, which specialises in diet, nutrition and fitness in the UK and Ireland, took over the licence for the Florida-based weight-loss company eDiets.com in July 2004.
EDiets is the leading online diet and fitness website with more than 1.6m paid subscribers and 13m on its newsletter list.
The website offers 14 personalised programmes including the Atkins Nutritional Approach, low-fat and cholesterol-lowering plans.
It also provides a range of services to its subscribers including the latest diet news, tips and research and a personalised profile questionnaire.
E-Dialog, which has offices in Lexington and London, has been appointed to help Tesco with tools such as custom publishing, live proofing, conversion tracking and spam reporting.
It is hoped that the partnership will enable Tesco to gain more insight into the needs of its customers.
The company also publishes a personalised online interactive magazine, along with a family of industry-leading electronic newsletters.
Simone Barratt, managing director of e-Dialog UK, said: "Tesco Diets has done an exceptional job leveraging email to improve its subscribers' experience, and is an excellent example of how companies that place a premium value on communications with customers can establish and extend momentum in their marketplace."
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