Made on
Tilda
Legumes are often praised as a "healthy carb" — but how much insulin do they actually trigger? A deep dive into the insulin index of beans, lentils, peas, and fermented soy products, with data-backed rankings and practical meal guidance.
The Insulin Index (II) measures how much insulin your pancreas secretes in the two hours after eating a specific food — relative to the same caloric portion of white bread, which is assigned a reference score of 100. Unlike the Glycemic Index (GI), which only tracks blood glucose, the II captures the full insulin demand of a food, including the insulin-stimulating effect of protein and fat.
All foods are scored relative to a 240 kcal portion of white bread consumed under identical conditions.
The II was pioneered by Dr. Susanna Holt at the University of Sydney in 1997 and has since been validated in multiple clinical settings. It is especially useful for people managing type 2 diabetes, insulin resistance, or metabolic syndrome — conditions where how much insulin a meal provokes matters just as much as how high blood sugar rises.
Legumes — a botanical family that includes beans, lentils, chickpeas, peas, and soy products — are nutritionally exceptional. Unlike refined carbohydrate foods such as bread or rice, most legumes contain a unique combination of properties that dramatically blunt the insulin response:
The table below presents insulin index values for the most commonly consumed legumes and bean-derived foods. Values are based on published research and represent mean insulin demand per 240 kcal serving, relative to white bread (II = 100). Use the category filter to navigate by food type.
| Food | Serving | II Score | Level | Visual | Notes |
|---|---|---|---|---|---|
| Fresh soybeans | 100 g cooked | 20 | Low | Lowest II in category; rich in isoflavones | |
| Miso paste | 1 tbsp (17 g) | 25 | Low | Fermented; low serving size; high sodium | |
| Tempeh | 100 g | 30 | Low | Fermented; high protein improves satiety | |
| Mung beans | 100 g cooked | 30 | Low | Popular in Asian cuisine; very high fiber | |
| Hummus | 100 g | 35 | Low | Tahini & olive oil lower II further | |
| Black beans | 100 g cooked | 38 | Low | High anthocyanin content; excellent metabolic profile | |
| Chickpeas (garbanzo) | 100 g cooked | 40 | Low | Widely studied; strong evidence for II reduction | |
| Kidney beans | 100 g cooked | 40 | Low | Must be boiled thoroughly; raw beans are toxic | |
| Pinto beans | 100 g cooked | 42 | Low | Common in Mexican cuisine; versatile | |
| Green peas | 100 g cooked | 45 | Low | Fresh or frozen preferred over canned | |
| Edamame | 100 g | 50 | Low | Immature soybeans; higher II than tempeh/miso | |
| Cannellini beans | 100 g cooked | 52 | Low | White kidney variety; common in Italian dishes | |
| Lentils (brown/green) | 100 g cooked | 55 | Low | Note: published estimates range 40–58; 55 is consensus mean | |
| Red lentils (split) | 100 g cooked | 62 | Medium | Higher II than whole lentils due to less intact cell walls | |
| Navy beans | 100 g cooked | 65 | Medium | Base bean in most commercial baked beans products | |
| Fava beans (broad beans) | 100 g cooked | 70 | Medium | Higher starch content than most beans | |
| Canned beans (plain) | 100 g drained | 72 | Medium | Rinse thoroughly; retort cooking raises starch availability | |
| Baked beans (canned, sweetened) | 100 g | 120 | High | Added sugar & tomato sauce significantly raise II |
Not all legumes are equal. Processing, added sugars, and cooking method can dramatically change the insulin demand of an otherwise healthy food. Here is a clear breakdown:
Fresh soybeans, miso paste, tempeh, mung beans, hummus, and black beans all score below 40 — making them among the most insulin-friendly carbohydrate foods available. These are ideal choices for people managing insulin resistance or following a low-insulin diet.
Chickpeas, kidney beans, pinto beans, green peas, edamame, lentils, navy beans, and fava beans fall in the low-to-medium range. They are still excellent choices and far superior to most grain-based foods, but portion size matters — especially for navy and fava beans.
"The legume family is one of the most consistently beneficial food groups for postprandial insulin management. Even the higher-scoring members of this family — whole navy beans or fava beans — produce a substantially lower insulin response than an equivalent caloric portion of pasta or potatoes."
Commercially prepared baked beans are the major exception in this food group. With an II of approximately 120 — higher than white bread — they are driven not by the beans themselves but by the sweetened tomato sauce added during processing. Molasses, brown sugar, and high-fructose corn syrup are common additions that disqualify baked beans from the "healthy legume" category despite their base ingredient.
The way you prepare legumes can meaningfully shift their insulin demand. Here are the most evidence-backed findings:
Incorporating legumes into everyday meals is one of the most practical dietary strategies for reducing average daily insulin demand. Below are three meal ideas with estimated meal-level insulin index scores:
Generally, yes — but modestly. The high-heat retort canning process partially gelatinizes starch granules, making them more accessible to digestive enzymes and raising the II by roughly 10–20 points compared to slow-simmered dry beans. However, rinsing canned beans thoroughly before eating removes some of the dissolved starchy liquid and brings the effective II closer to that of home-cooked beans. For most people, the convenience of canned beans outweighs the small difference in insulin demand.
Both are excellent choices with similar insulin index scores (chickpeas ~40, lentils ~55 for whole varieties). Lentils cook faster without soaking, making them more practical for daily use. Chickpeas have a slightly lower II and a very strong research base, including randomized trials showing reductions in fasting insulin after 12 weeks of daily consumption. For most people, variety is more important than choosing one over the other — alternating between them delivers a broader range of fiber types and phytonutrients.
Legumes are among the most consistently recommended foods for people with type 2 diabetes in guidelines from the American Diabetes Association, Diabetes UK, and the European Association for the Study of Diabetes. Their low insulin index, high fiber content, and protein density make them uniquely beneficial. That said, portion size still matters — even low-II foods can raise insulin meaningfully in large quantities. A standard serving of 80–100 g cooked beans (roughly half a cup) is a practical and well-tolerated amount for most individuals. Anyone adjusting their diet for T2D should discuss changes with their healthcare provider or dietitian.
Commercial baked beans products are prepared with significant quantities of added sugar — typically molasses, brown sugar, or high-fructose corn syrup — as well as a sweetened tomato sauce. The base navy beans themselves would score around 65 on the insulin index. The added sugars and sauce push the final product to approximately 120, making it one of the few legume-based foods that actually scores above white bread. Reading nutrition labels is essential: look for products with less than 5 g of sugar per 100 g, or make your own version at home without added sweeteners.
No — and the difference is particularly important for legumes. The GI and II of most legumes track reasonably closely because both are low, but the mechanisms differ. The GI purely reflects blood glucose rise; the II reflects total insulin secretion. For foods with significant protein content (as legumes have), the II can be disproportionately higher than the GI because protein itself is a potent insulin secretagogue. In practice, the II provides a more complete picture of metabolic impact and is generally considered more clinically relevant for managing insulin resistance.