The 3 Bs stand for “Boring But Big”
The “Big” part of that refers to how the program is intended to put on bodyweight. You can check out Jim’s blog as well to check out a recent interpretation of BBB titled “BBB Beefcake” that further reinforces that idea, and this from the original article
“There are a number of ways to do assistance work: Boring But Big (my version of a hypertrophy program”
One of my favorite ways to evaluate if I’m getting too fat is if my chinning performance diminishes. If bodyweight goes up but chinning stays the same or gets better, it’s probably muscle. If it goes down, it’s probably fat. Although I also just use a mirror too.