If your wife felt good on Atkins, have her talk to me. That diet was the first time in my life I ever felt normal - although I understand that for some, low carb feels horrid. If you're one of 'em, you'll think Atkins is a miserable waste of time but you might be surprised at how the basic setup can be tweaked to work for athletes.
Does she lift? What does she weigh now, and how tall is she?