Abstract: A system for providing a user with a diet and exercise program and on-line support, comprises: a central server having a diet and exercise model, a database of personal profiles of a plurality of users, a communication unit for communicating with said plurality of users over a network, an advice calculator unit for using said diet and exercise model together with respective personal profiles to plan a personalized diet and exercise program for a given user, and a scheduler for scheduling sending of details of said program to said remote user via said communication unit, thereby to provide said user with a time-based diet and exercise program. Additionally, a query unit provides a facility for allowing the user to make on-line queries of the database. Queries may range from asking about nutritional values of given foods to requesting modifications of the diet and exercise program.