Last season there were exactly 3 pitchers with 200 IP and they all sported ERAs 3.22 or lower, so the last definition would mean essentially no innings eaters at all, just three aces.
Above the 175 IP threshold only Zac Gallen was above 3.81, and his was 4.83, so he just barely missed your criterion for eating innings and all the rest were too good to be called that and were just mid-rotation guys.
Above 150 IP there were 70 pitchers, and including Gallen I see 17 guys with ERAs above 4.20. (Keeping in mind that league average last year was 4.15.)
I think the mark of an innings eater is that his manager keeps running him out there despite not being hugely successful, so I would suggest changing the point of view to the ERA being a lower threshold and not an upper one for the role. You can pick a different lower bound than the 4.20 that I used for counting purposes above, but in any case there are only a relative handful of innings eaters if you use that number of innings as the lower bound.
I might suggest looking also at guys between 100 and 150 innings - too low to qualify for the ERA title - and who compiled an ERA above 4.50. There were 19 guys like that - pitchers who kept getting the ball and who kept scuffling. They were arguably there to soak up a percentage of the team's innings for the year.