In The Omnivore’s Dilemma, Pollan regretfully concedes that he’ll have to become a vegetarian as he sorts out the ethical questions surrounding meat-eating. He explains,
According to Peter Singer I can’t hope to answer that question objectively as long as I’m still eating meat. “We have a strong interest in convincing ourselves that our concern for other animals does not require us to stop eating them.” I can sort of see his point: I mean, why am I working so hard to justify a dinner menu? “No one in the habit of eating an animal can be completely without bias in judging whether the conditions in which that animal is reared cause suffering.” In other words, I’m going to have to stop eating meat before I can in good conscience decide if I can continue eating meat, much less go hunting for meat. (312)
Pollan takes Singer up on the challenge, but it’s hard to see how this makes him any less biased. He writes,
So on a September Sunday, after dining on a delicious barbecued tenderloin of pork, I became a reluctant and, I fervently hoped, temporary vegetarian. (313)
Even if Pollan is not “in the habit of eating an animal,” he clearly continues to want to eat animals, even telling us that he “fervently” hopes that he’ll be able to eat them again. So how exactly does his vegetarianism reduce his bias?

The Omnivore’s Dilemma: My Review « Say what, Michael Pollan? said
[...] Pollan gives up meat for a while, inspired by an argument of Peter Singer: “No one in the habit of eating an animal can be completely without bias in judging whether the conditions in which that animal is reared cause suffering” (312). Yet he identifies himself as “a reluctant and, I fervently hoped, temporary vegetarian” (313), so it’s not at all clear that the experiment does anything to lessen his bias. [...]