● Food Intelligence · Legumes

Black Beans Glycemic Index and Calculate Your Own Glucose Response

Across 485 single-item black bean logs, Signos members averaged a +36.7 mg/dL glucose peak — with 58.1% of responses topping +30 mg/dL. Keep the carb load light (0–40g) and the average drops to +28.2 mg/dL; pile on 110g+ of carbs and it climbs to +46.1 mg/dL, a 63% escalation.

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Reviewed by Grace Shryack
Signos Proprietary Data·Updated May 1, 2026·10 min read

● Powered by Signos cohort dataMedium confidence · n=485
The swap calculator below draws on 19,659 matched-pair logs — a broader cohort than the page's single-item primary, used to give every ingredient swap statistical power. Welch's t-test on matched pairs, not third-party glycemic-index tables. Each swap shows its sample size and confidence tier inline.
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Build Your Own Low GI Recipe

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Signos food logs

Tap any ingredient below to swap it for a glucose-friendlier alternative. Your Signos Glucose Score, predicted curve, and nutrition update in real-time. Every swap is data-backed by real CGM response measurements.

Ingredients — Tap to Swap
Meal Context
Pre-meal sequence
Activity after meal
Time of day
47
of 100
Signos Glucose Score
High Spike Risk
75% of members fall between +29 and +41 mg/dL
Predicted Curve · 3-hr window
1401001201401601800m30m60m90m120m150m180m+35
Peak
+35
mg/dL
Time in Range
100%
3hr window
Above 140
0m
danger zone
Swaps
0
applied
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● Key Findings · Do black beans spike blood sugar?

Yes — across 485 meals where members ate black beans alone, the average glucose peak was +36.7 mg/dL, with 58.1% of responses exceeding +30 mg/dL. In our single-item cohort of 485 black bean logs, the median peak was +34 mg/dL — below rice (+44.2 mg/dL) and chips (+38.9 mg/dL) in matched cohort data. Three levers dominate the outcome: total meal carb load (the single biggest modifier, driving a 44.9% higher peak at ≥60g carbs vs. lighter builds), protein pairing (eggs trimmed the response by −9 mg/dL in 2,305 matched logs), and morning timing (black bean meals eaten before 10 am averaged 19.5% lower peaks, p<0.001). These are observational, not causal findings.

  • ▸Carb load is the dominant lever: meals with ≥60g total carbs spiked 44.9% higher than lighter builds (p<0.001, n=7,256 vs. n=7,313).
  • ▸Eggs produced the largest protein-pairing effect: paired logs averaged +27.7 mg/dL vs. +36.7 mg/dL baseline — a −9 mg/dL reduction (n=2,305).
  • ▸Morning timing cut peaks by 19.5%: black bean meals eaten before 10 am averaged a 19.5% lower response than the rest-of-day baseline (n=1,725, p<0.001).
  • ▸Light-to-very-heavy carb escalation: going from a 0–40g carb meal (+28.2 mg/dL) to a 110g+ build (+46.1 mg/dL) widens the average peak by 63.5%.
● Signos Rules

Three citable insights from this recipe's data

Rule 1
"The Rice-Stack Penalty"
+11 mg/dL peak
Adding rice to a black bean meal was linked to an +11 mg/dL increase over the no-starch baseline in 3,856 matched logs (treatment mean +41.8 mg/dL vs. baseline +31.2 mg/dL). It's the single largest pairing modifier in the builder — larger than tortilla (+9 mg/dL), chips (+9 mg/dL), or bread (+9 mg/dL). Quinoa is the lowest-impact starch add at +7 mg/dL (n=804). In the classic burrito build, rice is the variable most worth controlling.
Rule 2
"The Egg Discount"
−9 mg/dL peak
Pairing eggs with black beans dropped the average peak from +36.7 mg/dL to +27.7 mg/dL — a 9-point reduction across 2,305 matched logs. That's the highest-impact protein modifier measured for black beans, outpacing chicken (−4 mg/dL, n=5,638) and ground beef (−3 mg/dL, n=2,057) by a wide margin. The effect likely reflects egg protein's role in blunting gastric emptying. A breakfast black-bean-and-egg bowl is a substantially different glucose outcome than a dinner burrito.
Rule 3
"The Morning Edge"
−19.5% peak
Black bean meals logged before 10 am produced peaks 19.5% lower than the rest-of-day baseline — a CI of [−7.74, −6.00] mg/dL across 1,725 morning logs (p<0.001). Breakfast beans averaged +29.1 mg/dL vs. dinner's +36.0 mg/dL. The pattern is consistent with morning insulin sensitivity advantages seen across the broader cohort. Timing your highest-carb bean meal earlier in the day is a low-friction lever.
● Curious about your own?

Curious how your body responds to black beans specifically?

Across 485 single-item black bean logs, the average glucose peak was +36.7 mg/dL — but the IQR spans 28 mg/dL (p25: +21, p75: +49). Your personal response could land anywhere from a modest rise to a significant spike. Carb load at the meal, protein pairing, and time of day all shift the outcome measurably. A CGM makes that variability visible in real time.

Learn how Signos works
Why this meal spikes

This meal stacks 3 independent spike drivers — together they account for +34 mg/dL.

Driver 1
Total meal carb load (≥60g threshold)
+15 mg/dL
When total meal carbs hit ≥60g, peaks jumped 44.9% above the low-carb baseline (n=7,256, p<0.001). Black beans in a bowl with rice and chips easily clears that threshold — the beans themselves are a medium-GI food sitting inside a high-carb context.
Driver 2
Digestible starch (~45g avg carbs per single-item meal)
+12 mg/dL
Single-item black bean logs averaged ~45g carbs. The Light carb bucket (0–40g) averages +28.2 mg/dL; crossing into Medium (40–70g) brings that to +34.8 mg/dL — a 23% escalation driven by starch load before any additional carb sources are added.
Driver 3
High sugar co-loading (≥20g sugars in meal)
+10 mg/dL
Meals with ≥20g sugar alongside black beans showed peaks 28.6% higher than the low-sugar baseline (n=1,650, p<0.001). Fast-digesting sugars accelerate the glucose curve before bean fiber can moderate absorption — a relevant risk in Tex-Mex contexts with sweetened drinks or salsas alongside.
● Which bucket are you in?

Some members spike +28.2 mg/dL. Others spike +46.1. The only way to know how you'll spike is to measure with a Signos CGM.

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● What surprised us
What surprised us about black beans is how much the surrounding build matters — and how little the bean form itself does. Refried black beans averaged just +31.6 mg/dL in matched logs — essentially the same as whole beans at +34.1 mg/dL. But add rice to the same bowl and the average climbs to +41.8 mg/dL. The form is a rounding error; the carb stack is the whole story.
— Signos Data Science Team

Why this happens, physiologically

Black beans are a low-GI legume (GI 30) whose glucose response is shaped primarily by total meal carbohydrate context. Across 485 single-item logs, the average peak was +36.7 mg/dL — but that number shifts sharply with build. Light carb meals (0–40g) averaged just +28.2 mg/dL, while very heavy meals (110g+) hit +46.1 mg/dL — a 63.5% escalation driven by what surrounds the beans, not the beans themselves. Morning timing adds a secondary buffer: black bean meals logged before 10 am ran 19.5% lower than the rest-of-day baseline (p<0.001, n=1,725), an observational pattern consistent with improved morning insulin sensitivity.

● Three levers explain the cohort range

Total carb load, meal timing, and protein pairings together drive black beans' wide glucose range from +28 to +46 mg/dL

  1. Mechanism 1
    +45%
    High-carb meal load
    Meals with ≥60g total carbs spiked 44.9% above the low-carb baseline (n=7,256, p<0.001). Rice, tortilla, and chips each add +9–11 mg/dL on top of the bean base in matched logs — carb stacking is the primary amplifier.
  2. Mechanism 2
    −19.5%
    Morning timing benefit
    Meals logged before 10 am averaged 19.5% lower peaks than daytime meals (n=1,725, p<0.001). Breakfast black beans tracked at +29.1 mg/dL vs. dinner's +36.0 mg/dL — a consistent morning advantage across the cohort.
  3. Mechanism 3
    −9 mg/dL
    Egg protein pairing
    Adding eggs dropped the average peak from +36.7 to +27.7 mg/dL (n=2,305). This is the strongest protein modifier measured — well above chicken (−4 mg/dL) and ground beef (−3 mg/dL). Egg protein delays gastric emptying and blunts carbohydrate absorption rate.
● Fit Check
Black beans are a genuinely low-GI food — the glucose outcome depends almost entirely on the carb load and protein you build the meal around.
✓ This is for you if
  • ▸You eat black beans at breakfast with eggs. That pairing tracked at +27.7 mg/dL — the lowest protein-paired peak in the dataset (n=2,305), 24% below the single-item mean.
  • ▸You keep total meal carbs under 40g. The Light carb bucket averaged +28.2 mg/dL — 63.5% lower than the 110g+ carb bucket at +46.1 mg/dL.
  • ▸You swap rice for quinoa or skip the grain entirely. Rice adds +11 mg/dL vs. no starch pairing (n=3,856); quinoa adds only +7 mg/dL (n=804).
  • ▸You eat black beans before 10 am. Morning timing was linked to a 19.5% lower peak across 1,725 logs (p<0.001) — the biggest free lever in the dataset.
✗ Not for you if
  • ▸You build a burrito with rice, tortilla, and chips. Each starch layer adds +9–11 mg/dL; a full high-carb build can push average peaks to +46.1 mg/dL (110g+ carb bucket).
  • ▸You rely on guacamole or cheese to offset a high-carb build. Guacamole cuts only −4 mg/dL (n=3,970) and cheese only −2 mg/dL (n=6,020) — not enough to counteract a full rice-and-tortilla stack.
  • ▸You regularly eat black beans at dinner. Dinner logs averaged +36.0 mg/dL — 24% higher than breakfast logs (+29.1 mg/dL) in matched cohort data.
  • ▸Your meal includes high sugar content (≥20g). That modifier drove peaks 28.6% higher than the low-sugar baseline in 1,650 matched logs (p<0.001).
● How it fits your day

Calorie band and pairings (member-measured)

Per serving
393–1,137 kcal
Ranges from a light black bean build (~393 kcal avg in the 0–40g carb bucket) to a very heavy build with rice, chips, and toppings (~1,137 kcal avg in the 110g+ carb bucket).
● Pair before
  • ▸Choose a Light carb build (0–40g total carbs): peak averages +28.2 mg/dL vs. +46.1 mg/dL in the 110g+ bucket — a 63.5% reduction.
  • ▸Eat black beans at breakfast with eggs: that combination tracked at +27.7 mg/dL in 2,305 matched logs — the lowest-peak build in the dataset.
● Pair after
  • ▸A 10-min walk within 30 min helps clear circulating glucose — relevant given 58.1% of solo black bean logs exceeded +30 mg/dL.
  • ▸Skip the rice add: rice pairing averaged +41.8 mg/dL vs. +31.2 mg/dL for no-starch baseline — a +11 mg/dL difference in 3,856 matched logs.
● Avoid pairing
  • ▸Avoid the 110g+ carb build (rice + tortilla + chips): average peak jumps to +46.1 mg/dL vs. +28.2 mg/dL for a light build — a 63.5% escalation.
  • ▸Avoid high-sugar meal co-loading (≥20g sugars): that modifier added 28.6% above the low-sugar baseline in 1,650 matched logs (p<0.001).
● Quick definitions (click to expand)
mg/dL — milligrams per deciliter. The unit blood glucose is measured in. A rise of "+30 mg/dL above baseline" means blood sugar went up 30 units after the meal.
Glycemic Index (GI) — a 0–100 score for how fast a food raises blood sugar in lab tests. Under 55 = low, 56–69 = medium, 70+ = high.
Glycemic Load (GL) — GI adjusted for portion size. Under 10 = low, 10–19 = medium, 20+ = high.
CGM — Continuous Glucose Monitor. A wearable sensor that tracks blood glucose every few minutes. Signos members wear CGMs while eating meals they log.
● Related Foods: Black beans sit near the low end of the carb-food spike ladder — here's how they compare to adjacent foods and what to pair them with.

Frequently Asked Questions

Methodology

This page draws on two cohort cuts of black beans data collected from Signos CGM members between March 2025 and April 2026. The single-item cohort — meals where black beans were logged alone, without other foods — covers 485 logged meals from 366 unique members, and is the primary source for headline stats (mean peak +36.7 mg/dL, median +34.0 mg/dL). The broader cohort, which includes all meals containing black beans in any context, covers 19,659 logged meals from 6,595 unique members (mean peak +34.3 mg/dL, median +31.0 mg/dL) and powers the modifier and recipe-builder analysis. All cohorts are filtered to meals with a measured glucose rise between 0 and 100 mg/dL (ppgr_case='regular'). Effect sizes across modifier slots were estimated using Welch's t-test on matched pairs; all modifier effects cited carry p<0.05 or better. Because glucose response distributions are right-skewed, the reported mean is typically a few mg/dL above the median. Black bean meals were identified via regex matching on logged food names. A minimum of 30 matched meals is required for any pairing to appear in the recipe builder.

Limitations

  • The single-item cohort (n=485) is medium-confidence — headline stats are directionally reliable but carry wider uncertainty than larger sub-cohorts; the broader cohort (n=19,659) powers all pairing and modifier analysis.
  • Self-reported portion sizes introduce measurement noise; members logging 'black beans' may vary substantially in actual quantity, which affects carb-load estimates.
  • Cohort skews health-motivated; members using CGMs tend to be more metabolically aware than the general population, so average peaks may be lower than a representative sample would show.
  • Black bean burger (n=304) and black bean soup (n=432) form sub-cohorts are medium-confidence; directional effects are plausible but absolute delta estimates carry wider uncertainty.
  • Tofu protein pairing (n=344) is medium-confidence; the −1 mg/dL delta is directional only and should not be cited as a meaningful reduction.
  • All findings are observational. Welch's t-test identifies statistically significant associations between modifiers and glucose outcomes, but does not establish causality.
● Get your own data

See your own black bean response

Across 485 single-item black bean logs, the average glucose peak hit +36.7 mg/dL — but 47% of those responses classified as high-spike while 23.3% stayed low. That spread isn't random: meal carb load alone drove a 63.5% escalation in peaks, from +28.2 mg/dL in light-carb builds to +46.1 mg/dL in very-heavy ones. A CGM tells you exactly where you fall — and which build (eggs instead of no protein, quinoa instead of rice) actually moves the needle for your biology.

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