My horse is not fat, but he's bigger than when I got him and I would like to trim him down a little. He was pastured part of the time and put up part of the time, now he's on pasture 24/7 (I 'm thinking that has something to do with it:) I'm thinking about putting him up at night, no hay or grain. Would this help him get back to the size I want him? Also we have another horse who we're going to be putting up, and he is overweight. How long does it usually take to get them slimmed down?