I grew up in a house where food was not taken unless asked for, in case it was planned for a meal. I married into my DH family

These people eat everything that isn't nailed down!
I don't understand, and I am always aggravated with my DH. His attitude is if it's in the house, I will eat it if I want to do so.
I'm like, look, I sat down, inventoried our kitchen and then made out the two week shopping list. When you eat it all up, I don't have what I need for meals.
He has now spread this attitude to our teen boys, everyone knows that growing teen boys will even eat the nailed down food! They always say, " But I asked Dad, and he said sure, eat it, we can always buy more--NOT, once I spend the money, uh, duh, it's gone until next payday.
Yes, OK, right, where is so and so?, I need it for dinner. Oh Dad said we could have it.
I don't understand the lack of self control either, yet, somehow. I've raised piglets too!
I have put my foot down, hidden items, not replaced them, and gone without- nothing phases these people for Pete's sake. Eat, eat, and eat some more.
So, for those who don't understand, some of us have to hide certain things. Mine is snacks and candy. The toddler is potty training himself- 5 days and he has mastered it all. It only took a bag of M&M's- two at a time for each success!
If I hadn't hid the M&M's, they wouldn't have been available for the toddler. I use a box in the garage- it's red, just like all of the other Christmas/holiday boxes, however, IT HOLDS A GREAT SURPRISE- all the "stuff" that I need to hide.
We use the garage for storage and don't even go out there for garbage control or toys- strictly storage, so for now, I've gotten them all beat!
As far as saying NO, I do that every day, but as soon as DH is home- it all goes haywire- of course kids always go to the "YES" parent. They're not stupid, I've talked until I'm blue in the face with DH about this and he just shrugs it off. He says that he works hard so we can have the things that we want, and if it's food, then he and the boys will have it.
We've been at loggerheads over this issue for 18 years.