Don't beat yourself up, we all go through that. I had a day like that yesterday. Especially with sweets. I don't get a sweet tooth very often, but yesterday I ate cake, cookies, ice cream and pudding. Thankfully the ice cream and the pudding was sugar-free, but still.... I also ate a bunch of other stuff.
I think every now and then we just kind of go nuts with wanting to eat all day long. Lots of us do that. 4000 calories? That's one pound. Trivial compared to the weight you've already lost. And the important thing is that you get back on track. You can get that one pound back off again. So don't be too hard on yourself
Put it behind you and move on!