How well does your body handle it? This is different for everyone, but my body would revolt if I ate it even once a day - it's limited to no more than once/week. Most people do quite well with limited or no grains in their diet... it's just that most people don't know how to eat without grains, because we're raised depending on them and being told they're crucial.
It also depends on what the rest of your diet looks like. If you're getting plenty of protein, fat, and produce, then having rice may not be a big deal, but if you're eating rice instead of eating those things, then that's a problem.
