Curling,
Sorry if we seem a bit rough on you. It's just we've been in your wife's shoes and don't want to see her go down the same wrong roads we did. Needless to say, we get a bit fired up on this subject.
Enough food + enough water (can't stress the water part enough) = 1 (and sometimes 2!
poops a day for me. I used to be one of those once a week folks too - YOUCH!
Without any muscle, she's not going to HAVE a metabolism. All the training or drugs in the world won't build muscle without a proper diet. Personally, I wouldn't touch T3 with a 10 foot pole. Sure, a lot of bodybuilders use it, and they know what they're doing with it, but I don't, and wouldn't want to permanently wreck my thyroid, which IS possible with T3. If I were a professional, and my career depended on it, then I might reconsider AFTER making sure my training and diet were completely on the mark.
Get her to focus on building STRENGTH. I recommend she keep a training log. That really motivated me. I liked the challenge of lifting more and more weight. That also encouraged me to make positive changes in my diet. Once I started eating a halfway decent diet (as opposed to next to nothing) the improvements seemed to happen like magic, and really stoked my metabolism. Women are completely in awe of how much I eat, and so am I
.
One more thing... she doesn't need to worry about getting "big" from lifting heavy weight (assumming she's not using steroids). That is unless she's genetically gifted, in which case she can either decide to become a bodybuilder or tone the weights back a bit. In the meantime though, she needs to build muscle in order to raise her metabolism. This is what will help her reduce bodyfat. Yes, her scale weight WILL go up, but her bodyfat should come down, and she'll be harder and tighter, since muscle weighs more than fat and is denser than fat.
I highly recommend that she read OXYGEN magazine and the book Bodyfitness for Women:
http://www.amazon.com/exec/obidos/ASIN/1552100146/qid=988404720/103-2203387-3411838