Kimberly Lyn "Kim" Lyons is an American athlete, personal trainer, nutritionist, and fitness model who has appeared several times on the covers of many health and fitness magazines and has also starred on the United States version of the competitive reality television show, The Biggest Loser. She originally replaced fellow trainer Jillian Michaels in season 3, but competed against her in season 4. She did not return for season 5, and has not made an appearance since. Subsequently, she appeared at the 2008 Miss America pageant as a panelist, and wrote a book entitled Kim Lyons: Your Body, Your Life.