He jokes that he has a six-pack of rolls instead of muscles.
six-pack of rolls
idiomA fat belly, as opposed to one with a six-pack. See definitions 1 and 2 of six-pack. Seldom used in the plural.
Origin
disputed originLikely by analogy with six pack of abs, the abs exchanged for rolls (“visible folds in the belly caused by obesity”).
After years of sitting at a desk, he noticed his stomach had turned into a six-pack of rolls.
Despite his youthful vanity, he eventually traded his athletic ambition for a comfortable life and a soft six-pack of rolls.