Jessica Simpson's smoothie diet

Los Angeles - Jessica Simpson kicked off her post-pregnancy weight-loss campaign with a 15-day smoothie diet.

The singer and actress - who welcomed daughter Maxwell Drew in May - had over 27kg to lose. So, to give her body the boost it needed, the singer followed a strict plan of consuming just healthy and nutritious smoothies for 15 days before slowly introducing snacks and meals.

She then spent five days having three smoothies a day with two healthy snacks, five days of two smoothies a day plus two healthy snacks and one meal and then five days of one smoothie a day with 2 snacks and 2 meals.

The plan - which was crafted by Jessica's former private chef and started in July - is part of Weight Watchers and follows its famed point system.

$4m deal signed

Jessica is the new spokesperson for the company.

According to TMZ, items on the menu included foods like egg white omelettes, chicken satay, whipped chick peas, soba noodles and shrimp skewers.

Jessica - who is now back to her pre-pregnancy weight - signed a $4m deal with Weight Watchers to become their spokesperson and follow their weight loss plan religiously.

Their plan involves giving each item of food, snacks and meals points and the dieter is not allowed to go over their daily allowance of points.