Credit: Charley Gallay/Getty

Sure, she's super slim and has a model-worthy 5-foot-10 figure, but Whitney Port can still find room for improvement.

The fashion designer, 25, wrote on her blog last week about doing a three-day juice cleanse with sister Paige.

"I have been putting a lot of unhealthy things in my body recently, i.e. overeating peanut brittle, chips and dip, wine, etc., and have been feeling tired and sluggish all the time," wrote the former City star. "To us it is not about losing weight or trying the newest fad, but about being healthy and detoxifying our bodies."

Her cleanse of choice: L.A.-based Pressed Juicery, the same spot where Nicole Richie goes to pick up healthy sips.

"We decided that we wanted to try Pressed's most basic Juice Cleanse -- 6 juices a day for 3 days!" wrote Port. "I know some of you may think this is crazy, but we are going to try it and see how it goes!"

The True Whit author told last fall that she isn't big on dieting. "I try to just eat healthy and take care of myself," she said. "I don't make my diet the main focus."