Written by Shereen, Product Management Associate · Updated 11 November 2026
Does white kidney bean extract block carbs?
It may slow the digestion of starch, the main carbohydrate in rice, noodles and bread. White kidney bean extract contains a natural alpha-amylase inhibitor, which holds back the enzyme that breaks starch down. In a 2026 review of 8 trials, adults taking it lost more weight and body fat than those on placebo.
This article is for you if: you've seen white kidney bean extract on a label and want to know what it does with a plate of rice or noodles, what the human trials found and when to take it.
White kidney bean extract has been tested in human trials with starchy meals and in weight management trials. Its effect is specific: it works on starch, by slowing the enzyme your body uses to break starch down. Here's how that works, what happened in the weight management trials, and how to time it around the rice and noodle meals that fill most Singapore days.
In this article
How does white kidney bean extract work?
White kidney bean extract slows starch digestion by inhibiting alpha-amylase, the enzyme that digests starch and other complex carbohydrates.[1] White kidney beans (Phaseolus vulgaris) are rich in a natural alpha-amylase inhibitor.[2]
When some of that enzyme is held back, the starch from your meal may be digested more slowly, or some of it may travel further down the gut as resistant starch (starch that isn't broken down in the small intestine).[3]
The extract works on starch, the carbohydrate in rice, noodles, bread and potatoes. Sweet drinks such as kopi with sugar get their carbohydrate mostly from sugar rather than starch, so starchy meals are where it fits best.
Does it stop you absorbing carbs?
It slows starch digestion rather than stopping it, so it takes the edge off a starchy meal. In a small test with 13 people, adding 3,000 mg of white bean extract powder to white bread lowered the bread's glycaemic index by about a third.[1] The glycaemic index is a measure of how quickly a food raises your blood sugar.
So the extract is best used alongside sensible portions. If you notice energy dips after a big lunch, our guide to glucose spikes and the 3pm slump has simple ways to steady your blood sugar.
What do weight management trials show?
Across several placebo-controlled trials, adults taking white kidney bean extract before meals lost more weight and body fat than those on placebo. Here's what each trial gave and found.
| Study | Who took part | Daily dose and length | Result compared with placebo |
|---|---|---|---|
| Celleno et al., 2007 | 60 slightly overweight adults | 445 mg, 1 tablet before a carb-rich main meal, 30 days | Greater drops in body weight, BMI, fat mass and waist, hip and thigh measurements |
| Wang et al., 2020 | 120 adults with obesity | 2,400 mg, split before each meal, 35 days | Lost about 2.7% of body weight vs 0.3% on placebo; waist and hip measurements also fell |
| Jäger et al., 2024 | 81 adults with overweight or moderate obesity, on a calorie-reduced diet | 2,100 mg or 3,000 mg, split before 3 meals, 12 weeks | 91.7% (higher dose) and 70.6% (lower dose) lost at least 3% of body weight, vs 14.7% on placebo; the higher dose took 3.94 cm off the waist vs 1.00 cm |
| Udani et al., 2018 (review) | 11 studies, 573 people | Most often 3,000 mg; two used 400 mg or 445 mg in blends | Greater weight loss and body fat reduction than placebo |
| Shi et al., 2026 (review) | 8 trials, 543 adults with overweight or obesity | Varied | Greater reductions in weight, BMI, fat mass, waist (1.58 cm) and hip measurements |
Sources: the published trials and reviews listed in the References. Wang et al. percentages are calculated from the reported start and end weights.[2] [3] [4] [5] [6]
The tablet in the Celleno trial also contained vitamin B3 and a small amount of chromium. The authors judged the chromium dose too small to affect body composition and credited the results to the bean extract.[3]
How does it fit around your meals?
Take it before your most starch-heavy meal, since that's when it has starch to act on. In the trials, people took it before meals, and in the 12-week trial, 30 minutes before.[4]
Our Lean Burn Pre+Probiotic Melts has 500 mg of white kidney bean extract per sachet. Take 1 to 2 sachets a day before meals, which is 500 to 1,000 mg a day. The trial closest to this amount is the 30-day Celleno study, which used 445 mg once a day before the main carb-rich meal.[3] Each sachet also has:
- 10 billion CFUs of probiotics from 3 strains: L. plantarum, L. fermentum and L. paracasei.
- 5 mg of L-arabinose, plus the prebiotic fibres fructo-oligosaccharides and inulin.
- A blood orange-flavoured powder that melts on your tongue, so you can take it with or without water.
For most of us in Singapore, the biggest starch hit comes at lunch or dinner: chicken rice, mee pok or a plate of fried bee hoon. A few habits help the extract do its job:
- Take it before your most starch-heavy meal of the day.
- Keep portions sensible, since the extract slows some starch digestion and the size of the plate still counts.
- Add protein and vegetables to rice and noodle dishes.
- Give it time. The trials ran from 30 days to 12 weeks.
For a wider look at what supports weight management, see whether slimming teas work and what does.
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Related reading: What brown seaweed extract does to carbs and fat · Glucose spikes and the 3pm slump · Are slimming teas a scam? What works for weight management
Frequently asked questions
Is white kidney bean extract safe?
Trials have found it well tolerated. A 2026 review of 8 trials reported no serious adverse events linked to the extract, and no adverse effects were seen in the 35-day Wang trial. Lean Burn Pre+Probiotic Melts contains milk, and if you're pregnant, breastfeeding or take medication, check with your doctor first.
Is it the same as eating kidney beans?
No. Raw or undercooked kidney beans contain substances that can upset your stomach, so they must always be cooked well. The extract in the Celleno trial was made with heat to largely switch off those substances while keeping its effect on starch digestion. Cooked beans are still a good source of fibre and protein in their own right.
Can I take it if I have diabetes or prediabetes?
Speak to your doctor first. White kidney bean extract affects how starch is digested, so it may change how your blood sugar responds to meals, especially if you take medicine that lowers blood sugar.
When will I see results?
The trials measured results after 30 days to 12 weeks. In the 30-day Celleno trial, the extract group had already lost more weight and fat mass than the placebo group by the end of the month. For the best results, take it daily for at least 3 months alongside steady habits.
Key takeaways
- White kidney bean extract contains a natural alpha-amylase inhibitor, which slows the digestion of starch.
- It works on starchy foods such as rice, noodles and bread, so take it before your most starch-heavy meal.
- In placebo-controlled trials, adults taking it before meals lost more weight and body fat than those on placebo.
- A 2026 review of 8 trials found greater reductions in weight, BMI, fat mass and waist size, with no serious adverse events.
- Lean Burn Pre+Probiotic Melts has 500 mg of white kidney bean extract per sachet, with 10 billion CFUs of probiotics.
About the author: Shereen is a Product Management Associate at The Purest Co. A Master's graduate in Pharmacy from Monash University, she brings four years of research experience to product development, with a focus on evidence-based, thoughtfully formulated supplements that support everyday wellbeing.
References
[1] Udani JK, Singh BB, Barrett ML, Preuss HG. Lowering the glycemic index of white bread using a white bean extract. Nutr J. 2009.
[2] Wang S et al. Regular intake of white kidney beans extract (Phaseolus vulgaris L.) induces weight loss compared to placebo in obese human subjects. Food Sci Nutr. 2020.
[3] Celleno L, Tolaini MV, D'Amore A, Perricone NV, Preuss HG. A dietary supplement containing standardized Phaseolus vulgaris extract influences body composition of overweight men and women. Int J Med Sci. 2007.
[4] Jäger R et al. Proprietary alpha-amylase inhibitor formulation from white kidney bean (Phaseolus vulgaris L.) promotes weight and fat loss: a 12-week, double-blind, placebo-controlled, randomized trial. Sci Rep. 2024.
[5] Udani J, Tan O, Molina J. Systematic review and meta-analysis of a proprietary alpha-amylase inhibitor from white bean (Phaseolus vulgaris L.) on weight and fat loss in humans. Foods. 2018.
[6] Shi N et al. White kidney bean extract reduces body weight and adiposity with acceptable safety in adults with overweight and obese: a systematic review and meta-analysis. Nutr Res. 2026.
These statements have not been evaluated by any regulatory authority. This product is not intended to diagnose, treat, cure, or prevent any disease. Individual results may vary. Consult a healthcare provider before use if you are pregnant, breastfeeding, or on prescribed medication.