Scientists reviewed 40 animal studies to see if postbiotics—special compounds made by gut bacteria—could help with weight loss and metabolism. Animals that received postbiotics lost weight, had less body fat, and showed improvements in cholesterol and blood sugar levels. The researchers found that certain types of postbiotics worked better than others, especially when given in higher doses for at least 8 weeks. While these results are promising, the scientists say more research in humans is needed before we know if postbiotics can safely help people lose weight.

The Quick Take

  • What they studied: Whether special compounds called postbiotics (made by helpful gut bacteria) could help animals lose weight and improve their metabolism
  • Who participated: 40 different animal studies were combined in this analysis. The studies used various animal models of obesity to test postbiotics
  • Key finding: Animals given postbiotics lost weight, reduced body fat, and improved their cholesterol and blood sugar levels. The improvements were statistically significant, meaning they weren’t due to chance
  • What it means for you: This research suggests postbiotics might eventually help humans with weight management and metabolic health, but we need human studies first to confirm safety and effectiveness. Don’t expect postbiotics to be a magic solution—they appear to be one tool among many for health

The Research Details

This was a meta-analysis, which means researchers searched four major scientific databases for all animal studies about postbiotics and obesity published through May 2025. They found 40 studies that met their criteria. The researchers then combined all the data from these 40 studies using special statistical methods to see the overall effect of postbiotics.

The scientists used a tool called OHAT to check the quality and potential bias in each study. They looked at whether the studies were well-designed and if the results were trustworthy. They also performed additional analyses to understand which types of postbiotics worked best, what doses were most effective, and how long the treatment needed to last.

Postbiotics are different from probiotics—they’re the beneficial compounds that gut bacteria produce, rather than the bacteria themselves. The researchers looked at different forms of postbiotics, including short-chain fatty acids (SCFAs), which are compounds created when bacteria break down fiber.

This research approach is important because it combines evidence from many studies to get a clearer picture than any single study could provide. By analyzing 40 animal studies together, the researchers could identify patterns and determine which postbiotics and doses were most effective. This type of analysis helps scientists decide whether human studies are worth pursuing and what approaches might work best.

This is a systematic review and meta-analysis, which is considered high-quality evidence for summarizing existing research. However, all 40 studies were conducted in animals, not humans, so the results may not directly apply to people. The researchers assessed bias in the included studies, which strengthens the reliability of their conclusions. The fact that results were consistent across multiple studies increases confidence in the findings.

What the Results Show

Animals receiving postbiotics showed significant decreases in body weight and body fat compared to control animals. The improvements in metabolic markers were also notable: animals had lower levels of LDL cholesterol (the ‘bad’ cholesterol), triglycerides (a type of fat in the blood), total cholesterol, and fasting blood sugar. They also showed improvements in insulin levels and insulin resistance (measured by HOMA-IR, a test that shows how well the body uses insulin). Additionally, animals had higher levels of HDL cholesterol (the ‘good’ cholesterol).

Interestingly, the postbiotics didn’t significantly change how much food the animals ate. This suggests the weight loss happened through other mechanisms, such as improved metabolism or changes in how the body stores fat, rather than simply eating less.

When researchers looked at different types of postbiotics, short-chain fatty acids (SCFAs) appeared to be particularly effective. Higher doses (at least 100 mg per kilogram of body weight) and longer treatment periods (at least 8 weeks) produced better results than lower doses or shorter durations.

The analysis revealed that the benefits of postbiotics were consistent across different animal models and study designs, suggesting the effects are fairly robust. The improvements in insulin resistance and blood sugar control were especially notable, as these are key factors in metabolic health and obesity-related diseases. The reduction in inflammation markers (implied by the metabolic improvements) suggests postbiotics may work by reducing obesity-related inflammation in the body.

This research builds on growing interest in the gut microbiome’s role in weight management. Previous studies have shown that probiotics (live beneficial bacteria) have modest effects on weight, but postbiotics (the compounds these bacteria produce) may be more stable and easier to use. This meta-analysis is one of the first to comprehensively review postbiotics specifically for obesity, making it an important addition to the research landscape.

The biggest limitation is that all studies were conducted in animals, primarily rodents. Animal metabolism differs from human metabolism in important ways, so results may not directly translate to people. Additionally, the studies used various types of postbiotics, doses, and treatment durations, which creates some inconsistency. The researchers couldn’t assess long-term effects because most animal studies lasted only a few weeks. Finally, the mechanisms by which postbiotics work aren’t completely understood, so we can’t fully explain why they’re effective.

The Bottom Line

Based on this animal research, postbiotics show promise for weight management and metabolic health (moderate confidence level). However, human clinical trials are essential before making recommendations for people. If you’re interested in postbiotics, wait for human studies to confirm safety and effectiveness. In the meantime, proven strategies like balanced nutrition, physical activity, and adequate sleep remain the best approaches for weight management.

This research is most relevant to scientists and healthcare providers developing new obesity treatments. People struggling with weight management may find this interesting, but shouldn’t expect postbiotics to be available as a proven treatment yet. People with metabolic disorders, prediabetes, or obesity should continue following their doctor’s current recommendations rather than seeking out postbiotics.

In the animal studies, significant improvements appeared within 8 weeks. However, human studies would likely need several months to show meaningful results. Even if postbiotics eventually become available for humans, benefits probably wouldn’t appear overnight—consistent use over weeks to months would likely be necessary.

Want to Apply This Research?

  • Once postbiotics become available for human use, track weekly body weight, waist circumference, and energy levels. Also monitor digestive health and any changes in appetite or food cravings, as these may indicate the postbiotics are working
  • When postbiotics become available, pair them with consistent tracking of meals and physical activity. Use the app to log when you take postbiotics and correlate this with changes in weight, energy levels, and metabolic markers like blood sugar if you’re monitoring those
  • Establish a baseline of current weight, body composition, and metabolic markers (if available through your doctor). Then, if using postbiotics in the future, check these measurements monthly and track trends over 8-12 weeks, which aligns with the effective treatment duration found in animal studies

This research was conducted in animals and has not been tested in humans. Postbiotics are not currently approved as a medical treatment for obesity or metabolic disorders. Do not use postbiotics as a substitute for proven weight management strategies or medical treatment. Always consult with your healthcare provider before starting any new supplement or treatment, especially if you have obesity, diabetes, or other metabolic conditions. The findings presented here are preliminary and require human clinical trials before any recommendations can be made for people.