"The study, published online August 14, 2017 in the American Journal of Preventive Medicine, found that food purchases paid for with SNAP benefits consisted of higher spending on less healthy foods, including sugar-sweetened beverages, red meat, and convenience foods, and lower spending on healthier foods such as fruits and vegetables, compared with purchases paid for with other means."

https://www.hsph.harvard.edu/news/features/snap-program-spending-less-healthy-foods/ 

http://www.ajpmonline.org/article/S0749-3797(17)30343-4/fulltext