Remember when he was in the prequels? He was chunky even then.
He isn't unfit so more training (beyond what he does already) won't do much, it's genetic.
It's natural for a lot of dudes with Māori blood to get thicc, hell most are chunky when they're young anyway but generally not as "fat" as say Samoans.
Of course some guys don't look as chunky but that's probably more to do with the genetic mix, like the euro blood is fairly strong so it tempers the Māori.
Think he has Irish and some other mixed in but he definitely looks Māori. You look at say Manu Bennett (Crixus in Spartacus, Deathstroke in Arrow), and he doesn't seem as chunky (that might change), but he doesn't have much Māori afaik.
