even hesitate to suggest it because floor mats, rugs are a trip hazard. So if you try this get one that is heavy, has sloped sides almost like a commercial mat that you would see walking into a store.

You may have to really hide or secure the food you don't want her to have away, but, I'd be sure to put good replacements so she has easy access, like celery sticks, carrots, sliced cucumbers, etc. After a while, my LO had no idea that food was in a container, if she couldn't see it. She even forgot there was food in the fridge or under foil. It had to be visible under clear plastic and sitting in front of her. I think there are various stages where the food is involved. My LO was one to stop eating and lost lots of weight.

I'd also caution to remove cleaners and medications from her reach. Sometimes, they may ingest things that are not food, not realizing it.

How many incidents like this?

Any involving anything more calorific and more disastrous than strawberries and a piece of melon? - how big were the packages?

The home health care nurse visits every two weeks. On the last occasion, the nurse observed that your mother had gained 3 1/2 lbs. Well, 3 1/2 lbs = a bowel movement and a large soda, roughly. It's not conclusive evidence that she's on the road to ruin.

The forgetfulness about having eaten does seem to be a distinct phase (my key memory about this was mother's plaintive "are we *having* supper tonight?" while I was, literally, still clearing the dining table); plus your mother has health issues which could be made worse by poor diet, so of course you and your sister are concerned, quite rightly.

But I wouldn't overreact, it's not like trying to manage a child with Prader-Willi syndrome. Your sister could try:

leaving suitable snacks and "nibbles" more easily available so that your mother sees them first
providing eye-catching diversions, e.g. a kaleidoscope lamp that gets switched on after dinner; or brightly coloured cat toys, get him involved, why not?!
placing alerts on the fridge and store cupboards. One client had a pig alert that made an "oink-oink-oink" sound whenever you opened the fridge door; lunch calls to him were great fun!

I'm sure your sister doesn't and wouldn't do this anyway, but arguing with your mother and telling her she can't be hungry (she is hungry. Hunger is a sensation, not a matter of arithmetical fact) a) is unkind and b) won't work.

Change the subject.
Offer something nice, low calorie and preferably time-consuming to consume.
Embark on an activity - balance exercises, bath time, clothes folding, silver polishing - anything!

Kudos to you for your praise for your sister, by the way. Only, remind her that she is only human, she can only do her best, and having a nap after dinner doesn't mean she has failed :) Hugs to both of you, and your mother.

Does the cat even like gravy???

If your mother is beginning to have signs of dementia, it may get worse. The suggestion to put a lock on the kitchen door seems like a good one, as there are dangerous things in the kitchen (fire, knives, etc.). When my mother (with dementia) moved into a memory care facility, they took away her knives and scissors and didn't let her near a stove. Previously in her own apartment she had done some incorrect things with the microwave (put metal in it) and blew it out.

You have received a lot of great advice. As a caregiver for my dad who passed 6 years ago and now my 95 year old mom who lives with us I would suggest you make sure the stove and oven can not be turned on. We have a combination range and oven and I keep the breaker off unless I am going to use so she doesn’t turn it on and forget. As a lone caregiver for my mom I appreciate you praising your sister for taking great care of your mom. It has taken me years to realize everyone just doesn’t have it in them to be a caregiver.

In some cases it wouldn't be as critical...but you're dealing with blood sugar issues here. We are dealing with a more minor form of this...and it's getting to the point of considering a lock on the fridge. Yeah, they make them...and my co-worker whose grandma had the same thing going on...they did put a lock on the fridge. Grandma got pissed the first time she went to open it and couldn't, but the it wore off and she adapted. It's either a lock on the fridge...or a lock on the kitchen door to keep her out, which may be easier and less damaging. The adhesive on the fridge lock I found is considered permanent. It's very strong. It's hard to explain but two loops of high quality cable meet and you run a small lock through it. I got the version that didn't come with a lock so I could get our own, and got a small luggage combination lock to loop through. That way you don't have to keep track of a key that can go missing or not be around when you need it. We're actually using it on big trash and recycle bins because I have emptied and gone through them one too many times looking for hearing aids and eye glasses...My mother grazes constantly through out the day salty snacks, sweets, grapes, olives...pop...she's not heavy at all...They make some great child proofing stuff that will allow you to lock the cupboards. We pulled the knobs on our old oven and stovetop; she was letting the garbage disposal run and run and we hooked up a surge protector (heavy duty) so even if she turns it on at the switch the surge protector keeps it off. I'm also thinking of possibly getting one of those small dorm/bar/hotel sized fridges for the family room where only healthy snacks will be left for her...watch for the cupboard locks that have a diversion button...they think that's how to open it but it really opens when you squeeze the sides...

My mother is in her 3rd year of Alzheimer's. She used to raid the fridge and finished a full bottle of OJ. She would take the sugar jar out of the kitchen cabinet and started eating spoonful at a time. Now, we have locks on the fridge, the pantry, the cabinets, etc.

I would think most kitchens won't have a door to lock to keep anyone out, so the next best thing is to child-proof it.

NOTE: even older microwaves have a built in safety feature: press/hold the stop/cancel button for about 3 seconds to lock the control panel. Repeat to unlock. Nice, easy, quick and simple!

Newer models of appliances (my stove/oven and washer/dryer) all have the same control lock feature. I had to use the washer/dryer ones because the cats would sometimes turn the panel on when jumping up onto them (never did start either, but why wait!) For older models, the oven generally has a locking mechanism, most have removable knobs, which should deter use, otherwise, unplug or turn the breaker off.

Cabinet locks have been around for a long time. Many options, most easy to install/use. As others noted, this is key for safety beyond just restricting food access (knives, other utensils, cleaning products, etc.) Better safe than sorry!

I do like the idea of getting a dorm-size fridge and stocking it with various low calorie nibbles (carrots, celery, think of the various veggies in a dip pack, minus the dip, small amounts of other fruits, veggies, beverages - esp water) For the most part, many people could reap benefits from this too - healthier, low cal foods. Keep any "treats" like cookies, snacks, etc to a minimum, but certainly very small amounts can be put in containers so the person isn't totally shut off - it's nice to have a "treat" once in a while!

Same concept for those with pets - keep the foods in a locked location, allow minimal access to "good" treats the person can provide to the pets! Freeze dried chicken treats would be something that should be okay, under moderation!

My mother was already a bit too heavy, but within a year of moving to MC, she gained 20#! Most of that was likely due to the daily ice cream bar for dessert... I haven't really put a kibosh on this, as you can't explain the weight issue (She points out others, but doesn't consider her own weight. She checks size on anything new brought in, Oh, that's large I usually wear a medium,... not any more mom! She even will point to my mid-section asking if I'm preg, but it is only my hoodie pocket with mitts in winter!) I also figure why bother. At 96 1/2 with dementia, and refusing now to stand/walk, not much to do. They do provide mostly good meals, and the desserts are pretty small. Reality is she won't be exercising or losing that extra weight, restricting intake isn't likely to reduce her weight either. Given your mom has to worry about diabetes, many suggestions given could help:
- restrict access to the "bad" foods
- allow more access, but don't over do it, to good foods
- restrict access to everything in the kitchen
- don't forget bathroom cabinets and laundry area!
- find ways to occupy her time, such as folding laundry, sorting items, playing with the pets, etc.

Sometimes we can redirect them, get their focus onto something else when the food topic comes up, or defer it saying it is cooking, it'll be ready in a while.

I read the topics and answers and they are helpful. Sometimes, however, they make me extremely cautious about the days that my spouse will be going through. We've had 10.5 years of a "honeymoon" dementia/alzheimers and now he is declining. I have a belief that anytime you can know things ahead - it will prepare you somewhat for what happens in the future.

May each of you find strength, courage, patience, hope and peace in your journey(s). I'm the one wanting to eat everything the last six months since things have become more difficult. However, my LO forgets he eats, and then wants to eat again. Thanks to everyone for helping each other. Be safe.

Install locks - akin to childproofing - as if she's not realizing that she just ate, what else could she ingest?