He Knows You're Eating Cake (1981)
Alternative Titles: He Knows You Know
A mysterious young man watches as women leave their Slimming World classes and follows them home.
He spies on them through the window, and upon seeing them cheating on their diet he kills them with kitchen appliances.
Starring: Patricia Hodge and Miriam Margoles.
Sandra : "Red days, green days.. Tell you what, Julie, this diet's fucking confusing."
Most Helpful User Review:
BIFTA Winner: Best Not Cheat This Week (1982)
Directed by: Melody Maker. US. Colour.