Study analysis · Foods · 2018
This one processing trick turns lentils from blood-sugar heroes into sugar bombs.
Boiled lentils keep your blood sugar steady, but spray-dried lentil flour spikes it like white bread.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
In simple terms
This study tested what happens to blood sugar right after people eat different kinds of lentil meals — like soup or meatloaf — and compared them to potato meals. It found that lentil meals made people's blood sugar rise less, but only for that one meal. It doesn't prove eating lentils every day will keep you healthy long-term.
What’s the bottom line?
Lentils can help keep your blood sugar steady after eating — but how you cook them matters a lot.
How strong is this study?
The study did a good job by randomly giving people different meals and measuring blood sugar carefully. But it only had 10 people in each test, and everyone knew what they were eating — so it's not perfect. That means we can trust the results for these meals, but we shouldn't assume they work the same for everyone or over time.
40 / 100
- COI disclosure+40/40
- Data availabilitydata not shared
- Code availabilitycode not shared
45 / 100
- Randomization+20/20
- Blindingnot blinded
- Control group+15/15
- Sample size (n=10)+1.0/20
- Follow-upno follow-up reported
100 / 100
54 / 100
- P-values+15/15
- Effect size+20/20
- Confidence intervalsno confidence intervals
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 557 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
This design can establish causation. Although this is a randomized controlled trial, the small sample size (n=10 per study) and lack of blinding reduce confidence in causal inference. However, randomization allows for causal interpretation of the observed differences in glycemic response between lentil and potato-based foods.
No Conflicts
No conflicts of interest identified
No conflicts of interest or funding disclosures were explicitly stated in the text; no industry affiliations or financial ties were identified among authors or institutions.
Although the study was conducted at Glycemic Index Laboratories and used materials provided by Alliance Grain Traders Inc., there is no explicit declaration of funding, author affiliations with industry, or funder involvement. Without a COI statement or funding disclosure, the absence of evidence cannot confirm independence, but no red flags for bias are present in the reported methods or results.
Key takeaways
- 01
Boiled lentils lowered blood sugar by 40% compared to potatoes (73%).
- 02
Spray-dried lentil flour spiked blood sugar like white bread (GI 66).
- 03
Freezing lentils didn't change their benefit.
- 04
People liked lentil chicken and soup almost as much as regular meals.
- 05
Yes — swapping potatoes for boiled lentils in meals can cut blood sugar spikes by nearly half, and the food still tastes good enough for everyday eating.
Surprising findings
- Spray-dried lentil flour had a GI of 66 — higher than many refined grains — despite being made from a low-GI whole food.Most assume all lentil products are healthy, but industrial drying destroys the fiber structure that slows digestion, turning it into a fast-digesting carb.
- Lentil side dish (simple lentils + seasoning) had the lowest RGR (30%) — lower than all other lentil or potato meals.Even complex lentil dishes like meatloaf spiked blood sugar more than plain boiled lentils — meaning added ingredients can undo the benefit.
Practical takeaways
Swap instant potatoes or white rice with boiled or pureed lentils in meals to cut post-meal blood sugar spikes by nearly half.
Avoid commercial lentil flours labeled as 'healthy' — check if they're spray-dried. Stick to whole or minimally processed lentils.
high confidenceMeal-prep lentil puree, freeze it in portions, and reheat for quick, low-GI meals.
Avoid adding high-GI ingredients like refined flour or sugar to lentil dishes — they can negate the benefit.
high confidenceChoose simple lentil dishes (like side dishes or soups) over complex ones like lentil meatloaf for better blood sugar control.
This study used one lentil variety (CDC Greenland) — results may vary slightly with other types, but the trend holds.
medium confidenceWhy this study matters
Lentils vs. Potatoes: The Blood Sugar Showdown
Boiled or pureed lentils reduced post-meal blood sugar spikes by 40% (RGR), while potato meals spiked it by 73% — a near-half reduction. This was statistically significant (p<0.001) in a controlled crossover trial with 10 participants per group.
Most people think potatoes are a harmless carb — but this shows swapping them for lentils can cut blood sugar spikes by nearly half, without sacrificing taste.
The Spray-Dried Trap
Spray-dried lentil flour had a glycemic index (GI) of 66 ± 6 — nearly triple the GI of boiled lentils (25 ± 3). This means industrial processing turns a low-GI superfood into a high-GI carb.
People buy 'lentil flour' thinking it's healthy — but this study proves it can spike blood sugar as much as white bread. Marketing vs. science clash.
Freezing Lentils? No Problem.
Freezing boiled lentil puree had no negative effect on its ability to lower blood sugar — frozen and fresh puree showed nearly identical glycemic responses.
You can meal-prep lentil bowls, freeze them, and still get the blood sugar benefits. No need to cook fresh every day.
Lentil Meals People Actually Like
Apricot chicken, lemony parsley soup, and chicken pot pie made with lentil puree were rated 'like slightly' to 'like moderately' — meaning most people found them palatable.
Proof that healthy food doesn’t have to taste bland. Lentils can be delicious in everyday meals — not just boring side dishes.
Want the whole report?
Detailed mode opens the full scientific breakdown — every score component, the methodology, conflicts of interest, the evidence analysis behind each claim, and the raw study data.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Lentils can help keep your blood sugar steady after eating — but how you cook them matters a lot.
Research results
Boiled lentils lowered blood sugar by 40% compared to potatoes (73%). Spray-dried lentil flour spiked blood sugar like white bread (GI 66). Freezing lentils didn't change their benefit. People liked lentil chicken and soup almost as much as regular meals.
What this means - more context
Yes — swapping potatoes for boiled lentils in meals can cut blood sugar spikes by nearly half, and the food still tastes good enough for everyday eating.
This study investigated how processing methods affect the postprandial glycemic response (PPBG) and consumer acceptability of lentil-based foods compared to potato-based controls.
Boiled or pureed lentils significantly reduce PPBG compared to potato meals (RGR 40% vs. 73%), while spray-dried lentil flour increases PPBG (GI 66 vs. 25). Freezing lentil puree preserves glycemic benefits, and consumer acceptability of lentil meals like apricot chicken and lemony soup is moderate to high.
Methods Used
Three randomized, crossover, acute human feeding trials (n=10 per study) measured glycemic response using finger-prick blood glucose sampling at 0–120 min after consuming standardized carbohydrate portions of lentil or potato foods. Glycemic index (GI) and relative glycemic response (RGR) were calculated against white bread. Consumer acceptability was assessed via hedonic scales in 92 participants.
Main Finding
Boiled and pureed lentils reduced RGR by 40% vs. 73% for potato (p<0.001); spray-dried lentil flour had significantly higher GI (66±6) than boiled lentils (25±3, p<0.05); freezing lentil puree preserved low glycemic impact; and lentil-containing meals like apricot chicken and lemony soup were rated 'like slightly' to 'like moderately' for acceptability.
Confidence Level
High — randomized crossover design with controlled carbohydrate doses, repeated measures, statistical significance reported (p<0.05), effect sizes provided, and adequate power (80% to detect 35% difference).
Study Flags
Red Flags
- •No blinding in feeding trials
- •Small sample size per trial (n=10)
- •Limited generalizability due to single lentil variety and Canadian cohort
Surprising Findings
Spray-dried lentil flour had a GI of 66 — higher than many refined grains — despite being made from a low-GI whole food.
Most assume all lentil products are healthy, but industrial drying destroys the fiber structure that slows digestion, turning it into a fast-digesting carb.
Practical Takeaways
Swap instant potatoes or white rice with boiled or pureed lentils in meals to cut post-meal blood sugar spikes by nearly half.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 557 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Human RCT
Subject
Moderate probability
on the GRADE evidence scale
This study tested what happens to blood sugar right after people eat different kinds of lentil meals — like soup or meatloaf — and compared them to potato meals. It found that lentil meals made people's blood sugar rise less, but only for that one meal. It doesn't prove eating lentils every day will keep you healthy long-term.
No conflicts of interest were detected in this study. No score impact.
Strengths
- Randomized crossover design controls for individual variability
- Well-defined and standardized food preparations
- Use of validated glycemic response metrics (iAUC, RGR, GI)
Weaknesses
- Very small sample size (n=10 per study)
- No blinding of participants or researchers
- Limited demographic diversity
Methodology
Evidence Keywords
Statistical Reporting
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Lentils can help keep your blood sugar steady after eating — but how you cook them matters a lot.
Research results
Boiled lentils lowered blood sugar by 40% compared to potatoes (73%). Spray-dried lentil flour spiked blood sugar like white bread (GI 66). Freezing lentils didn't change their benefit. People liked lentil chicken and soup almost as much as regular meals.
What this means - more context
Yes — swapping potatoes for boiled lentils in meals can cut blood sugar spikes by nearly half, and the food still tastes good enough for everyday eating.
This study investigated how processing methods affect the postprandial glycemic response (PPBG) and consumer acceptability of lentil-based foods compared to potato-based controls.
Boiled or pureed lentils significantly reduce PPBG compared to potato meals (RGR 40% vs. 73%), while spray-dried lentil flour increases PPBG (GI 66 vs. 25). Freezing lentil puree preserves glycemic benefits, and consumer acceptability of lentil meals like apricot chicken and lemony soup is moderate to high.
Methods Used
Three randomized, crossover, acute human feeding trials (n=10 per study) measured glycemic response using finger-prick blood glucose sampling at 0–120 min after consuming standardized carbohydrate portions of lentil or potato foods. Glycemic index (GI) and relative glycemic response (RGR) were calculated against white bread. Consumer acceptability was assessed via hedonic scales in 92 participants.
Main Finding
Boiled and pureed lentils reduced RGR by 40% vs. 73% for potato (p<0.001); spray-dried lentil flour had significantly higher GI (66±6) than boiled lentils (25±3, p<0.05); freezing lentil puree preserved low glycemic impact; and lentil-containing meals like apricot chicken and lemony soup were rated 'like slightly' to 'like moderately' for acceptability.
Confidence Level
High — randomized crossover design with controlled carbohydrate doses, repeated measures, statistical significance reported (p<0.05), effect sizes provided, and adequate power (80% to detect 35% difference).
Study Flags
Red Flags
- •No blinding in feeding trials
- •Small sample size per trial (n=10)
- •Limited generalizability due to single lentil variety and Canadian cohort
Surprising Findings
Spray-dried lentil flour had a GI of 66 — higher than many refined grains — despite being made from a low-GI whole food.
Most assume all lentil products are healthy, but industrial drying destroys the fiber structure that slows digestion, turning it into a fast-digesting carb.
Practical Takeaways
Swap instant potatoes or white rice with boiled or pureed lentils in meals to cut post-meal blood sugar spikes by nearly half.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 557 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Human RCT
Subject
Moderate probability
on the GRADE evidence scale
This study tested what happens to blood sugar right after people eat different kinds of lentil meals — like soup or meatloaf — and compared them to potato meals. It found that lentil meals made people's blood sugar rise less, but only for that one meal. It doesn't prove eating lentils every day will keep you healthy long-term.
No conflicts of interest were detected in this study. No score impact.
Strengths
- Randomized crossover design controls for individual variability
- Well-defined and standardized food preparations
- Use of validated glycemic response metrics (iAUC, RGR, GI)
Weaknesses
- Very small sample size (n=10 per study)
- No blinding of participants or researchers
- Limited demographic diversity
Methodology
Evidence Keywords
Statistical Reporting
Scoring
How strong is this study?
The study did a good job by randomly giving people different meals and measuring blood sugar carefully. But it only had 10 people in each test, and everyone knew what they were eating — so it's not perfect. That means we can trust the results for these meals, but we shouldn't assume they work the same for everyone or over time.
40 / 100
- COI disclosure+40/40
- Data availabilitydata not shared
- Code availabilitycode not shared
45 / 100
- Randomization+20/20
- Blindingnot blinded
- Control group+15/15
- Sample size (n=10)+1.0/20
- Follow-upno follow-up reported
100 / 100
54 / 100
- P-values+15/15
- Effect size+20/20
- Confidence intervalsno confidence intervals
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 557 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
This design can establish causation. Although this is a randomized controlled trial, the small sample size (n=10 per study) and lack of blinding reduce confidence in causal inference. However, randomization allows for causal interpretation of the observed differences in glycemic response between lentil and potato-based foods.
No Conflicts
No conflicts of interest identified
No conflicts of interest or funding disclosures were explicitly stated in the text; no industry affiliations or financial ties were identified among authors or institutions.
Although the study was conducted at Glycemic Index Laboratories and used materials provided by Alliance Grain Traders Inc., there is no explicit declaration of funding, author affiliations with industry, or funder involvement. Without a COI statement or funding disclosure, the absence of evidence cannot confirm independence, but no red flags for bias are present in the reported methods or results.
Standing
Who’s using this study?
The videos and claims on this site that lean on this study, and the researchers who wrote it.
1 video from Max German cite this study, drawing 1 claim from it.
- Very strong evidence
Randomized or controlled trials support this claim, alongside consistent supporting evidence.
Evidence