Noted New York Times writer and author, Michael Pollan, among others, suggests there is a strong link between obesity in the general population and farm subsidies.
A recent study by John C. Beghin and Helen H. Jensen, Iowa State economics professors, concludes the connection is very weak, at best. The study found that the farm value of the sweetened food items is very small (below 5%). Also, countries with different or no commodity programs experience similar increases in consumption of added sweeteners.
Their conclusion was that "the current link between the US consumption of caloric sweeteners and farm policy is tenuous, although historically the link was stronger." For the full text of the report, click on the link here: http://www.card.iastate.edu/publications/synopsis.aspx?id=1069
Another link for another publication, Effects of Agricultural Policies on Human Nutrition and Obesity, click here: http://www.card.iastate.edu/research/fnp/items/NRI_obesity_poster.pdf