There is money in sports nutrition and weight loss though you just have to come at this with a angle that targets a particular group who would be likely to buy the products....
This product has been working well for me
http://aslimlife.bodybyvi.com/ So if you join up then you have to think...OK, How to pitch it to <insert target group> and then you create a site and some content that that group would appeal to.
Also find group or interest groups where weight is a big issue...Actors and actresses is an example...So creating ads and posting it on sites that they visit would work...
Girls also want to look sexy for dating...so posting ads on a dating site would work.
More or less, anyone who knows that their body shape is the key to success is going to take a look and eventually buys.
So, who is going to make money with me by doing this?