11, Potato Chips Cause More Weight Gain Than Any Other Food. A Harvard University study of more than 120,000 people found that potato chips were to blame for the gain of an average of 1.69 pounds per person over four years. Other fatteners: potatoes (1.28 pounds), sugar-sweetened beverages (1.00 pounds), and unprocessed red meats (0.95 pounds). So potato chips lovers, still craving for this snack?