Brown rice is a better choice for blood sugar than white rice, but the difference is more modest than many people expect. With a glycemic index (GI) around 55 compared to white rice’s 73, brown rice raises blood sugar more slowly, though it still delivers a significant carbohydrate load per serving. How you prepare it, how much you eat, and what you pair it with matter just as much as choosing brown over white.
How Brown Rice Compares to White Rice
The glycemic index measures how quickly a food raises blood sugar on a scale of 0 to 100. White rice scores around 73, placing it in the high-GI category. Brown rice scores closer to 55, which lands it in the low-GI range. That gap exists because brown rice retains its bran and germ layers, which slow down digestion and the release of glucose into your bloodstream.
A large study of U.S. men and women found that replacing white rice with brown rice was associated with a lower risk of developing type 2 diabetes. The researchers calculated a mean GI of 64 for white rice and 55 for brown rice across the studies they reviewed. That roughly 10-point difference translates into a meaningfully flatter blood sugar curve after eating.
Still, brown rice is not a free pass. A cup of cooked brown rice contains about 45 grams of carbohydrates. Eating a large portion will raise your blood sugar substantially regardless of the GI score.
Why the Bran Layer Matters
The fiber, minerals, and plant compounds in brown rice’s outer layers are what give it an edge. Per 100 grams of raw brown rice, you get roughly 22 grams of fiber and 230 milligrams of magnesium. Both play distinct roles in how your body handles sugar.
Fiber slows the breakdown of starch into glucose, so sugar enters your bloodstream more gradually. It also promotes longer-lasting fullness, which can help with weight management, itself a major factor in blood sugar control. Magnesium supports the way insulin shuttles glucose into your cells. People with low magnesium levels tend to have poorer insulin sensitivity, and adequate dietary magnesium can help restore it. White rice, stripped of its bran, delivers a fraction of both nutrients.
Brown rice also contains phenolic acids and phytic acid. Phenolic compounds have been linked to blood sugar-lowering properties, partly because they may slow the enzymes that break down carbohydrates during digestion. These compounds are largely absent from polished white rice.
How Brown Rice Stacks Up Against Other Grains
If your goal is the lowest possible blood sugar impact, brown rice is good but not the best grain available. Diabetes Canada classifies these grains as low GI (55 or less):
- Barley: one of the lowest-GI grains, rich in a type of soluble fiber that strongly blunts glucose spikes
- Quinoa: low GI with a higher protein content than most grains
- Bulgur: low GI and cooks quickly
- Brown rice and wild rice: both in the low-GI category
- Buckwheat: low GI despite the name, not related to wheat
On the other end, jasmine rice, sticky rice, sushi rice, and instant rice all fall into the high-GI category (70 or above). Basmati and parboiled rice land in the medium range. So if you currently eat jasmine or short-grain white rice, switching to brown rice makes a bigger difference than if you already eat basmati.
Pairing Brown Rice to Flatten the Curve
Eating brown rice on its own still produces a noticeable blood sugar spike. What you eat alongside it changes the picture. Research published in the British Journal of Nutrition tested rice meals paired with different protein sources: fish, egg whites, chicken, and soy beancurd. Rice eaten alone produced a peak blood glucose rise of about 2.56 mmol/L at 45 minutes. Adding 25 grams of protein from soy beancurd significantly reduced the glucose response over two hours compared to rice alone.
The researchers noted that the soy beancurd meal also contained 7.6 grams of fat, which likely contributed to the slower glucose absorption. The other protein sources didn’t produce a statistically significant reduction on their own. The takeaway: combining brown rice with foods that provide both protein and some healthy fat, like tofu, eggs, nuts, or avocado, is more effective than adding lean protein alone.
The Cooling Trick: Resistant Starch
Cooking rice and then cooling it in the refrigerator changes its starch structure. As rice cools, some of the digestible starch converts into resistant starch, a form that passes through your digestive tract without being absorbed. Reheating the rice afterward doesn’t fully reverse this process, so leftover rice retains some benefit.
A clinical study in people with type 1 diabetes found that cooled rice produced a significantly lower peak blood sugar (9.9 mmol/L) compared to freshly cooked rice (11 mmol/L). Multiple heating and cooling cycles increase the resistant starch content even further. This means meal-prepping brown rice ahead of time and reheating portions throughout the week could give you a small but real advantage for blood sugar control.
One caution from that same study: the lower glucose response from cooled rice also increased the risk of blood sugar dropping too low when participants used their standard insulin dose. If you take insulin, this is worth discussing with your care team before changing how you prepare rice.
Portion Size and Practical Limits
For blood sugar management, portion control matters more than any single food swap. A common starting point is about one-third to one-half cup of cooked brown rice per meal, roughly 15 to 22 grams of carbohydrate. That leaves room on your plate for vegetables, protein, and fat, all of which help moderate the glucose response.
People who fill a plate with brown rice thinking it’s a “free” health food can end up with a blood sugar spike comparable to a smaller portion of white rice. The benefit of brown rice is real, but it works within the context of a balanced meal, not as an unlimited staple.
Arsenic in Brown Rice
Brown rice contains more inorganic arsenic than white rice because arsenic concentrates in the bran layer. International food safety bodies have set a limit of 350 parts per billion for husked (brown) rice, compared to 200 ppb for polished white rice. The FDA is working on updated action levels through its Closer to Zero initiative.
This doesn’t mean you need to avoid brown rice, but it’s worth rotating your grains rather than eating brown rice at every meal. Rinsing rice thoroughly and cooking it in extra water (then draining it, like pasta) can reduce arsenic content by 40 to 60 percent. Alternating with barley, quinoa, or bulgur gives you similar blood sugar benefits with less arsenic exposure.