Kelly, 26, who has recently dropped 50lbs, came in joint number one place with Hudson, 29, who has gone from a size 16 to size 6.
This year's top slimmers were named as having the best bodies by Fitness magazine.
Some of the other winners were former Housewife of New York star Bethenny Frankel, 40, who was named the Best Body After Baby and Kate Middleton, who won Best Bride To Be for working out at the gym an hour a day.
Single mum of eight, Kate Gosselin was crowned Best Mum Abs, while Hottest Morning Show Host was awarded jointly to 33-year-old Elisabeth Hasselbeck and Kelly Ripa, 40.
Mad Men star Christina Hendricks won Best Curves and Audrina Patridge was named the Best Reality Starlet.
Reese Witherspoon and boyfriend Jim Toth were crowned Cutest Workout Pair.