http://health.msn.com/healthy-living/hcg-diet-dangers-is-fast-weight-loss-worth-the-risk

This article is interesting because not only does it say that its fraudulent but illegal when hcg is sold for weight loss purposes. Injections prescribed by physicians must carry a warning stating that there is no proof of effective weightloss.

http://en.wikipedia.org/wiki/Obesity

This is a good resource, it provides the basic understanding of what obesity is. It also has topics that relate to obesity with a list of topics to go through.