Lactobacillus Gasseri
Marketed hard as a "belly fat probiotic" on the strength of two Japanese fermented-milk trials of strain SBT2055. The weight loss in those trials was about 1 kg over 12 weeks, it reversed completely after stopping, and independent replication in other populations is thin.
What the science says
- Reduces abdominal visceral fat Limited evidence
In a 12-week RCT of 87 adults with obese tendencies, fermented milk with L. gasseri SBT2055 at 100 million CFU/g reduced visceral fat area by about 4.6% and body weight by roughly 1.4% versus essentially no change on placebo. A larger 210-person trial confirmed similar magnitude (visceral fat area down 8.5% at 10 billion CFU/day), but abdominal fat returned toward baseline within 4 weeks of stopping.
- Produces clinically meaningful weight loss Limited evidence
The best-case result is roughly 1-1.5 kg over 12 weeks — below the ~5% threshold generally considered clinically meaningful, and smaller than what a modest calorie deficit achieves. Trials were conducted in Japanese adults using a dairy vehicle and mostly funded by the dairy manufacturer; results in Western populations and in capsule form are far less consistent.
- Supports vaginal and urogenital health Limited evidence
L. gasseri is a normal dominant species of the healthy vaginal microbiome and appears in multi-strain products for bacterial vaginosis recurrence, but trials are small, heterogeneous and usually combine it with L. rhamnosus or L. crispatus, so a specific effect for gasseri alone is not established.
- Suppresses appetite via leptin or GLP-1 Limited evidence
Mechanistic claims come from rodent studies and in vitro work showing altered fat emulsion size and increased fecal fat excretion. No human trial has shown meaningful appetite suppression, and this marketing angle outruns the data badly.
Dosage & safety
How to take it
Interactions
With medications
- antibiotics
Antibiotics kill the live organisms if taken together. separate doses by about 2 hours
- immunosuppressants and treatments causing neutropenia
Rare probiotic bacteremia is reported in severely immunocompromised and catheterized patients. avoid unless your specialist approves
Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.
Frequently asked questions
Does Lactobacillus gasseri reduce belly fat?
The evidence is limited: in Japanese trials of L. gasseri SBT2055 in fermented milk, visceral fat area fell by about 4.6-8.5% over 12 weeks, but abdominal fat returned toward baseline within 4 weeks of stopping. The trials were mostly funded by the dairy manufacturer.
How much weight can you lose with Lactobacillus gasseri?
The best-case result for Lactobacillus gasseri is roughly 1-1.5 kg over 12 weeks, below what is considered clinically meaningful and smaller than a modest calorie deficit achieves. Results in Western populations and in capsule form are far less consistent.
Does L. gasseri suppress appetite?
No human trial has shown meaningful appetite suppression from Lactobacillus gasseri; the leptin and GLP-1 claims come from rodent and test-tube work. That marketing angle outruns the data badly.
How should I take Lactobacillus gasseri?
The SBT2055 trials used fermented milk supplying roughly 10 billion CFU/day, split into two servings with meals, for 12 weeks. Because the effect of Lactobacillus gasseri vanished within about 4 weeks of stopping, it is an indefinite habit with a small expected payoff, not a course.
Scientific references
Where to buy
Humanx, Lactobacillus Gasseri & Reuteri+, 30 Veggie Capsules
Ships to 180+ countries · welcome discount for new customers
Referral link — this site may earn a commission on purchases.
Related in Weight management
- L-Carnitine Moderate evidence
- MCT Oil Moderate evidence
- CLA (Conjugated Linoleic Acid) Limited evidence
- White Kidney Bean Extract Limited evidence
- Glucomannan Limited evidence
- Chitosan Limited evidence