In his American Recovery and Reinvestment Act of 2009, Obama increased the amount of value individual food-stamp users can take from the program by 13.6%, and relaxed eligibility requirements. The ARRA also provided hundreds of millions of dollars to states for administrative expenses connected with their implementation of the new benefits. Higher benefit amounts not only dramatically raised program costs, but — of course — also encouraged more American to access the program, creating a snowball effect.
So that is why food-stamp program costs have risen so dramatically and disproportionately under Obama: he has increased the benefits during a — his — prolonged economic stagnation, so that many more people want to take advantage of the much more generous benefits. Meanwhile, he has overseen rising food prices and gas prices (which contribute mightily to food transportation costs).
Worst of all, of course, is that Obama is borrowing the money to fund this scheme from our children, creating unprecedented levels of national debt.