[sshine]

In Danish there's both "en diæt" (what you eat, permanent) and "på diæt" (on a diet, temporary).

I didn't even think about the fact that that word didn't always have the temporary meaning of the word.

[hvidgaard]

The meaning is more fluent. The doctor can put you on a strict diet with a mealplan "lægen har sat mig på en streng diæt med kostplan og det hele", that isn't necessarily temporary.

[MindTwister]

There is also "slankekur" which more or less translates to "slimming-cure"