Just out of some weird thoughts, can a microbe (any single-celled organisms, accepting answers for both prokaryotes and eukaryotes) ingest too much food (e.g. via absorbing too much involuntarily because the surrounding has too much of it,or via phagocytosis) and retain part of it somehow?
Being "overweight" can be characterized by larger than average cell size/mass, presence of numerous intracellular food reserves (like glycogen?). I am guessing these (increasing cell mass and food reserves) would likely happen to some extent. But do these changes affect reproductive fitness (readiness to cell division) of the microbe? (In humans, we can safely say that being overweight is detrimental to reproductive fitness.)
For instance, What would happen when microbes are over-supplied with energy-rich and carbon-rich molecules but not the other nutrients (e.g.NPK)? And once it is switched back to a "stoichiometrically/nutritionally normal" diet, would it likely have a higher/lower reproductive fitness (compared to microbes normally-fed the whole time)?