A baby gate works well for my mother-in-law, but my father-in-law is a little more tricky. I already have a lock on the refrigerator. Before anyone makes a negative comment - think about preparing food for the week for a family of six only to find the next day he has eaten all 25 yogurts and 25 or so frozen peanut butter and jelly sandwiches, not to mention what you planned on having for dinner that night or part of it and it has been all washed down with a gallon of milk - IN ONE DAY. So yes, eating is a problem. Outside of that, I need to be able to work in the kitchen without him coming up behind me, without me knowing it. Yes, we have hidden all the knives. Our last resort is a door - maybe a screen door. It would have to have some sort of lock. My problem is everyone else needs to come through there. Does anyone have any ideas on how to block off the area or maybe a specialty lock for a door? He is sneaky - he's already tried to cut the bike lock cable off with scissors or something.
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Do you folks live 'with you' meaning they have free reign to the whole house or do they have an apartment within your home?
IF they are somewhat separated, just buy a small fridge for their space and fill it with the stuff dad likes to snack on. Stock the family fridge with things right up front that he WON'T snack on (probably raw veggies & fruit, raw meat, whatever he won't just grab'n'go with.
This may take some time for dad to retrain the thought process of raiding your fridge...but if he equates new fridge with the snacks he likes, hopefully, he'll catch on pretty quick.
The baby gate concerns me--I am a shorty and I can't QUITE get over one of those, so having them up when we had 'groups' of toddlers and had to corral them--was fraught with MY falling. Which happened a few times, to the utter delight of the toddlers!
You can install a actual LOCK on a fridge. Dad did that to our 2nd home fridge--it's a pain to have to unlock it all day long, but it will quickly solve your problem.
A screen door with latches up high on both sides of the door may help to make a sort of visual block--again, everybody has to be tall enough to unlatch--and dad may well figure that out pretty quickly.
I'd say the baby-proof locks that go on doorknobs would be great, but anyone with arthritis (me!) cannot open those. I get the toddler I'm tending to open it for me (SMH over THAT)--and if you cannot quickly pop those open, they can pose a hazard if the person you need to get to is on the other side.
I don't mean to make fun of what is clearly something that's driving you nuts--but this reminds me of when my kids were teens. We had the home closest to the Jr High AND the HS. My house was literally FILLED with tweens and teens every single day. Gallons of milk, a batch of cookies were consumed EVERY.SINGLE.DAY. I had to make a grocery run every day. I also baked double batches of treats almost every day.
Small price to pay for being the KoolAid mom and knowing where everyone was at all times, esp my own kids.
Now I have DH who is WFH and raiding the fridge all day long. I put all the stuff I need for meals in the downstairs fridge and put the 'healthy snacks' in the upstairs fridge. It's helped, he doesn't snack on the stuff I need for meals.
If you do add a door: I remember the child-proof doorknob cases from when my kids were young...they spin without actually turning the knob unless one has the smarts and hand-strength to squeeze it tight enough to make it turn the knob.
Is there a way to keep your FIL more segregated in his own area of the home? What would happen if that area was locked from the outside so he couldn't wander into your area until you were ready for him?
Does he eat all night long as well? This is most likely a phase, as my aunt went through it as well (in terms of just eating constantly, although not a fridge raider or kitchen creeper). Is anyone in your home able to distract him or take him out for a ride while you do the meal prep?
Let us know if you get a winning suggestion and tell us how it goes. Wishing you success in keeping out your kitchen creeper!
A screen door would work and you could put a hook and eye latch up high where it would be out of view of dad. (people generally do not look up for a lock or latch)
One of the screens that they advertise for sliding doors might work. The screen can be pushed through, the 2 parts are magnetized and would be easy to get though in an emergency or if you just had to get out of the kitchen BUT it is a visual and somewhat of a physical barrier that might slow dad down a bit. (Put bells on it so that it would alert you if he starts to go through it.)
I almost hate to say it but this might be a case where dad would be safer in a facility where he would have supervision 24/7.
I went through a lot of this with my Husband. for a time I had to run a cable around all my dining room furniture because he would take the chairs to the deck and try to climb over a gate that I had installed that I had a combination lock on. (I had to drill out all the screw heads because he tried taking all the screws out with a screwdriver. (almost got them all out of the latch. ) I had to change the "up/down" opener on the inside of my garage with a keypad so he could not get out through the garage. I had to lock my keys in a safe or wear them so he could not get the keys and drive off. Had to lock the car so he could not get the garage door opener....
I was thinking of a numerical lock; the combinations could be infinite and it would be difficult for FIL to guess the right one. But it does slow down access in and out for others.
There are some other good suggestions already posted. I've never experienced this situation, so I'm just guessing and don't have any good insight into real life experiences in this kind of situation.