How can I help pre-teens self regulate their food intake?

[diplodocus]

I have two DDs aged 8 and 10. They eat a good balanced diet, are a pretty much perfect weight for their height and while we don't have treats every day they maybe have cake / biscuits / sweets several times a week so they are by no means forbidden. My concern is that if they are at a party or somewhere with unlimited access to "treat" type food they seem to have no off switch at all. They will easily eat 5 pieces of cake or have thirds or fourths of pudding. If I challenge them they'll say they're still hungry, which is blatantly not the case as they have already eaten far more than they would have at home. It's not a huge problem now as they aren't in these situations very often, but I worry that as they're getting older and will soon have more autonomy / money they will constantly binge on rubbish. They seem to have no concept of eating until they are full and then stopping - I've never made them clear their plates. I obviously don't want to make a huge issue out of food but I wonder if there's anything I can do to help them self-regulate a bit more in preparation for when they're older?
Any suggestions or experiences?

polite bump..

Personally, I wouldn't worry about it too much if they eat normally at home. I binge eat at parties (and I'm normal weight for my height), as do most people I know, but unless you are at 3 parties a week, it won't cause too much of an issue in the long run. I'd just talk to them about healthy eating in general, including that there are times when you might eat more than normal. I wouldn't make a huge issue of it though, as ime that makes it much worse.

If they have a healthy diet and go a bit mad at parties it shouldn't be a problem. If you are worried it'll give them a taste for the bad stuff, again, don't worry. If it's not in your house then they are rarely going to get access to it.

They'll know what it feels like to eat good food and they'll know what it feels like to eat crap. And their skin will react worse to crap as they get older.

OK - thanks. I just got a bit worried with DD boasting how many cakes she managed to cram in in 30 mins at a school picnic! I'll just chill and hope it all comes out in the wash. I just sometimes see their friend leave puddings etc. as they are full - mine will never do this!

Mine tends to feel or even be sick if she eats too much crap. She hates being sick. I'd chill if poss (not easy with kids and food).