Which Named Probiotic Strain Actually Helps With Weight?

Best Probiotic Products With Named Weight-Management Strains: B420, SlimBiotics, L. gasseri, and CGMCC1.3724 Compared

Four named strains anchor most weight-management probiotic marketing: B420, the three-strain SlimBiotics® blend, several distinct L. gasseri strains, and CGMCC1.3724. Each has its own small human trial with modest, mixed results, and the retail products built on them differ widely in dose and in how closely they match what was actually tested.

Why the exact strain code is the only thing worth checking

"Contains L. gasseri" or "with clinically studied probiotics" tells you almost nothing. Probiotic effects are strain-specific, not species-specific, which means a trial on Lactobacillus gasseri SBT2055 says nothing about a bottle that lists plain "L. gasseri" with no strain code. The four strains in this article, Bifidobacterium animalis subsp. lactis 420 (B420), the SlimBiotics® trio of Lactobacillus fermentum strains, coded L. gasseri strains like SBT2055 and BNR17, and Lacticaseibacillus rhamnosus CGMCC1.3724 (also called LPR), are among the few weight-related strains with a published randomized trial behind the exact code. It's a low bar, though: these are mostly single, small, industry-funded trials, not a body of independently repeated evidence. Treat every claim below as an early human signal, not proof.

B420 (Bifidobacterium animalis subsp. lactis 420)

B420 is the most-cited strain in this category, mainly because of one 225-person, six-month randomized trial (Stenman 2016).¹ Participants drank a daily smoothie with a placebo, a 12 g/day polydextrose fiber, B420 alone (10¹⁰ CFU/day), or B420 plus the fiber. The trial's pre-specified primary endpoint, change in DXA-measured body fat mass across all four groups, was not significant (P = 0.46). Inside the smaller per-protocol group, B420 plus fiber lost significantly more fat than placebo (about −4.5%, P = 0.02), but B420 alone did not (−3.0%, P = 0.28). A separate, unblinded, after-the-fact analysis that pooled both B420 arms against both non-B420 arms did find a significant difference (−4.0% fat, −2.4 cm waist, P = 0.002 and 0.004), but that comparison was run only after the trial was unblinded and never compared the B420-alone arm against the B420-plus-fiber arm directly. DuPont Nutrition & Health, now part of IFF,² funded the trial, and five of fifteen authors were DuPont employees.¹

Two examples show how differently this strain reaches the shelf. Metagenics UltraFlora Control sells it as a single-strain capsule, 10 billion CFU of B-420, one per day, through licensed-provider portals and third-party retailers.³ That's the same dose used in the trial; other single-strain B420 capsules on the market, such as Lean Gut Bugs and ProbioContour, also list the same 10-billion-CFU dose. WonderBiotics Probiotics for Weight Management uses B420 as one of eight named strains inside a 20-billion-CFU blend, alongside HN019, NCFM, L. rhamnosus GG, and four others, plus a separate Metabolic Blend built around dihydroberberine and a standardized lemon extract (Eriomin®).⁴ The single-strain B420 dose inside that eight-strain blend isn't broken out on the label, so you can't confirm it matches the 10¹⁰ CFU/day used in the trial. Every multi-strain product on this list has the same undisclosed-dose problem.

SlimBiotics: a three-strain blend built around one specific claim

SlimBiotics® is the trademark for three Lactobacillus fermentum strains (K7-Lb1, K8-Lb1, K11-Lb3) developed with Slimbiotics GmbH. The main human trial, a 180-person randomized study by Laue and colleagues (2023),⁵ tested the three strains alone against a synbiotic version (same strains plus acacia fiber) and a placebo over a 12-week (three-month) trial, with body fat mass by bioelectrical impedance as the pre-specified primary endpoint. The probiotic-only arm hit that primary endpoint: fat mass dropped 0.61 kg versus a 0.13 kg gain on placebo (P = 0.039), with secondary improvements in weight (P = 0.012), waist circumference (P = 0.033), and ultrasound-measured visceral fat (P < 0.001). The synbiotic arm, oddly, missed the fat-mass endpoint (P = 0.73, a small increase) even though its visceral fat result was significant (P = 0.002), a mismatch the researchers didn't fully explain. Slimbiotics GmbH funded the trial, and one author is a co-inventor on the strain patent and a paid consultant to the company.

The retail product carrying these three strains is Culturelle Metabolism + Weight Management with SlimBiotics®, $26.99 for a 30-day, one-capsule-per-day supply.⁶ The retail capsule isn't identical to the formula that was tested. Culturelle's own product page is inconsistent about the count: the headline says "4 powerful probiotic strains" (the SlimBiotics trio plus Lacticaseibacillus rhamnosus GG), but its Key Ingredients text also lists Bifidobacterium animalis subsp. lactis CECT 8145 (BPL1) as part of the 12-billion-CFU blend, which would make five named strains total. Either way, the SlimBiotics trial tested only the three L. fermentum strains on their own, without GG or BPL1. BPL1 has its own separate trial, but the significant waist and visceral-fat results in that study belonged to a heat-killed version of the strain, not the live form Culturelle uses.⁷ The finished capsule hasn't itself been through a trial, which is also true of B420 in every multi-strain product in this article.

L. gasseri: one species name covers several different products

L. gasseri shows up across at least three unrelated strain codes in weight-management products, plus a fair number of labels that just say "L. gasseri" with no code at all. Treating those as interchangeable is the single easiest mistake to make when strain-shopping.

SBT2055 has the longest track record, from two trials by the same Japanese dairy company: an 87-person 2010 study showing within-group drops in visceral and subcutaneous fat (4.6% and 3.3%),⁸ and a 210-person 2013 follow-up where visceral fat, the trial's own pre-specified primary endpoint, was significantly lower than placebo at both doses tested (P < 0.05), though the two doses performed about the same, with no clear dose-response, and the effect faded within about four weeks of stopping.⁹ The trial dose was 200 g/day of fermented milk; the manufacturer's own viable-cell counts for the two dose groups averaged 6.9 × 10⁶ and 7.9 × 10⁷ CFU/g, or roughly 1.4 and 15.8 billion CFU/day. Provitalize, sold by BB Company, lists SBT2055 at 1 billion CFU per serving alongside two other strains and a turmeric-and-moringa blend.¹⁰ That's below both doses tested in the trial, closest to about 70% of the low-dose group.

BNR17 comes from a 90-person, 12-week trial (Kim 2018) testing two doses against placebo.¹¹ Only the high dose (10¹⁰ CFU/day) beat placebo on visceral fat (−21.6 cm², P = 0.012). Waist circumference shrank in both dose groups compared to their own baseline, but neither dose beat placebo on that measure between groups, a distinction worth holding onto since marketing copy often blurs it. Bioneer's Korean affiliate AceBiome licensed BNR17 to UAS Labs for the U.S. market in 2018.¹² One product built around it is Daily Nouri Weight Health, which combines L. gasseri BNR-17 with L. plantarum UALp-05 and L. rhamnosus GG at $19.98 for a one-capsule, 30-day supply; per-strain CFU isn't disclosed.¹³

Uncoded L. gasseri is the third category, and it's the one to be most skeptical of. Physician's Choice THIN 30 lists plain "L. gasseri" among six strains and attributes fat-absorption and waist-circumference benefits to it directly on the product page, without citing a specific strain code or trial.¹⁴ That claim can't be tied to either the SBT2055 or BNR17 data above, because there's no way to confirm which strain, if any coded one at all, is actually in the capsule.

CGMCC1.3724 (the "LPR" strain): real data, hard to buy by name

CGMCC1.3724, also referred to as LPR, is Lacticaseibacillus rhamnosus dosed at about 3.2 × 10⁸ CFU/day (two capsules of 1.6 × 10⁸ CFU each, with an oligofructose-and-inulin prebiotic) in a 2014 trial (Sánchez et al.) of 153 adults who followed a moderate energy-restricted diet for the first 12 weeks and a weight-maintenance diet for the next 12.¹⁵ Nestlé Research Center sponsored the trial, contributed to the study design, ran the sample analyses, and helped prepare the manuscript; several authors were Nestlé Research Center staff. Twenty-eight of the 153 randomized participants were excluded after randomization for dyslipidemia, and the trial's own intention-to-treat analysis, run on the remaining 125, found no significant difference in weight loss between LPR and placebo overall. The signal that exists is confined to a women-only subgroup: 12-week weight loss of 1.8 kg versus placebo (P = 0.02), a gap that widened by 24 weeks (P = 0.02), and a fat-mass difference at 24 weeks (−4.79 kg versus −2.16 kg, P = 0.01). Men in the same trial showed no effect (P = 0.53 at 12 weeks). Both sexes were on the same energy-restricted diet, and the active arm also contained the prebiotic alongside the strain, so the weight loss can't be pinned on LPR by itself. The trial also explicitly excluded postmenopausal women, which limits how far the women's-subgroup finding extends for a 40-to-60-year-old reader.

As of this search in August 2026, no widely available, clearly labeled U.S. direct-to-consumer supplement markets this strain by its CGMCC1.3724 or LPR code the way UltraFlora Control markets B420 or Daily Nouri markets BNR17.

Strain-by-strain snapshot

Where WonderBiotics fits if you're strain-shopping

WonderBiotics Probiotics for Weight Management includes B420 as one of eight named strains, alongside HN019, NCFM, L. rhamnosus GG, and four other named strains, plus the separate Metabolic Blend built around dihydroberberine and Eriomin-brand eriocitrin, an ingredient with its own published human trial showing improved glycemic markers in prediabetic adults (that trial did not measure weight or body composition).¹⁶ The B420 data is one modest, industry-funded signal, not a proven single-ingredient solution, so we paired it with other named, clinically studied strains and a second ingredient targeting a different metabolic pathway instead of betting the whole formula on one strain hitting a per-protocol result again. Like every multi-strain product in this article, we publish the blend's total CFU count rather than a per-strain breakdown, the standard trade-off of combining eight strains instead of isolating one at its exact trial dose. For broader strain coverage plus a second ingredient with its own separate human trial data, that's what WonderBiotics Probiotics for Weight Management offers.

How to choose based on what you're optimizing for

• Want the exact trial dose in one capsule: UltraFlora Control (B420, 10B CFU) is the closest single-strain match on this list.
• Want broader strain coverage plus a second evidenced ingredient: WonderBiotics Probiotics for Weight Management pairs B420 with seven other named strains and the Eriomin-based Metabolic Blend.
• Want the SlimBiotics data specifically: know that Culturelle's retail version adds one or two strains not in the tested formula, depending on which part of the label you read.
• Considering an L. gasseri product: check for a strain code before you buy; "L. gasseri" alone isn't evidence of anything.
• Looking for CGMCC1.3724 by name: expect to come up empty in mainstream U.S. retail as of this writing.

Safety notes before you add any of these

None of these strains are treatments for obesity, and none of the trials above tested people on GLP-1 medications like semaglutide or tirzepatide. If you're on a prescription weight-loss medication, are pregnant or breastfeeding, or are immunocompromised, talk to your doctor before adding any probiotic, and never stop a prescribed medication to try a supplement instead. If you take an oral medication with specific timing instructions, follow those instructions and ask your pharmacist whether this supplement needs to be taken separately from it.

References

1. Stenman LK, Lehtinen MJ, Meland N, et al. Probiotic With or Without Fiber Controls Body Fat Mass, Associated With Serum Zonulin, in Overweight and Obese Adults: Randomized Controlled Trial. EBioMedicine. 2016;13:190-200. PMC5264483
2. IFF Health Sciences. HOWARU® B420 product page. iff.com
3. Metagenics. UltraFlora Control product page. metagenics.com
4. WonderBiotics. WonderBiotics Probiotics for Weight Management product page. wonderbiotics.com
5. Laue C, Papazova E, Pannenbeckers A, Schrezenmeir J. Effect of a Probiotic and a Synbiotic on Body Fat Mass, Body Weight and Traits of Metabolic Syndrome in Individuals with Abdominal Overweight: A Human, Double-Blind, Randomised, Controlled Clinical Study. Nutrients. 2023;15(13):3039. PMC10346309
6. Culturelle. Metabolism + Weight Management with SlimBiotics® product page. culturelle.com
7. Pedret A, Valls RM, Calderón-Pérez L, et al. Effects of daily consumption of the probiotic Bifidobacterium animalis subsp. lactis CECT 8145 on anthropometric adiposity biomarkers. Int J Obes. 2019;43(9):1863-1868. PMID 30262813
8. Kadooka Y, Sato M, Imaizumi K, et al. Regulation of abdominal adiposity by probiotics (Lactobacillus gasseri SBT2055) in adults with obese tendencies in a randomized controlled trial. Eur J Clin Nutr. 2010;64(6):636-643. PMID 20216555
9. Kadooka Y, Sato M, Ogawa A, et al. Effect of Lactobacillus gasseri SBT2055 in fermented milk on abdominal adiposity in adults in a randomised controlled trial. Br J Nutr. 2013;110(9):1696-1703. PMID 23614897
10. BB Company. Provitalize product page. thebbco.com
11. Kim J, Yun JM, Kim MK, Kwon O, Cho B. Lactobacillus gasseri BNR17 Supplementation Reduces the Visceral Fat Accumulation and Waist Circumference in Obese Adults: A Randomized, Double-Blind, Placebo-Controlled Trial. J Med Food. 2018;21(5):454-461. PMID 29688793
12. NutraIngredients-USA. UAS Labs licenses BNR17 probiotic strain for weight management. 2018. nutraingredients.com
13. Daily Nouri. Weight Health product page. dailynouri.com
14. Physician's Choice. THIN 30 product page. get.physicianschoice.com
15. Sánchez M, Darimont C, Drapeau V, et al. Effect of Lactobacillus rhamnosus CGMCC1.3724 supplementation on weight loss and maintenance in obese men and women. Br J Nutr. 2014;111(8):1507-1519. PMID 24299712
16. Ribeiro CB, Ramos FM, Manthey JA, Cesar TB. Effectiveness of Eriomin® in Managing Hyperglycemia and Reversal of Prediabetes Condition: A Double-Blind, Randomized, Controlled Study. Phytother Res. 2019;33(7):1921-1933. PMID 31183921