The actress, 28, shows off her flat stomach in a bikini as well as a crop top and shorts after having a digestive system painted on to it.The former soap star posed for the campaign after slimming down from a size 18.
Jen had seen her weight balloon while she was pregnant with son Bobby. But the 5ft 6ins Calendar Girls star shed more than 4st thanks to a combination of healthy eating and exercise including running, Pilates and gym workouts.
Now she is showing off the result in a campaign for breakfast cereal Kellogg's — encouraging women to eat more wheat bran to stay healthy. Jen, who now weighs 9st, said: "I was shocked to learn that four out of five people don't eat enough fibre every day, and wheat bran is one of the best kinds for a yummy tummy."