I too have run out of clothes that fit. Every pair of pants is too big. I'm wearing pajama capri's to the gym b/c my old gym pants actually slipped off my bum a few weeks ago!
I've been through my clothes twice now, deleting everything that is too big. I took it all to work and left it for the women there. Now, I work in a shelter for abused women. They often have not a stitch of clothing when they come in and believe me, they appreciate the clothes. Sometimes we have nothing for the little women, but more often, we don't have anything decent for the larger women to wear.
I feel good, they feel good. I'm glad to give it away. I'm also not having to worry about the cost of buying new quite yet. I'm a thrift store shopper and every month or so, I go out and find a few pairs of pants that fit, more than happy to give them away when they get too big.