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Clinical Pearls: Probiotics and Weight Loss

Published about 18 hours ago • 3 min read

This week's topic: Probiotics and Weight Loss

The content in this email is from one of the Collective's Wisdom Wednesdays.

I was perusing probiotic options for a patient who wanted a probiotic that may help her gut and help with weight loss.

Normally, I would focus on boosting bifidobacterium species and balancing the Firmicutes:Bacteroidetes ratio, but I got curious and wanted to see what the research shows on over-the-counter probiotic nutraceuticals. And there were a LOT of probiotic brands that claimed to support weight loss.

Overview of today's email:

  1. Overview
  2. Top 3 species of probiotics that may be helpful

1. Overview

What is the evidence behind various probiotics that are promoted for supporting weight loss?

First, the mechanism of action (MOA) behind how probiotics may help with weight loss. According to the literature, probiotics may:

  1. Support gut barrier function (which lowers systemic inflammation)
  2. Lower inflammation locally in the gut lumen
  3. Increase microbiome diversity
  4. Improve insulin sensitivity
  5. Regulate appetite and SCFA production

Here are some of my findings, with a focus on human studies that don’t appear to have a conflict of interest...

2. Top 3 species of probiotics that may be helpful

Bifidobacterium lactis B420

This has the most clinical trials that show it can decrease body fat mass in the trunk and belly area, as well as reduce weight circumference. It works best if taken with prebiotic fibers. This 2016 RCT study had participants taking it for 6 months.

Products that have this: Metagenics Ultraflora Complete, Metagenics Triplebiotic with Akkermansia, and Nordic Flora Probiotic Immune. The last 2 on this list have a prebiotic added to the formula. All are available on Fullscript.

Review to peruse (from 2020): Bifidobacterium animalis subsp. lactis 420 for Metabolic Health: Review of the Research​

Lactobacillus gasseri (particular strains)

Specific strains (e.g. SBT2055 and BNR17) have consistent evidence for reducing visceral fat and overall body weight with 12 weeks of use. (2018 RCT)

Products that have this: Biothin Probiotics by Dr. Mercola

Review to peruse: Effect of different doses of Lacticaseibacillus paracasei K56 on body fat and metabolic parameters in adult individuals with obesity: a pilot study (2023)

Akkermansia mucinophila WST01

Benefits of this on weight may be dependent on baseline levels in the body prior to taking, and if there is known metabolic imbalances (e.g. insulin resistance). Also, most studies seem to look at use of this with a prebiotic.

Some references: 2025 article on a 12-week double-blind placebo controlled trial on 58 overweight patients with T2DM; 2026 RCT on 70 people for 8 weeks

Products that have this: Pendulum (most well known), but some Metagenics, Designs for Health, and Codeage products also have this (although the specific strain is not provided in these last 3 companies).

Resources to peruse:

Clinical Pearl: I have not seen a lot of benefit with Pendulum (akkermansia) in patients. However, per some studies, individuals with low baseline Akkermansia +/- metabolic imbalances are the ones most likely to respond.

If today's pearl was useful, you'd fit right in at the Functional Medicine Collective! It's a members-only space built specifically for medically-trained clinicians who want peer-level content, not the sensationalist version.

Members get a deep dive like this every Wednesday — recent topics include Lowering Lp(a), best practices for HRT consents, deep dive into using Mastic Gum as a treatment, and what the evidence shows for probiotics that support weight loss — plus a monthly Q&A calls AND access to my quarterly deep dive courses (currently available = ApoB, Leaky Gut, and MCAS).

$99/month, clinician-only, no wellness-speak, no oversimplification... just the literature and how to apply it.

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I hope this was clinically useful!

Meg

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Additional resources that may be helpful:

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