Lots of scientists are interested in your questions. The link between caloric restriction and aging is a really hot research topic. Believe it or not, model organisms like yeast and nematodes (a type of worm) are the best models for asking this question. You might also check out something called the LEPTIN RECEPTOR, which has been well-studied in mice. Mutations in leptin and its receptor have been linked with human eating disorders. You can get information on these topics by running literature searches on the database called PubMed or by visiting the websites of some key journals such as Cell, Nature and Science. It is also possible that the PBS show called NOVA has run a few spots on this topic and that the National Institutes of Health (www.nih.gov) may have some links on its website.

Also check out the magazine Scientific American (www.sciam.com). Finally, the American Society for Cell Biology (ASCB) website (www.ascb.org) may be able to link you to some sites that would be able to directly help with your experiment in terms of design and available reagents plus model organisms. Of course, how you monitor and, especially, how you quantitate the effects of "overeating" are going to be the big challenge. Good luck!