To dream of fast food represents situations that encourage you to care about nothing except feeling good. A quick thrill. Enjoyment that lacks substance or deep emotion. It may also reflect casual sex.
Negatively, dreaming about fast food or junk food may reflect short term enjoyment that may cost you in the long term. Preferring to feel good while intentionally neglecting or avoiding responsible behavior.
Example: A man dreamed of eating junk food. In waking life he having difficulty becoming abstinent knowing full well that it was important to complete his religious training.