Robert Kardashian Hollywood Dancing With The Stars

Rob Kardashian has been working to lose weight as part of his Dancing With The Stars has experience (the reality star admitted to being addicted to junk food on Keeping Up With The Kardashians), and it looks like he's sticking to a regime!

Rob, 24, sported a Z.E.N. Foods lunchbox as he left rehearsal on Saturday. Z.E.N. (Zero Effort Nutrition) is a Los Angeles company that delivers "nutritionally balanced and calorie controlled, freshly cooked" meals to customers. Meals include filet mignon with fresh veggies -- fancy!

Kardashian is so committed to DWTS that he skipped sister Kim's 31st birthday over the weekend, Tweeting: "Sad I'm not with the Fam celebrating @KimKardashian's Bday but need to get this Cha Cha down for Monday! #Vote4Rob :)"

Another contestant who was looking to lose weight this season was Ricki Lake, but she might be falling off the weight-loss wagon! We spotted the former talk show host leaving practice with a very different bag full of stuff -- see what it was after the jump!