That causes weight gain; often of high calorie food with relatively little nutritive value.

The act of making something fatter, particularly in reference or allusion to livestock. / The act of becoming fatter.

present participle of fatten

plural of fattening

(transitive) To cause (a person or animal) to be fat or fatter. / (intransitive, of a person or animal) To become fat or fatter.

simple past tense and past participle of fatten; fatted

Third-person singular simple present indicative form of fatten

One who fattens.

plural of fattener

(rare) Able to be fattened.