I've busted my arse trying to make tofu work on my diet - it's the cheapest source of protein I can get my hands on. Nope, nothing. Always ended up retaining water somehow (may be related to estrogens) and feeling a bit bloated and too full to run in the mornings (may be related to protease inhibitors blocking absorption of protein and leaving it for GI bacteria to chomp on).

Then again, when I say "source of protein" that means that I would be eating it for every single one of my keto meals. Which is probably far more than normal. In other words, an occasional block of tofu may not hurt.