I am Buddhist, but not a strict vegetarian. When new acquaintances discover this they are often shocked and wonder, "How can this be??!!"
I'm going to try and explain my answer and see what others think. I contend that being a vegetarian can often act as a hindrance for some Buddhists. They miss the forest for the trees.
One of my own preceding factors for learning about the Dharma was a decision to look deeply at my own consumption of meat and to explore the ethical and moral implications thereof in an honest and heartfelt way that I had never done before. I made a choice not to eat meat and became a vegetarian for five years more or less in parallel to my discovering and contemplating the Buddha Dharma, but to be clear I became a vegetarian strictly BEFORE I became a Buddhist or began practicing Buddha Dharma in earnest.
Over the ensuing years since then I have abandoned being a strict vegetarian and have continued and strengthened in my practice of the Buddha Dharma.
At first, the two seemed to coincide completely, but over time I found myself dwelling on being a vegetarian and being greatly disturbed to find other Buddhists who were not. Upon hearing that another member of the Sangha ate meat I would tend to distrust them and look at them as hypocrites at worst and misguided or lower than me in their ethical understanding of Buddha Dharma at best. I was a proselytizer for becoming a vegetarian to my buddhist/ non-buddhist friends alike and worried about what more I could do to convince others.
I grew despondent and anxious over my inability to convince others and suffered thinking about and empathizing with all the animals that were being killed on a daily/hourly/second-by-second basis merely to provide the flesh for the insatiable human demand for meat. When I looked at the scale of the problem, billions of animals dying and billions of people consuming their flesh in this carnivorous world I became hopeless that it would ever stop. I thought all of these thoughts indicated progress on the path as my heart opened up with compassion for all these animals.
But there was this nagging thought that I was actually not at all happy and was actually suffering thinking about all this in a repetitive way day after day. It occurred to me that this seemed inconsistent with what my teachers said that progress on the path - on a coarse level - is seen commensurate with an increase in happiness and a decrease in suffering.
Finally, it got bad enough that I more or less confessed all the above to my teacher and his response shocked me. He laughed with a deep and merry belly laugh and advised that I should get over being a vegetarian and the best way to do this was to eat a little meat.
He asked me how many animals I had saved today suffering at being a vegetarian and how many I would save tomorrow. He contended that my choice of being a vegetarian had not helped even one animal to escape from samsara and that I had yet to even begin to reconcile with the scale of the problem of samsara as opposed to the nearly insignificant in comparison problem of the human market for meat.
He told me I needed to let go of this attachment to being a vegetarian and congratulating myself on how ethical and moral I was compared to all those who were not and to get busy doing the actual work of becoming enlightened so that I may actually help all those animals.
When I look back I think my teacher was entirely correct. Being a vegetarian had become a hindrance for me. And since that time I think of all the people (including fellow Buddhists) who react with outrage at the idea that I am not a strict vegetarian and wonder if they are not all on a similar path that will require them to put down this hindrance in the future in order to make progress.
So there you have it... a question I've been meaning to ask for awhile and inspired by activity in this related post and some of the excellent answers and discussion within.
Can being a vegetarian actually be a hindrance for some?