The agency will launch a new TV and press campaign for the brand in the autumn.
Leo Burnett previously held the £2m account, but it is not known whether the agency was involved in the pitch.
Ian Priest, founding partner of VCCP, said: "Heinz is one of the world's most instantly recognisable and trusted brands and, within its target audience, Weight Watchers is not far behind."
"VCCP is tasked with not only maintaining that enviable position, but also developing and extending it into new areas."
Heinz acquired the right to use the Weight Watchers brand name from the slimming organisation in 1978, focusing on the frozen food side of the business. Its products include frozen ready-meals, pizzas and desserts.
Matthew Cullum, marketing manager for Weight Watchers from Heinz, who oversaw the pitch process, said: "We are in an ever-changing market place and one that is sure to continue to evolve.
"We were looking for an agency with interesting ideas and the skills to develop the brand still further. VCCP met the challenge."
Last November, Clemmow Hornby Inge picked up the ad account for Weight Watchers food, which is separate from the Heinz range, and includes branded products such as yoghurts and cereals, produced by manufacturers Warburtons and Yoplait Dairy Crest. JWT holds the account for Weight Watchers meetings.
Weight Watchers is the 18th biggest grocery brand in the UK, with sales of £215m-£220m in 2005. The brand is keen for to grow its share in a fast-growing but competitive low calorie food market.
In August, Suzanne Douglas Heinz's incoming chief marketing officer takes up her new position, which is expected to kick-start a review of the food giants' other creative accounts, with a view to consolidating its UK marketing efforts into one agency.
If you have an opinion on this or any other issue raised on Brand Republic, join the debate in the .