What is a good sentence for fattening?

The Word 'fattening' is a gerund (a verbal noun); the present participle of the verb to 'fatten' that can function as a noun in a sentence. The present participle of the verb also functions as an adjective.

Examples:

This feed is effective for fattening the ducks. (noun, object of the preposition 'for')

The stray is fattening nicely at the shelter. (verb)

Their menu is full of fattening foods. (adjective)