As a general rule, our most successful diet advertisers use the following strategy:
1) Buy our Audience Finder solution by specifying a minimum Audience Score of 70 or so. Spend between $1000-5000 to establish it as a converting offer against traffic that is known to convert reasonably well.
2) Flip it to CPA pricing. If you have strong creative and good performance from #1, we can potentially get great volume on an ongoing basis.
We have other advertisers who are successful with a different strategy and are targeting sites and networks directly, but we don't share those details. You should be getting this advice already - if not, please PM me who you are working with and your account name.