Kristin Cavallari works out four days a week.

The 25-year-old reality TV star quickly dropped the baby weight after giving birth to her son Camden in August but it took a lot of hard work.

She said: ''I work out four days a week. I do 20 minutes of cardio followed by 30 to 40 minutes of weights. And I'll do my lunges with a bicep curl so I'm working two body parts at once.''

Kristen also credits breastfeeding with helping her to lose weight.

She told Life & Style magazine: ''Breast feeding burns 500 calories a day - I read that it's the equivalent of running six miles. But I knew I would have to do some work to get my body back. I missed fitting into jeans.''

Kristen recently admitted she only ever wears make-up when she is going on a date with fiance Jay Cutler.

She said: ''Honestly, the only time I wear make-up is when we have date night. During the day, I don't wear any make-up. But I actually enjoy it. It's nice to give my skin a break, and it's not exhausting for me to get ready in the morning.

''Luckily, Jay likes me with no make-up on. So it works out.''