Low quality processed food-like products consumed by the masses. Usually high carbohydrate/high fat refined foods, mixed with cheap vegetable oils and fillers.
Example 1.

Friend: Hey Jenny, do you want fries with your steak?

Jenny: No thanks, I don't eat fiat food.

Example 2.

"Brian is fat because all he eats is fiat food. He needs to lay off the carbs and eat some steak".
by The Amur Leopard June 29, 2019
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