After my wedding in August, my wife and I began losing weight. Got a Totally Defiant with wedding money the week after the wedding. After losing about 10 lbs, I started losing hook on the ball, and pushed it off as "taming the cover", and did not correlate the two. I'm currently down about 20 lbs, have been for a little while. Haven't had a good reaction from the Totally Defiant either. This weekend I realized that my finger tips had gotten too small for my inserts. After replacing the inserts, the Totally Defiant is right back to within a board or two of where it was when I got it, and the ball felt great.
Amazing just 20 lbs can change your Grip size so much, so beware if you plan on dumping some pounds to watch your grip and thumb fit, and get some thumb tape.