How do I get the weight OFF my horse!

I have what I like to call, a fatty boomba. She seems to put on weight at the sight of new grass these days.
She's a 16.2hh 20yr old warmblood, and she doesn't get worked much because of her age, and frankly her weight.

I'm a bit worried that because of her size, too much exercise will put stress on her aged joints etc and she is very sound so I'd like to keep it that way. I'm hoping to start working her again after she loses a little bit of weight. She has a fairly fat crest at the moment which is worrying me a bit.

At the moment she doesn't get any feed, and she's out in a fairly large pasture with 2 other horses but I believe she bosses them around a bit and most likely eats their food too.

I'm thinking of trying a muzzle for her, or a diet paddock but I can't decide between the two. I don't want to go out and spend money on a muzzle if she's likely to ruin it and I'll find it a few hours later at the bottom of the paddock..
Suggestions would be LOVELY =)
I'll include a fairly recent photo of her too =)

I vote grazing muzzle.

You will never know if your horse is one of the types that they do or do not work for until you try one.

I have known very few horses who were able to destroy them quickly.

A grazing muzzle would be a good place to start. Light daily exercise is also a good idea both for her weight and her joints.

^agreed, exercise is a good thing in moderation

If you get a grazing muzzle, I've noticed that the ones that attach to a halter hold up a lot better than the ones that come as one piece

She dosnt look that bad IMO. But, another idea would be to pony her at a walk while you go on a ride with another horse. That way she's getting some exersize but you arnt putting weight on her

She's not that overwieght and as she gets older she will have problems keeping weight on. Leave her alone and retire her or ride her and don't worry about it but I see no reason to try to take weight off a horse that old.

^ I agree

I agree

What do you mean by her height?