What do I do about an overweight hen?

[The Chickens' Maid]

We have a hen who is overweight. I know that this is bad for a bird, but I don't know how to deal with it. We don't give them a huge amount of treats; they eat layer pellets and any bugs they find outside mostly. She is is good health; we just wormed them and she had worms. She eats normally (I think); she drinks normally. She has a habit of drinking too much at one time and throwing it up, then eating it again. She's a bit of a pig. She's also the head hen; she's very sloppy when she eats, she likes to spread her food around and then eat it. She has a large crop, but she has had that for three or four years now. We got her as a young hen, and she has always had it. It has never caused her any problems. She has bumblefoot, too. Does anyone have any ideas?
Here's a picture of her:

 

[spook]

Could it be the breed she is? Also, she looks more fluffy then fat!
You really cannot put them on a diet if she is laying eggs, getting exercise- scratching and stuff, fresh water, it should be enough. How about some fruit and veggie scraps for a filler/satisfier....(chuckle as I look in the mirror...

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[The Chickens' Maid]

She's never really been a big egg-layer. In the past year, I think she has really slowed down. She is acting normally. I'm not sure what breed she is, although she is very fluffy; we got her and her late friend from a backyard outfit. They were already grown, and the chickens there were free range, so I think it's more likely that they were mutts. She has gained some weight in the past year, though. It's easier to see around her face, and she has a lot of "padding" under her feathers. Maybe it's just because we are heading into winter here; Connecticut winters are nasty.
I'm just hoping it's not some sort of internal problem. She's always been a large hen, though, just not this large.