Written by Shereen, Product Management Associate · Updated 11 November 2026
Can postbiotics help reduce belly fat?
One postbiotic strain has promising results. In a 3-month placebo-controlled trial, adults carrying extra weight around the middle who took a daily capsule of heat-treated Bifidobacterium animalis subsp. lactis CECT 8145 had a greater drop in waist size than the placebo group, and their visceral fat fell over the study. It works alongside healthy habits.
This article is for you if: you've seen postbiotics on a label and want to know what they are, how they differ from probiotics, and what the research on belly fat actually found.
Postbiotics sit alongside prebiotics and probiotics, and scientists now have an agreed definition for them.[1] One postbiotic, a heat-treated form of the bacterium Bifidobacterium animalis subsp. lactis CECT 8145, has been tested in a placebo-controlled trial in adults carrying extra weight around the middle. Here's what postbiotics are, what that trial found, how non-living bacteria might affect belly fat, and where they fit in your routine.
In this article
What are postbiotics?
A postbiotic is "a preparation of inanimate microorganisms and/or their components that confers a health benefit on the host", according to the international expert panel that agreed the definition.[1] In plain words, postbiotics are beneficial microbes that are no longer alive, or parts of them, that still do something useful. Probiotics, by contrast, are live microorganisms.
To count as a postbiotic, a preparation must contain inactivated microbial cells or cell components, with or without the substances they produce.[1] In the belly fat trial below, the bacteria were inactivated by heating them to 121°C for 30 minutes.[2]
If you're new to the topic, start with our guide to postbiotics and how they relate to pre- and probiotics, or the difference between prebiotics and probiotics.
What did the postbiotic belly fat trial find?
In a 3-month trial, the heat-treated form of B. lactis CECT 8145 reduced waist size more than placebo in adults with abdominal obesity, and their visceral fat fell over the study.[2]
The study was a randomised, double-blind, placebo-controlled trial from Spain. It recruited adults with abdominal obesity, meaning a waist of at least 102 cm for men or 88 cm for women. Of 135 people enrolled, 126 (43 men and 83 women) received one capsule a day for 3 months:[2]
- a placebo (maltodextrin),
- the live probiotic form of B. lactis CECT 8145, or
- the same strain in heat-treated (postbiotic) form.
Each active capsule held 10 billion cells, counted before heat treatment for the postbiotic. Visceral fat, the deeper fat around the organs, was measured by MRI. Diet and physical activity were similar across the groups, though the heat-treated group ate more fibre than the placebo group.[2]
| Measure after 12 weeks | Heat-treated (postbiotic) | Live (probiotic) |
|---|---|---|
| Waist circumference | Down 1.84 cm on average; significant compared with placebo | Down 1.75 cm on average; a trend compared with placebo |
| Waist-to-height ratio | Down; significant compared with placebo | Down; a trend compared with placebo |
| Visceral fat area (MRI) | Down 7.01 cm²; significant from the start of the study, borderline compared with placebo | Down 3.66 cm²; not significant |
| Blood markers | Diastolic blood pressure and insulin resistance (HOMA-IR) fell from the start of the study | No significant change reported |
Sources: the published trial and its full text.[2]
The authors concluded that the strain, "both as viable and mainly as heat-killed cells", improved measures of body fat in people with abdominal obesity, particularly women.[2] The live form also lowered body mass index compared with placebo, and for waist and visceral fat, the largest reductions came with the heat-treated form.
How could non-living bacteria affect belly fat?
Researchers have three main leads, and the first points to a structural part of the bacterium rather than live activity.
- The cell wall itself. In a lab study using tiny worms (C. elegans), a component of this strain's cell wall called lipoteichoic acid was responsible for its fat-reducing effect, acting through a signalling route called the IGF-1 pathway. The study used the same strain, also known as BPL1.[3]
- The immune system. The trial authors noted that mechanisms proposed for heat-treated bacteria include regulation of the host's immune system.[2]
- Gut bacteria. Levels of Akkermansia, a gut bacterium that was inversely related to body weight in the trial, rose after treatment, particularly with the live form.[2]
The wider field is growing. A 2024 systematic review of 49 studies (9 in people and 40 in animals) found that heat-killed strains taken by mouth, including CECT 8145, improved body composition and body measurements, and concluded that postbiotics seem to be a safe intervention.[4]
Where do postbiotics fit in your routine?
A postbiotic works alongside the basics, not instead of them. Meals built around vegetables, wholegrains and protein, regular movement and enough sleep remain the foundation for a healthy waistline.
Our Sicilian Orange Slimming Elixir and Sicilian Orange Slimming Elixir Zero each contain 10 billion postbiotic cells of B. lactis CECT 8145 per sachet. That's the strain from the trial, in the heat-treated form that gave the largest drops in waist size and visceral fat.[2] Each sachet also has 400 mg of Morosil®, the Moro blood orange extract studied for weight management, and 500 mg of L-carnitine (see does L-carnitine help you lose weight?). Take 1 sachet a day, about 30 minutes before a meal, and give it at least the 3 months the trial ran.
If you're pregnant, breastfeeding, on medication or have a health condition, including one that affects your immune system, check with your doctor first.
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Related reading: Postbiotics explained: the next step after pre- and probiotics · Does blood orange extract help with weight management? · Does L-carnitine help you lose weight?
Frequently asked questions
Are postbiotics the same as probiotics?
No. Probiotics are live microorganisms, while postbiotics are inactivated microbes or their components. In the CECT 8145 trial, the same strain was tested both ways, and the heat-treated form produced the largest drops in waist size and visceral fat.
Do postbiotics work for men as well as women?
The trial included 43 men and 83 women. When the researchers analysed each sex separately, the results stayed significant for women. The authors noted that the smaller number of men may explain why the changes in men did not reach significance on their own.
How long does it take to see a difference?
The trial measured results after 12 weeks of daily use. Measuring your waist every few weeks is a more useful check than the scale, because it tracks the fat around your middle.
Are postbiotics safe to take every day?
A 2024 systematic review of 49 studies concluded that postbiotics seem to be a safe intervention, and the belly fat trial gave a capsule every day for 3 months. As with any supplement, check with your doctor first if you're pregnant, breastfeeding, taking medication or have a health condition, including one that affects your immune system.
Key takeaways
- A postbiotic is a preparation of inactivated microbes, or their components, that confers a health benefit.
- In a 3-month placebo-controlled trial, heat-treated B. lactis CECT 8145 reduced waist size more than placebo in adults with extra weight around the middle.
- Visceral fat fell over the study with the heat-treated form, and the largest drops in waist size and visceral fat came with the heat-treated form rather than the live one.
- Lab research points to a part of the strain's cell wall, lipoteichoic acid, as one driver.
- Sicilian Orange Slimming Elixir and Sicilian Orange Slimming Elixir Zero contain 10 billion postbiotic cells of this strain per sachet.
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] Salminen S et al. The International Scientific Association of Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of postbiotics. Nat Rev Gastroenterol Hepatol. 2021.
[2] Pedret A et al. Effects of daily consumption of the probiotic Bifidobacterium animalis subsp. lactis CECT 8145 on anthropometric adiposity biomarkers in abdominally obese subjects: a randomized controlled trial. Int J Obes (Lond). 2019.
[3] Balaguer F et al. Lipoteichoic acid from Bifidobacterium animalis subsp. lactis BPL1: a novel postbiotic that reduces fat deposition via IGF-1 pathway. Microb Biotechnol. 2022.
[4] Eslami M et al. The anti-obesity effects of postbiotics: a systematic review of pre-clinical and clinical studies. Clin Nutr ESPEN. 2024.
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.