I'm a lil slow in seeing this, going back to your original post and questions looking for advice, all I can say...is if you were my husband posting this, I would be so deeply hurt by your post, I'm not sure it's something I would recover from easily, if at all.
My husband and I have both put on a few pounds since our marriage. We could both stand to lose more than just a few pounds. If you really want her to lose some weight, perhaps you need to spend some more time exploring the physical intimacies of your marriage (that can be exercise) and less time noticing how other woman are noticing you..which probably isn't happening nearly as much as you would like to think.
If that doesn't cut it for you, I know of one other way your wife could lose about 200 lbs inside of a day.