Nature Neuroscience is a top notch science journal and this month they have a feature: "Feeding Regulation and Obesity". This 'focus' includes several comprehensive (and pretty hard-core science) reviews on the current understanding of the neurobiology of obesity: covering the leptin system, melanocortin system, and endocannabinoid control of food intake/energy balance.
I believe all of the articles are freely accessible to the public until July, and the website is: