De or het dieetadvisering?

The correct Dutch article is:

de dieetadvisering

Rule Words ending in -ing: almost always de. See the rule

How to use dieetadvisering

the dieetadviseringde dieetadvisering
this dieetadviseringdeze dieetadvisering
that dieetadviseringdie dieetadvisering
our dieetadviseringonze dieetadvisering
your dieetadviseringjouw dieetadvisering
every dieetadviseringelke dieetadvisering
which dieetadvisering?welke dieetadvisering?
a big dieetadvisering / the big dieetadviseringeen grote dieetadvisering, de grote dieetadvisering