> eat actual plastic.

Foreseeing such Crimes of the Future, David Cronenberg has already made that one into a movie.

I mean I've seen "low calorie bread" that was basically industrial bread cut with cellulose which is analogous to very fine sawdust.

Cellulose is one of the main constituant of plants and as a fiber, great for your gut:

> In human nutrition, cellulose is a non-digestible constituent of insoluble dietary fiber, acting as a hydrophilic bulking agent for feces and potentially aiding in defecation.

https://en.wikipedia.org/wiki/Cellulose

Workshop sawdust would be a bad idea though.

I'm dubious about the idea that the cellulose additive is no different than eating plants. The forms that are used in food are refined / modified, i.e. not the same thing that I eat when I eat plants. I know a few people who react very badly to this added cellulose but don't have issues eating plants.