I'd be careful dealing with any fad diet products. I was once recruited by the makers of Cortislim. The CEO seemed like an honest, smart guy but I didn't take the offer. It's a good thing because the FTC went after them. The more success you have with a diet product, the more potential liability you have. All in all it's impressive that you can get a number one rank in a competitive niche.
yea i have always look after it and i usually add some fresh content and do offsite optimization and i m on first page for many competitive keywords like weight loss drugs, hoodia, diet pills, slimming pills and many more. just follow some competitor and keep track on your site. and one thing i want to share that i never purchase any link for this site. thanks