Star Weight-Loss Winners & Losers

Which celebs are triumphing over the battle of the bulge?

Related: Five Celebrity Diet Tips for 2013 Resolutions

From Christina Aguilera to Kirstie Alley, ET breaks down the stars who are staying trim during the holidays.

Also Thursday, Julianne Hough reveals physical and mental abuse as a child. Plus, an exclusive first look at Jennifer Lopez's sexy spread in Bazaar magazine.