Losing resolve at same time each day

I've realized that I lose my resolve to lose weight each day around 4pm. I eat like a pig, feel guilty, and start over again the next day. Before that, everything gets measured and counted, but no matter what I do, I lose focus at 4pm. I've tried planning a snack for that time and pre-measuring it, but I always end up eating that and a ton of other food. Any tips or strategies for making it through my tough hour?