Jessica Simpson's butt trainer

Jessica Simpson hired a personal trainer for new film 'Dukes of Hazzard' - to make her butt look bigger.

The sexy star was determined to have a curvy backside to play hotpant-wearing Daisy Duke in the movie version of the cult TV show.

So she employed trainer Mike Alexander - an old high school friend - to draw up an exercise and eating regime that would beef up her bottom.

Mike revealed: "Jessica wanted more of a bump for her rear end instead of a flat butt."

To achieve her perky buttocks, Jessica spent every day doing lunges and squats, while holding 7½ lbs weights.

Mike also put her through a cardio-vascular work-out, and told her to avoid bread-based foods.

Instead, he encouraged her to eat grilled chicken, seared fish and asparagus.

Mike said: "I ate every meal with her so I could tell her what to order."

Jessica, who is married to singer-turned-actor Nick Lachey, co-stars in the 'Dukes of Hazzard' movie with 'Jackass' star Johnny Knoxville and 'American Pie' actor Seann William Scott.