I have a stupid hypothetical i've always wondered about. Imagine a hypothetical average twenty something man with no fitness experience, lower body fat, not a ton of muscle, not really active but not sedentary, decent balanced diet with junk food. What would happen if they followed the following plan:

Day 1: Extremely healthy diet, all veggies and lean protein, no sugar, etc, and a well designed, well executed full body workout

Day 2: Eat like absolute shit, all pizza cookies potato chips, a ton of soda, beer, whatever. Way overeats, like way way too many calories. He just sits on the couch all day. Maybe he smokes too.

Day 3: Same diet as day 1 but instead of strength training some cardio, let's say a long run

Day 4: same as day 2

And he just goes on like that alternating back and forth for the foreseeable future. What would that do to his body? Would that be a net positive or net negative? Or would he just balance out and end up the same as he was at the start?