Exactly!
Make an O with your Index and Thumb and grip the saber.
Then just do your spinning and let the saber just roll around in there.
Forget about griping the hilt with a full hand, when spinning all you need to focus on is that O spot.
My wife said doing it like that really helped.

gettin a little off topic, but, i dont exactly do it that way. i do the open hand style of spinning. i'm thinkin about wrapping those common spinning points with some leather wrap or something padded, like tennis wrap, or bat wrap. I am adverse to it cause i dont want to make any "permanent" alterations to my saber.
Remember friends, exercise is only half the battle to weight loss/maintenance. Good diet is the other half