A frequently-asked question about 3 Nephi 18:4–5, 9 is, “What does ‘they were filled’ mean when the disciples and the multitude had partaken of the emblems of the sacrament? Does it mean literally, physically satisfied, spiritually fulfilled, or something else?” Although the exact meaning of the word “filled” is not given here, in 3 Nephi 20:9, during the second day of the visit and the second administration of the sacrament, the record makes this clearer:
Now, when the multitude had all eaten and drunk, behold, they were filled with the Spirit; and they did cry out with one voice, and gave glory to Jesus, whom they both saw and heard.
The Nephites were filled with the spirit and with testimony through partaking of the emblems of the sacrament. The participants cried out with one voice and gave glory to Jesus. The Savior had predicted that very effect, in 20:8:
And he said unto them: He that eateth this bread eateth of my body to his soul; and he that drinketh of this wine drinketh of my blood to his soul; and his soul shall never hunger nor thirst, but shall be filled.
The intended meaning is that they were spiritually fed. However, when a person is filled with the spirit, they may also be satisfied physically and their emotional yearnings and material concerns can be reduced. For example, during a fast, pangs of hunger may not weigh one down because there is a sense of different fullness and greater satisfaction. In John 6:35, Jesus taught that he is “the bread of life”: “And Jesus said unto them, I am the bread of life: he that cometh to me shall never hunger; and he that believeth on me shall never thirst.” Although the text refers to the spiritual nutrition, then, it can be understood and applied in reference to being fully satisfied in other ways too.
Book of Mormon Central, “Why Did Alma Bless and Thank God After Eating? (Alma 8:22),” KnoWhy 115 (June 16, 2016).