Q: I’ve been advised to follow a paleo diet, with no grains, dairy, beans, or sugar. It’s ok for me to have just a little rice though, right? There’s no gluten, so it shouldn’t be as bad as wheat, right? – BK, Broomfield
A: The short answer is a simple “no”. No grains (or even pseudo-grains like quinoa) are approved on the paleo diet. The longer answer is, as always, “it depends”; that is to say, “It depends on how strictly you, as an individual, need to follow the precise plan in order to meet your goals and live your life the way you want to”.
You are right that rice does not contain gluten. Gluten, however, is just one type of lectin, and like all grains, rice contains lectins that prevent your body from digesting it well. Brown rice also contains phytin, which prevents your body from absorbing other nutrients. That being said, you are right that rice is not as bad as wheat, but it’s still not great. Rice also has a pretty weak nutrition-to-calorie ratio  when you compare it to the colorful veggies and pasture-raised meat your paleo diet recommends.
The main thing to look at it is how your body responds to rice. Even Mark Sisson has said that a little bit of rice in the right context probably won’t do any harm, so the question is “what is the right context?”.
Let’s compare grains to cigarettes. If a healthy, strong, physically active young adult who hikes Long's Peak on an annual basis decided (for whatever bizarre reason) that he wanted to start smoking one light, filtered cigarette a week, he could probably do that for the rest of his life with no ill effects at all. If, however, a 50-year-old with a decades-long, 2-pack-a-day unfiltered Lucky Strike habit and early signs of COPD decided to cut down to the same amount, it wouldn’t be the same story; even if he managed to keep to one smoke a week without building back up, he wouldn’t be able to ever fully quit the addiction and get past the “craving” stage, nor would he allow his lungs to really heal from the decades of damage he’d done to them.
Similarly, if a strong, active individual with good insulin sensitivity were to add in a serving of rice occasionally, particularly after a strenuous workout, it would likely do him no harm at all. But if someone with digestive inflammation and a blunted insulin response were to simply try to cut down from frequent consumption of gluten grains like wheat and oats to the occasional serving of rice, it wouldn’t have the same effect; even if he managed to keep the intake low, it would still prevent his gut from healing and his insulin receptors from re-sensitizing.
One of the best options is to spend a month or more following a strict diet (the Whole 30 plan from Dallas and Melissa Hartwig is one excellent choice), then try adding in foods, one at a time, to see how your body responds. This will work better than any cookie-cutter plan you might select.