A woman contemplating which bowl of Cheetos to start eating.

If you find yourself in a moment of weakness and craving some Cheetos, you should absolutely opt for the puffs. Even though you'll likely eat a larger volume, you'll end up downing fewer calories.

From the book How Not to Diet:

Researchers compared Crunchy Cheetos to Cheetos Puffs. Though both have the same number of calories per pound, the Puffs have fewer calories per volume because they’ve been puffed up with air. Study subjects were offered a big bowl of each, and, although they consumed nearly 75 percent greater volume of the Puffs, they still ended up taking in about 20 percent fewer calories, presumably because the Puffs had so many fewer calories per cup due to the added air.

Greger, Michael. How Not to Diet: The Groundbreaking Science of Healthy, Permanent Weight Loss (pp. 194-195).