Many KFC fans left disgusted and claimed that they felt sick after watching a Channel 4 documentary, which revealed how the fast-food chain prepares its world-famous gravy.

Earlier this week, the documentary was aired on TV screens across the UK. It captured the hustle inside the KFC kitchen and showed the viewers how the fast-food chain really operates. A segment showed KFC's newest drive-thru restaurant in England's Peterlee and revealed how staff prepares its gravy pots during Christmas time.

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KFC Fans Are Not Happy

Anne Walker, who works at the KFC, revealed the secrets of KFC gravy, which is so famous that according to reports some devastated customers even rang up police when their local branch in the UK ran out of it.

Walker can be seen in the video using left-over juices from the bottom of the restaurant's chicken fryers. In the documentary, she says: "You get the crackling and then three and a half liters of cold water - two scoops of crackling. You get your juices off your chicken and then you get your magic ingredient."

The KFC worker can be seen in the video using a foil bag that contains the remaining ingredient which is required to make the gravy. After adding the mixture, Walker says, "whisk it up so it's nice and smooth and all the bits are all mixed up. Voila. Then we just pop it in the microwave".

But after watching the video many Twitter users commented saying that they had been left feeling "physically sick". The documentary aired earlier this week, but if someone wants to watch the video, they can go to Channel 4's website.