Mare needs to lose some weight

I just bought a 7 1/2 year old mare, and she's the sweetest thing ever! But she is about 150 lbs overweight...she wasn't worked much previously so just having a routine training schedule should help get the weight off...but in the meantime the vet has told me NO TREATS (other than sugar-free candy if I want to give her some)...has anyone else had an overweight horse and how long did it take him/her to slim up?

Also -- is there anything (besides sugar-free candy) that I can give her as a treat once in awhile (in moderation of course!) that won't set her back on her "diet" plan?

With the cold coming on, I guess I wouldn't worry too much about a little bit of extra weight. We purposely added some pounds to our Joshua. The nutritionist came out and thought he should have some extra pounds before it got really cold. I think I'd ask the vet if you could worry more about changing that fat to muscle and not worry so much about getting the weight off as we head into the cold weather.

What about some carrots? We treat some with a large bag of peppermint flavored horse treats (but not much...I purchased the 20 lb bag in August and feed four horse and two or three dogs from the same treat bag. (Yes, the dog things those things are heavenly). We also use peppermints. But, again, we don't give treats often.

Carrots are actually very high in natural sugars :(

What all are you planning on feeding her?? Hay and feed wise??

Alfalfa cubes are good treats that won't make her fat.

Bananas (in moderation, no peels)

Wheat thins/triscuits

I wouldn't shed too many pounds off of her this winter - it's a lot harder to put them back on (especially in the winter!)

Thanks for all the feedback everyone! She is actually already starting to tone up and is looking nice, and I decided to do what everyone's said -- not worry so much about her weight so long as her health is fine and the extra lbs aren't causing any issues. I have been giving her sugar-free peppermints (in moderation), and every once in awhile someone at the barn will offer her a piece of an apple which I don't think is going to set her back too much!

It does get cold here in winter (it's been in the 20's and 30's lately and winter hasn't even really started yet!), and we have about a foot of snow on the ground already - so I think I may take the "wait until summer to shed lbs" advice and keep her warm & happy!

Hey has anyone put one of those Jolly Ball treats in their horse's stall before? How bad are those for them...are they basically pure sugar? I'm thinking she can't really have one, but I'm looking for other ideas about what I can put in her stall to avoid boredom. There's a Jolly Ball on a string in there now but I don't think she touches it...but she DOES love her peppermint-flavored mineral block!!