Flours vary widely in glycemic index, from very low (around 20 or below for almond and coconut flour) to high (above 70 for refined wheat and cassava flour), with most whole-grain and legume flours landing somewhere in between. The catch is that “the GI of a flour” is a slippery concept. A flour’s glycemic impact shifts depending on how finely it is ground, what you bake with it, and whether you add fat, protein, or fiber along the way. Still, knowing the approximate GI range of each flour gives you a useful starting point for choosing ingredients, especially if you are managing blood sugar.
GI Ranges for Common Flours at a Glance
The numbers below are approximate ranges drawn from studies testing flours in baked goods or standard food products. Because different labs use different reference foods and test protocols, you will see variation from study to study. Treat these as relative rankings rather than fixed values.
- Almond flour: Very low, roughly 0–20. Extremely low in carbohydrate and high in fat and fiber, so it barely registers on glucose tests.
- Coconut flour: Very low, roughly 10–25. High fiber, low starch content.
- Sorghum flour (whole): Low to moderate, roughly 32–56 depending on particle size.
- Chickpea flour: Low to moderate, roughly 30–45 when used as the primary flour.
- Lentil flour: Low to moderate, roughly 30–45.
- Barley flour (hull-less, waxy): Low to moderate, roughly 35–50.
- Brown rice flour: Low to moderate, roughly 37–62 depending on the product.
- Oat flour: Moderate, roughly 45–65, heavily influenced by β-glucan content and processing.
- Whole wheat flour: Moderate to high, roughly 65–85 in typical bread products.
- Refined white wheat flour: High, roughly 70–95 in bread.
- Corn flour: Moderate to high, roughly 50–75.
- Cassava flour: High, roughly 91–94 in bread.
- Rice flour (white, refined): High, roughly 70–95 depending on amylose content and variety.
These ranges overlap because the same flour can produce dramatically different GI values in different recipes. A brown rice muffin tested at a GI of about 37 in one study is not the same product as a white rice noodle with a GI above 80. The flour matters, but so does everything that happens to it in the kitchen.
Wheat Flour Is Not as Simple as “White Bad, Whole Good”
One of the most persistent beliefs in nutrition is that swapping white flour for whole wheat flour will meaningfully lower the glycemic impact of your bread. The reality is more disappointing than most people expect. In lab tests comparing breads made from refined versus whole wheat flour, the estimated GI of refined flour bread came in around 93, while whole wheat bread ranged from about 83 to 85.1Cereal Chemistry. Reduced Gelatinization, Hydrolysis, and Digestibility in Whole Wheat Bread in Comparison to White Bread That is a real difference on paper, but both numbers still sit firmly in high-GI territory. Other research has been even less encouraging, finding that whole wheat bread produces a glycemic response similar to that of white bread.2PubMed Central. Microstructure of Whole Wheat versus White Flour and Wheat-Chickpea Flour Blends and Dough: Impact on the Glycemic Response of Pan Bread
Whole wheat flour does have higher mineral, protein, and fiber content than refined flour, so it is the better nutritional choice overall. But if your primary goal is lowering the glycemic impact of what you bake, switching from white to whole wheat flour alone will not get you far. You need to either blend in a lower-GI flour or change how you prepare the dough.
Legume Flours Pack the Biggest Glycemic Punch
Chickpea flour and lentil flour stand out as two of the most effective flour swaps for cutting glycemic response. In one study, replacing a portion of wheat flour with chickpea flour in pasta dropped the GI from about 73 to about 58.3Food Chemistry. Chickpea flour ingredient slows glycemic response to pasta in healthy volunteers In bread, adding chickpea flour at 35% of the total blend significantly reduced the blood glucose area under the curve compared to standard wheat or whole wheat bread.4PubMed Central. Organoleptic and glycemic properties of chickpea-wheat composite breads
Why legume flours work so well comes down to their composition. They are higher in protein and fiber than cereal flours, and their starch granules are encased in intact cell walls that resist digestive enzymes. This cellular structure slows glucose release even after baking. In fact, bread enriched with 60% cellular chickpea flour triggered significantly elevated release of the satiety hormones GLP-1 and PYY in healthy volunteers, compared to plain white bread.5PubMed Central. Enhanced secretion of satiety-promoting gut hormones in healthy humans after consumption of white bread enriched with cellular chickpea flour: A randomized crossover study So you are not just getting a lower blood sugar spike; you are also getting a food that keeps you feeling full longer.
The practical limit is taste and texture. Most bakers find that chickpea or lentil flour works well up to about 25–35% of the total blend before the flavor becomes too dominant or the texture turns dense. At those proportions, though, the glycemic benefit is real and the bread remains palatable.
Nut Flours and Their Near-Zero Glycemic Impact
Almond flour and coconut flour sit at the bottom of the GI scale because they contain very little starch. Almonds are high in fiber, unsaturated fat, magnesium, and vitamin E but low in carbohydrates, which makes almond flour a particularly attractive swap for people managing diabetes.6IOP Conference Series: Earth and Environmental Science. Almond flour and its potential in diabetes management: A short review The fat and protein in almond flour slow gastric emptying, which further blunts any glucose rise from whatever starch is present in the recipe.
The downside is that nut flours behave nothing like wheat flour in baking. They have no gluten, so they produce no elastic crumb. Products made entirely from almond flour tend to be dense, crumbly, and moist rather than airy. Coconut flour absorbs a tremendous amount of liquid, so recipes typically call for extra eggs or other binders. For these reasons, nut flours usually work best as partial substitutes or in recipes specifically designed around them, like pancakes, muffins, or flatbreads.
Sorghum, Brown Rice, and Barley
Among grain flours that are not wheat, sorghum stands out as a surprisingly low-GI option. Muffins made with sorghum flour at an intermediate grind size had a GI of about 32 in one controlled study, with brown rice flour coming in around 37 in the same test. The overall range for the grain flours tested (sorghum, corn, brown rice, whole wheat, and refined wheat) spanned from 32 to 56.7PubMed Central. Effect of Flour Particle Size on the Glycemic Index of Muffins Made from Whole Sorghum, Whole Corn, Brown Rice, Whole Wheat, or Refined Wheat Flours Those numbers came with large standard deviations, which is typical of GI testing in small groups. But the relative ranking is consistent with what other studies report: sorghum and brown rice tend to produce lower glucose responses than corn or wheat.
Barley flour, especially from hull-less waxy varieties, is another lower-GI grain option. Breads made with waxy hull-less barley flour showed lower glycemic index values and lower equilibrium starch hydrolysis compared to those made with regular barley.8PubMed. Effects of the addition of waxy and normal hull-less barley flours on the farinograph and pasting properties of composite flours and on the nutritional value, textural qualities, and in vitro digestibility of resultant breads The trade-off is texture: barley-heavy breads are denser, harder, and chewier than standard wheat bread.
Cassava and Other Root Flours
Cassava flour (sometimes sold as tapioca flour, though the two are not identical) is popular in gluten-free baking because of its neutral flavor and smooth texture. Its glycemic profile, however, is steep. Bread made with cassava flour substituted into a wheat base showed GI values ranging from 91 to 94.9PubMed. Cassava Flour Substitution Modulates Glycemic Responses and Glycemic Index of Wheat Breads in Apparent Healthy Volunteers That puts it roughly on par with refined white flour. The starch in cassava is highly digestible and contains relatively little amylose, which is the type of starch that resists rapid breakdown.
If you are using cassava flour for gluten-free purposes but want to keep blood sugar in check, blending it with a lower-GI flour like chickpea or almond can help substantially. On its own, cassava is one of the highest-GI flours available.
Why Particle Size Matters More Than You Would Expect
Grinding flour finer exposes more starch surface area to digestive enzymes, which speeds up glucose release. This effect is significant enough to shift a flour from one GI category to another. In the sorghum study mentioned earlier, the intermediate grind produced a GI of 32, while finer and coarser grinds produced different results within the same flour type.7PubMed Central. Effect of Flour Particle Size on the Glycemic Index of Muffins Made from Whole Sorghum, Whole Corn, Brown Rice, Whole Wheat, or Refined Wheat Flours
The pattern holds across different flour types. Lentil flour ground to coarser particle sizes released significantly less glucose during digestion than finer grinds, whether the flour was raw, baked, or cooked with moist heat. The coarser particles had less starch damage, fewer available carbohydrates, and higher resistant starch content.10Cereal Chemistry. Glucose release from lentil flours digested in vitro: The role of particle size This is one reason why stone-ground flours, which tend to produce coarser and less uniform particles, sometimes test lower on the glycemic scale than industrially roller-milled versions of the same grain.
For home bakers, the practical takeaway is that choosing a coarser grind when available (stone-ground whole wheat, for instance, rather than finely milled whole wheat pastry flour) can modestly lower the glycemic impact of your baked goods.
How Cooking and Cooling Change the Starch
Starch that has been cooked and then cooled undergoes a process called retrogradation, where the starch molecules re-crystallize into structures that resist digestion. This creates resistant starch, which passes through the small intestine largely undigested. Wheat products that were stored at refrigerator temperature after cooking contained about 4.5% resistant starch compared to about 2.6% in freshly prepared versions.11PubMed Central. Effect of cooking and storage temperature on resistant starch in commonly consumed Indian wheat products and its effect upon blood glucose level The same principle has been demonstrated in legume starches, where repeated cooking-and-cooling cycles boosted resistant starch content from about 32% to over 41%.12PubMed. Physicochemical properties, in vitro starch digestibility, and estimated glycemic index of resistant starch from cowpea (Vigna unguiculata) starch by autoclaving-cooling cycles
This explains why leftover rice, cold pasta salad, and reheated bread can have a lower effective GI than the same food eaten fresh. Reheating does not fully reverse the retrogradation. If you are baking bread or making flatbread and plan to eat it over several days, the portions you eat after refrigeration will have a slightly lower glycemic impact than the slice you eat warm from the oven.
Sourdough Fermentation Lowers GI
Fermenting dough with a sourdough starter, rather than using commercial yeast alone, produces organic acids that interfere with starch digestion. The effect is measurable: in one study, sourdough fermentation reduced the estimated GI of whole wheat bread by roughly 30% compared to conventionally leavened bread.13PubMed Central. Effect of Different Fermentation Condition on Estimated Glycemic Index, In Vitro Starch Digestibility, and Textural and Sensory Properties of Sourdough Bread Fermentation also increased resistant starch content while decreasing rapidly digestible starch.
The degree of benefit depends on fermentation temperature and duration. Longer, slower fermentations tend to produce more acid and more resistant starch. This is one case where the same flour, in the same recipe, yields a genuinely different glycemic product depending on how you handle the dough. For someone already using whole wheat flour and looking for additional GI reduction without switching flours, sourdough fermentation is one of the more effective options available.
The Gluten Factor
Gluten, the protein network in wheat dough, does more than just give bread its structure. It also wraps around starch granules and slows their digestion. When researchers tested bread made from gluten-free wheat flour against standard white bread, the gluten-free version produced a significantly greater blood glucose rise. In vitro digestion was faster, and less starch escaped absorption in the small intestine.14The American Journal of Clinical Nutrition. The effect of starch-protein interaction in wheat on the glycemic response and rate of in vitro digestion
This has a counterintuitive implication. Many gluten-free flours (rice flour, tapioca starch, potato starch) already tend to be high GI on their own, and the absence of gluten removes one of the few natural brakes on starch digestion. People who eat gluten-free for medical reasons like celiac disease often end up with a higher overall glycemic load unless they consciously choose lower-GI alternatives like almond flour, chickpea flour, or sorghum flour. Adding xanthan gum or other hydrocolloids can partially compensate by increasing viscosity and slowing glucose release.15Food Hydrocolloids for Health. Hydrocolloid-assisted strategies for developing low-glycemic index rice: Mechanistic roles of starch modification, bioactive fortification, and processing innovations
Oat Flour and the β-Glucan Effect
Oat flour occupies a middle position on the GI spectrum, but its glycemic behavior is unusually dependent on how it is processed. The key variable is β-glucan, a soluble fiber found in high concentrations in oats. When β-glucan remains intact and forms a viscous gel during digestion, it substantially slows glucose absorption. Products like porridge and granola, where β-glucan retains its molecular weight and viscosity, are the most effective at blunting the post-meal blood sugar peak.16Journal of Agricultural and Food Chemistry. Physicochemical Properties of β-Glucan in Differently Processed Oat Foods Influence Glycemic Response
Baking with oat flour can actually enhance this effect under the right conditions. One study found that baking increased the molecular weight and viscosity of β-glucan, which in turn improved its ability to delay starch digestion and lower the estimated GI.17PubMed. The Impact of Food Processing on the Structure and Hypoglycemic Effect of Oat β-glucan However, aggressive processing such as extrusion at high shear can break down β-glucan chains and strip away much of this benefit. Oat flour that has been gently processed retains more glycemic advantage than heavily industrialized oat products.
Rice Variety Matters as Much as the Flour Type
Rice flour illustrates how much genetic variety within a single crop can change the glycemic picture. The critical variable is amylose content. Rice varieties with high amylose produce starch that is more resistant to digestion, while low-amylose (waxy or glutinous) varieties produce starch that breaks down quickly. Different cultivars can vary from about 15% to over 30% amylose, and this directly translates to different GI values in the resulting flour and noodles.18Scientific Reports. Variability in waxy (Wx) allele, in-vitro starch digestibility, glycemic response and textural behaviour of popular Northern Himalayan rice varieties
Adding high-amylose maize starch to rice flour blends for noodle production demonstrated this clearly: as amylose and resistant starch content in the flour increased, the GI of the resulting noodles decreased.19LWT – Food Science and Technology. Effects of amylose and resistant starch on glycaemic index of rice noodles Basmati rice, which tends to be higher in amylose than most short-grain varieties, is the most commonly available “lower-GI” rice option at the consumer level. Jasmine and glutinous rice varieties sit at the opposite end.
For anyone buying rice flour for baking, this means the GI can swing by 20 points or more just based on which variety the flour was milled from. If the label does not specify the cultivar, you are mostly guessing.
Blending Flours for a Better Glycemic Profile
The most practical strategy for lowering the GI of baked goods is blending flours rather than swapping them entirely. A multigrain bread made with whole wheat flour combined with amaranth flour and plantain peel flour, sweetened with a natural sweetener instead of sugar, showed a low GI and notably lower postprandial blood glucose than a white flour control.20PubMed Central. Influence of Whole Wheat Flour Substitution and Sugar Replacement with Natural Sweetener on Nutritional Composition and Glycaemic Properties of Multigrain Bread This kind of multi-flour approach works better than any single substitution because it stacks several glycemic brakes at once: the fiber from whole grains, the protein from legume or nut flour, and the resistant starch from less digestible grain sources.
A reasonable starting formula for home baking is to use whole wheat or another whole grain flour as 50–60% of the blend, add 20–30% legume flour (chickpea or lentil), and optionally include 10–20% nut flour for richness and additional glycemic blunting. The exact ratios depend on what you are making. Pancakes and muffins tolerate high proportions of non-wheat flour better than yeast breads, which need at least some gluten-forming flour for structure unless you are willing to accept a denser loaf.
Why GI Numbers for Flours Are Inherently Fuzzy
If you have been looking at the ranges above and wishing for more precise numbers, the honest reality is that flour GI data are unusually noisy. The standard deviation in GI measurements is large even under controlled conditions. In the sorghum muffin study, the lowest recorded GI was 32 with a standard deviation of 17, meaning individual responses ranged roughly from 15 to 49 within the same small group of volunteers eating the same muffin.7PubMed Central. Effect of Flour Particle Size on the Glycemic Index of Muffins Made from Whole Sorghum, Whole Corn, Brown Rice, Whole Wheat, or Refined Wheat Flours Your personal glucose response to any flour depends on your gut microbiome, meal timing, what else you eat alongside it, and individual variation in insulin sensitivity.
What the numbers are good for is relative comparison. Chickpea flour will consistently produce a lower glycemic response than refined wheat flour, regardless of who is eating it. Almond flour will always beat cassava flour. The exact GI number matters less than the ranking, and the ranking is fairly stable across studies. Think of flour GI values the way you think of fuel economy ratings on a car: the number you see in real-world driving will differ from the lab number, but you can still trust that the car rated at 40 miles per gallon will outperform the one rated at 18.
Satiety Hormones and the Downstream Effects of Low-GI Flours
Beyond the glucose curve itself, low-GI flours trigger measurable changes in appetite-regulating hormones. When people ate low-GI food compared to standard white bread, they produced significantly more GLP-1 and PYY (both of which suppress appetite) and significantly less ghrelin (which drives hunger). These hormonal shifts correlated with higher fullness scores and lower hunger scores in both normal-weight and obese participants.21Journal of Food and Nutrition Research. Efficacy of a Novel Low-Glycemic-Index Medical Food on Satiety and Gut Hormone Responses in the Normal-Weight and Obese The obese group showed an especially strong suppression of ghrelin after the low-GI food, which translated into a tendency to eat less at the next meal.
This suggests that choosing lower-GI flours for regular baking has effects beyond blood sugar management. The difference between a muffin made with chickpea-wheat blend and one made with refined white flour is not just the glucose peak. It is also how hungry you feel two hours later and whether you reach for a second snack. For people trying to manage weight alongside blood sugar, this hormonal dimension adds practical value that a simple GI chart does not capture.
The Pasting and Gelatinization Wrinkle
One less-discussed variable is what happens to flour when you cook it into a paste or gel before baking. Pasting whole wheat flour (essentially cooking it into a thick slurry before incorporating it into a recipe) reduced its glycemic index by over 60% in one study, alongside reductions in available starch, amylose, and amylopectin content.22PubMed Central. Pasting alters glycemic index, antioxidant activities, and starch-hydrolyzing enzyme inhibitory properties of whole wheat flour The pre-cooking step changes the physical structure of the starch in ways that make it less accessible to digestive enzymes even after the final bake.
This technique is already familiar to bread bakers who use a tangzhong or yudane (a cooked flour paste added to bread dough for softness). What those bakers may not realize is that the technique also appears to lower the glycemic impact of the finished bread. The mechanism is related to the retrogradation effect discussed earlier: pre-cooked starch that cools and is then rebaked develops more resistant starch structures than starch that is only cooked once. For anyone willing to add one extra step to their baking process, this is a low-effort way to improve the glycemic profile of standard wheat flour products without changing the flour itself.