White Kidney Bean Extract
A real starch blocker with a real effect, measured honestly in about a kilogram.
C-
Evidence grade
C-
Worth it
$12-20/month
Typical cost
DoseTrials used 500 to 3,000 mg/day of standardized extract taken before starch-containing meals; the effect, such as it is, only exists relative to starch actually eaten, so it does nothing alongside a low-starch meal. Product potency (amylase-inhibiting units) varies and is not uniformly labeled.
BasisWhite kidney bean extract does the thing it claims, slightly.
White kidney bean extract (Phaseolus vulgaris) contains an inhibitor of alpha-amylase, the enzyme that begins starch digestion. We grade White Kidney Bean Extract C- on evidence and C- for worth-it at about $12-20 per month.
What it does
White kidney bean extract (Phaseolus vulgaris) contains an inhibitor of alpha-amylase, the enzyme that begins starch digestion. It is sold as a 'carb blocker' for weight control, one of the few diet-category claims with an actual mechanism, graded here on what that mechanism has delivered in trials.
What the research says
Blocks some starch digestion and produced small weight losses in pooled trials
Evidence: emerging. The mechanism is real pharmacology: the extract inhibits alpha-amylase, some starch passes undigested, and calorie absorption falls slightly. Meta-analyses (Barrett and Udani 2011 and later poolings) find weight loss on the order of 1 to 2 kg over four to twelve weeks versus placebo, across small trials of uneven quality, several industry-funded. Undigested starch ferments in the colon, which is both the proof of mechanism and the side effect: gas, bloating, and loose stools are common.
White kidney bean extract does the thing it claims, slightly. A genuine enzyme inhibitor with a genuine, small, short-term weight effect pooled from mediocre trials, paid for in gastrointestinal discomfort and in the opportunity cost of every better-supported strategy in this library. C-: real, minor, and honestly labeled here in kilograms rather than in the category's usual adjectives.
Is it worth it?
Evidence (C-) sits below the leaderboard floor, so the worth-it grade is capped at C+ however inexpensive it is; the derived value lands at C-. About $16 a month at studied doses. Derived from the October 2026 worth-it model.
Typical cost
$12-20/month
Common form, not a brand recommendation
Dosage context established
Trials used 500 to 3,000 mg/day of standardized extract taken before starch-containing meals; the effect, such as it is, only exists relative to starch actually eaten, so it does nothing alongside a low-starch meal. Product potency (amylase-inhibiting units) varies and is not uniformly labeled.
Worth-it leaderboard
White Kidney Bean Extract sits outside the worth-it top 20.
White Kidney Bean Extract sits outside the current top 20 on the gated leaderboard. The leaders below clear an evidence floor of B- before price counts at all, so cheap alone never earns a rank.
- 1AWorth itCreatine evidence A-~$5-10/mo
- 2AWorth itCaffeine evidence B+~$5-10/mo
- 3AWorth itVitamin D evidence B~$5-8/mo
See the full worth-it leaderboard →
When the evidence moves a grade, this ranking moves with it. Thursday is where you hear it first.
Safety notes
GI effects are the common cost: flatulence, bloating, diarrhea, dose-related. Because it alters carbohydrate digestion, people using insulin or glucose-lowering drugs should treat it as active and monitor. Raw kidney beans are toxic (phytohemagglutinin); the extracts are processed and are not the bean, but anyone inspired to improvise with raw beans should not.
Longevity Lab Report
White Kidney Bean Extract news. Graded when it happens.
The grade on this page stays free. The email carries the news on white kidney bean extract: expert moves, dose changes, and what is working, in plain English every Thursday.
Changelog
Last updated 2026-10-23
- 2026-10-23|Graded from the weight-loss meta-analyses. White kidney bean closes Tier 3 of the grading queue as its most conventionally 'diet industry' entry, and the record holds it to the same standard as everything above it in the tier: pooled effect, trial quality, and the size of the number in kilograms.
- 2026-10-23|Not listed under any goal: the graded finding is a small short-term weight effect and the library's goals carry no weight category; the tag is not stretched to fit.
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This grade for White Kidney Bean Extract rests on the record above. When a new result changes that record, the grade changes with it, and the Thursday email is where the change lands first: the week's longevity and biohacking news, in plain English, linked back to the reasoning on this page.
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