Any advice on keeping a teen out of the fridge?

I have a 12 year old that we have had continuous issues with sneaking food. Primarily junk food. This has been an on going problem since the age of 6 when we took her into our home. We have tried what seems like everything....therapy, nutritional counseling, positive reinforcement (sticker charts), consequences such as grounding, losing privileges, making her pay for the food she sneaks, letting her get involved with the grocery shopping so she has some "healthy" options for her to choose from if she is hungry, removing items that seem to be "trigger foods", etc., etc., etc. She only does this behavior in the early morning hours (4-5am) before she has had her ADHD medication. It has come to the point where we have had to put a lock on the pantry door, but we don't have a way to keep her out of the fridge/freezer. There is a much larger underlying problem here that needs to be addressed, which is why we have been doing therapy with her. I'm fearful that if we don't get this under control now, this behavior could manifest itself into something much bigger as she gets older. Any ideas on how to "lock" the fridge without using a "padlock system". I understand this isn't dealing with the root of the problem, but if we remove the temptation while we are working on the underlying problem, I am hopeful it will make our home a happier place.