There is no such thing as “the least fattening staple food”. But relatively non-fattening staple foods include potatoes, sweet potatoes, and some coarse grains, such as oats, corn and so on. Not easy to get fat staple food need to have low calorie, satiety and other characteristics. Potatoes, sweet potatoes and other calories are relatively low. Every 100 grams of potatoes contain about 81 calories, 100 grams of sweet potatoes have 86 calories. All lower than the same weight of rice and noodles and other traditional staple food. At the same time, potatoes, sweet potatoes contain more resistant starch, eaten after cooling especially strong sense of satiety, to help control the total calorie. Some coarse grains, such as oats and corn, contain relatively high amounts of fiber. An important effect of fiber is to increase the feeling of satiety and reduce what a person eats. So it can also play a role in controlling calories without gaining weight. But any food, if consumed without control, will still lead to fat. The premise of not gaining weight is to control the total calorie intake.