Stealing food

My son is now 25. If I bought it, he would eat it, so I just bought things I wanted him to find and eat. This is the only solution I'm afraid.

I want to gently suggest, children (no matter the age) don't steal food from their parents. The nature of parent to child doesn't involve this aspect, if it does there's something drastically wrong and this doesn't sound like the case. Food and shelter shouldn't be something they feel desperate for. After all, we have taught them their entire lives to depend on us, so it creates confusion to treat them like criminals even in small ways when we want them to feel safe around us and to feel 'at home'. All younglings look to their parents and essentially our job is to nourish them - soul and body and help them learn how to fend for themselves. My grandmother knew my father would just peel though the cabinets while she was cooking looking for snacks. So before she made dinner she'd leave a whole table with nuts and cut up veg/fruit lying about. It didn't spoil his dinner, it kept him out of her hair. I have done the same for my son when he's working and forgetting to eat. Cut up veg is apparently far more attractive and easy to manage. Try leaving things like this about with nut butter or easily edible healthy things. While a little sugar and salt is good for hydration, maybe stop having sweets in the house?

My son is now 25. If I bought it, he would eat it, so I just bought things I wanted him to find and eat. This is the only solution I'm afraid.

I want to gently suggest, children (no matter the age) don't steal food from their parents. The nature of parent to child doesn't involve this aspect, if it does there's something drastically wrong and this doesn't sound like the case. Food and shelter shouldn't be something they feel desperate for. After all, we have taught them their entire lives to depend on us, so it creates confusion to treat them like criminals even in small ways when we want them to feel safe around us and to feel 'at home'. All younglings look to their parents and essentially our job is to nourish them - soul and body and help them learn how to fend for themselves. My grandmother knew my father would just peel though the cabinets while she was cooking looking for snacks. So before she made dinner she'd leave a whole table with nuts and cut up veg/fruit lying about. It didn't spoil his dinner, it kept him out of her hair. I have done the same for my son when he's working and forgetting to eat. Cut up veg is apparently far more attractive and easy to manage. Try leaving things like this about with nut butter or easily edible healthy things. While a little sugar and salt is good for hydration, maybe stop having sweets in the house?

Great advice as usual JuniperFromGallifrey

I found the term ‘steals’ troubling too. This is your child in his own home. I was concerned that you said he ‘confessed and was v upset about it’. ‘Confessed’?! Your child is not committing a crime! Being a hungry teenager and liking sweet foods is not a crime - it’s very normal! Please don’t shame your son for this - you could cause real harm to him that might be long lasting if you make a huge deal about this. Instead try to work together. If he is very overweight then maybe - with a the right, supportive and kind approach - you can work out some more healthy eating strategies together. Putting locks on cupboards will only create tension and distress in your household - and create an association between food and guilt in your son’s mind. That’s really damaging. 
My son also loves unhealthy food, he loves sweet foods and is not a fan of vegetables. Many autistic people have issues around food - it’s not unusual. It’s important that as parents we are supportive and not judgemental. All the food in my house is there for any of us when we need or want it - I would never dream of ‘policing’ the food in our house.