I've owned a fat horse for many years. It's been a bit of a nightmare through all the moves and everything. This spring, I just bit the bullet and ordered a Greenguard grazing muzzle. It's expensive, and I did NOT want to to do it. I went all in, though, and got the breakaway halter, too. I was tired and willing to do anything not to have the long battle of spring/summer (winter we have figured out as we have a Hay Chix small hole hay net for the round bale).
The GG muzzle is the best thing I've ever done, and I seriously question my mental faculties at not doing this before.
I have tried every cheap muzzle, supplements, dry lotting, whatever. They all worked to varying degrees, but she managed to either A) get it off B) neigh all day and pace from loneliness in the dry lot and start head tossing C) supplements did nothing.
She is in the pasture most of the time, and goes into the lot with her buddy at night. This way, her buddy can get enough to eat as he is not prone to fatness. She gets some TC Lite to cover her nutritional needs (1.5 lbs max a day), and she has never looked so good. I am just floored. No stiff crest, no fatty shoulders.
This is obviously just my story, and anecdotal evidence is just that. But I am just glad I did it. I have worried little to none about her foundering, and I used to stress about it all the time. And the head tossing was just horrible.