What is a strong thesis statement for why people are overweight?

Obesity has become a hot-button topic in the United States.  As the waistlines of Americans have bulged over the course of the last couple of decades, so too has the media and medical coverage of it.  There are a lot of directions you could take the discussion of obesity in the United States.  The dangers of processed foods and their effects on health could be a start.  The media also often reports on the lack of opportunities for exercise for American youth.  Many people believe that, as children grow more attached to electronics and other gadgets, they exercise less.  There is also the connection that can be made between poverty and poor nutrition, which leads to obesity. If I were doing research and creating an essay, I would look at the work of Harvard professor Walter Willett.  He makes the connection between the capitalism of food production, how it targets children for poor nutrition, and what impact this has on the nutrition of said children as adults. If you would choose to use Willett's work, your thesis statement would look something like this: 

The obesity problem in the United States is a result of aggressive marketing campaigns aimed at children. These marketing campaigns are perpetrated by large food corporations and attempt to attract children to unhealthy food options.