Does Lactobacillus Gasseri Help Reduce Belly Fat? The Science & How to Use It
Updated August 23, 2026 · reviewed by the SodaLean Research Team
| What it is | Lactobacillus gasseri is a probiotic species that naturally lives in the human gut and mouth. |
| Belly-fat evidence | Trials of strains SBT2055 and BNR17 showed modest drops in abdominal fat and waist size over 8–12 weeks. |
| Important caveat | Effects are gentle, need consistency, and appear to fade after you stop — it is a habit, not a fat burner. |
| Label tip | Look for the exact strain code, CFU through the expiry date, and a paired prebiotic fibre. |
Few probiotics have generated as many "belly fat" headlines as Lactobacillus gasseri. It is one of the only gut bacteria with human trials that measured visceral fat — the deep abdominal fat wrapped around your organs — as a primary outcome. That makes it genuinely interesting, but it also makes it a magnet for exaggeration. This guide walks through what the research on Lactobacillus gasseri for belly fat actually found, the gut mechanism behind it, how much people used in the studies, and how to read a label so you know what you are really buying.
What is Lactobacillus gasseri?
Lactobacillus gasseri is a species of lactic-acid bacteria that naturally colonises the human digestive tract, mouth and other niches from early life. It belongs to the broad Lactobacillus family — the same group behind many fermented foods and traditional yoghurts. Compared with Bifidobacterium species, which dominate the large intestine, Lactobacillus species tend to be more active higher up in the small intestine, where much of nutrient absorption happens.
Like most probiotics, its effects are strain-specific. The two strains that put L. gasseri on the weight-management map are SBT2055 (sometimes written LG2055) and BNR17. When you read that "gasseri reduces belly fat," the claim almost always traces back to trials of one of these two specific strains — a detail that matters when you shop.
Lactobacillus gasseri and belly fat: what the studies found
Here is the honest picture. A handful of randomised, placebo-controlled human trials tested specific L. gasseri strains and measured body fat directly, often with imaging rather than a bathroom scale. The pattern that emerged was modest but real.
- ✓ SBT2055 trials reported measurable reductions in abdominal visceral and subcutaneous fat, body weight, waist and hip circumference over roughly 12 weeks in adults with excess abdominal fat, compared with placebo.
- ✓ BNR17 trials similarly reported reductions in waist circumference and body weight in overweight adults over 12 weeks.
- ✓ The effects were gentle. These were meaningful shifts on average, not dramatic transformations, and they happened alongside dietary awareness in the study settings.
- ✓ Benefits appeared to fade. In at least one SBT2055 study, the fat-related improvements diminished within about a month of stopping — a strong hint that L. gasseri does not permanently colonise the gut for most people.
The takeaway is not "a probiotic will flatten your stomach." It is that a specific, well-studied strain can nudge abdominal fat in the right direction when used consistently as part of a broader plan — and that you have to keep the habit for the benefit to persist.
How might Lactobacillus gasseri work?
No single mechanism fully explains the belly-fat findings, but researchers point to several plausible, overlapping pathways — all of them working with your gut rather than around it.
1. Less fat absorbed, more passed through
Some Lactobacillus strains appear to reduce the amount of dietary fat absorbed in the small intestine, so slightly more is excreted rather than stored. Even a small daily difference can add up over weeks.
2. Lower gut inflammation
Excess visceral fat is strongly linked with low-grade, whole-body inflammation that begins, in part, at a leaky gut barrier. By supporting the barrier and shifting the microbial balance, probiotics may dampen the inflammatory signalling associated with fat storage and insulin resistance. This is the same barrier-and-metabolite story we tell in our guide to butyrate and short-chain fatty acids.
3. Appetite and hormone signalling
Gut bacteria influence the hormones that govern hunger and fullness. Some research links L. gasseri and its metabolites to changes in appetite-related signalling, which could make it easier to eat to appetite rather than past it. We dig into that hormone pathway in our guide to increasing GLP-1 naturally.
A gut-first routine you can actually keep
SodaLean™ combines a live probiotic blend with chicory root inulin and potato resistant starch in one daily vegetarian capsule — backed by a 60-day money-back guarantee.
See SodaLean Packages
Because the belly-fat studies ran for 8–12 weeks, a 3- or 6-bottle supply matches how long these habits actually need to work.
How much Lactobacillus gasseri did the studies use?
There is no official dose, but the trials give useful anchors:
- ✓ SBT2055 studies commonly used on the order of 108 to 1010 colony forming units (CFU) per day — that is roughly hundreds of millions to around ten billion CFU daily.
- ✓ Duration mattered. Benefits were measured after 8 to 12 weeks of daily use, not after a few days.
- ✓ Blends share the total. In a multi-strain product the CFU is split across strains on purpose; a lower per-strain count is normal and not a defect.
- ✓ Keep it going. Because effects appear to fade after stopping, treat it as an ongoing daily habit.
Whatever product you choose, follow the label directions. SodaLean's routine is a single capsule with an 8 oz glass of water — simple enough to sustain for the weeks these benefits require.
What to look for on a Lactobacillus gasseri label
- ✓ The exact strain. Look for a strain code such as SBT2055 or BNR17, not just "L. gasseri." The strain is the identity of the bacterium that was actually studied.
- ✓ CFU at end of shelf life. Potency should be guaranteed through the expiry date, because live bacteria decline over time.
- ✓ A paired prebiotic. Fibre such as inulin or resistant starch feeds the bacteria — a synbiotic design.
- ✓ Realistic claims. Be wary of any label promising rapid or targeted fat loss. Honest products describe support, not miracles.
- ✓ Quality signals. An FDA-registered, GMP-certified facility and non-GMO sourcing reflect a serious maker.
For a full walkthrough, see how to read a gut health supplement label, and for how the whole microbiome ties to your waistline, how gut health affects weight loss.
Who should be cautious?
L. gasseri is a natural gut resident and is generally well tolerated by healthy adults, with occasional mild, temporary gas or bloating in the first days. As with any probiotic, anyone who is pregnant or nursing, under 18, immunocompromised, seriously ill, or managing a health condition or medication should consult a qualified healthcare professional before starting.
How to get the most from it
Give it the full runway. The studies ran 8 to 12 weeks; judge your results over months, not days.
Keep the habit. Because benefits fade after stopping, consistency is the whole game.
Stack the basics. A probiotic works best on a foundation of fibre-rich food, movement and sleep — the same habits that support the appetite hormones and metabolism L. gasseri may gently influence.
The bottom line
Lactobacillus gasseri is one of the more compelling probiotics for abdominal fat because it has actually been tested for it — with strains like SBT2055 and BNR17 showing modest, measurable reductions in visceral fat and waist size over a couple of months. But the honest framing is important: the effects are gentle, they require daily consistency, and they appear to fade if you stop. Used as an ongoing habit inside a sensible, fibre-rich, active lifestyle, a well-chosen L. gasseri strain can be a genuine supporting player. Sold as a shortcut to a flat stomach, it will only disappoint. Pick a product that names its strain, guarantees its CFU, and feeds the bacteria with prebiotic fibre.
This guide was written and fact-checked by the SodaLean Research Team — an independent group focused on gut health, metabolism and evidence-based weight management — and medically reviewed by Emily Gottfried. We read the primary research, translate it into plain language, and flag hype wherever we find it. We never promise miracle results, only clear, accurate information you can act on. Spotted something to correct? Email [email protected].
Frequently asked questions
Does Lactobacillus gasseri really reduce belly fat?
Some human trials of specific L. gasseri strains, notably SBT2055 and BNR17, reported modest reductions in abdominal (visceral) fat and waist circumference over roughly 8 to 12 weeks compared with a placebo. The effects were real but gentle, and they occurred alongside diet awareness. L. gasseri is a supportive habit, not a spot-reduction fat burner, and effects may fade if you stop taking it.
How long does it take for Lactobacillus gasseri to work?
In the studies that showed benefits, changes in abdominal fat and waist measurements were typically measured after about 8 to 12 weeks of daily use. Probiotics act on the gut ecosystem gradually, so consistency over a couple of months matters far more than any single dose.
What is the best strain of Lactobacillus gasseri for weight?
The two most-studied strains for body fat are SBT2055 (sometimes labelled LG2055) and BNR17. Findings from one strain do not automatically transfer to another, so the specific strain code on the label matters. A strain that is part of a broader gut-first blend can also contribute to the overall effect.
Does Lactobacillus gasseri come back after you stop taking it?
In at least one well-known trial, the fat-related benefits diminished about a month after participants stopped taking the probiotic, which suggests L. gasseri does not permanently colonise the gut for most people. That is why it is best treated as an ongoing daily habit rather than a short course.
Is Lactobacillus gasseri safe?
L. gasseri is a naturally occurring resident of the human gut and is generally well tolerated by healthy adults, with occasional mild, temporary gas or bloating early on. Anyone pregnant or nursing, under 18, immunocompromised or managing a medical condition should speak with a qualified healthcare professional before starting.
References
- Kadooka Y, et al. “Regulation of abdominal adiposity by probiotics (Lactobacillus gasseri SBT2055) in adults with obese tendencies: a randomized controlled trial.” European Journal of Clinical Nutrition, 2010.
- Kadooka Y, et al. “Effect of Lactobacillus gasseri SBT2055 in fermented milk on abdominal adiposity in adults in a randomised controlled trial.” British Journal of Nutrition, 2013.
- Kim J, et al. “Lactobacillus gasseri BNR17 supplementation reduces waist and hip circumference in overweight adults: a randomized, double-blind trial.” Journal of Functional Foods, 2018.
- Hill C, et al. “Expert consensus document: the ISAPP consensus statement on the scope and appropriate use of the term probiotic.” Nature Reviews Gastroenterology & Hepatology, 2014.
- Koh A, et al. “From dietary fiber to host physiology: short-chain fatty acids as key bacterial metabolites.” Cell, 2016.
† These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease. This article is for general information only and is not medical advice; consult a qualified healthcare professional before making changes to your diet or supplement routine.