French fries may be the real potato problem. A large study tracking more than 205,000 people for nearly 40 years found that eating three servings of fries per week was linked to a 20% higher risk of developing type 2 diabetes, while baked, boiled, or mashed potatoes showed no significant increase in risk. The research also found that swapping potatoes for whole grains lowered diabetes risk, while replacing them with white rice had the opposite effect.