Probiotics seem to be the go-to solution for SO many health problems these days, but can probiotics really help you reach your weight loss goals too?

These live microorganisms have a variety of legit health benefits (like doing your immune system, digestion, and heart health a solid). There’s also a decent amount of research to suggest that certain types of probiotics may help you lose weight.

But the wrong strain of probiotics may actually do the opposite and cause weight gain. Here’s the deal with probiotics and weight loss.

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Even if you’re not a kombucha or kefir stan, you’ve prob had a healthy dose of probiotics in the likes of yogurt, pickles, or other fermented foods.

Your gut is filled with hundreds of microorganisms as it is — most of them friendly little guys that produce important nutrients like vitamin K and B vitamins. They also help break down fiber that your body can’t digest.

When you add some more microorganisms to the mix with help from probiotics, it’s really a party. Here’s how that might help with weight loss.

May support body weight regulation

Research shows there’s likely a correlation between gut bacteria and regulating body weight.

Basically, there are two main fams of “good” gut bacteria: Bacteroidetes and Firmicutes. Experts believe body weight is related to the balance of these two types.

Human and animal research (including publications from 2020, 2019, and 2016) indicates that people and critters with moderate body weight tend to have different gut bacteria than those who are overweight or have obesity.

In most studies, folks with obesity had more Firmicutes and fewer Bacteroidetes than people with moderate body weight. But a 2020 review of several studies found no correlation between bacteria ratios and obesity at all. 🤯

Reduces appetite and fat absorption

TBH, the connection among probiotics, body fat, and weight isn’t totally understood yet. But science has some theories.

According to research from 2018 and 2019, probiotics may affect fatty acid function and suppress appetite.

Research from 2020 also supports this idea. Basically, probiotics may promote the release of appetite-suppressing hormones like peptide YY. If you have higher levels of these hormones, you may be able to burn calories and fat more easily.

Researchers in a 2015 test-tube study proposed that certain probiotics may also limit fat absorption from food and boost the amount of fat that *ahem* exits through your body.

Bacteria strains such as those in the Lactobacillus fam seem to work this way, in particular.

Reduces risk of inflammation and obesity

According to a 2020 research review, taking probiotics may lower obesity risk by boosting levels of fat-regulating proteins. Increased levels of proteins (hello, angiopoietin-like protein 4!) may cause your body to store less fat.

Obesity is also strongly linked to inflammation. And research suggests that, by improving the health of the gut lining, probiotics may reduce inflammation and reduce your risk of developing obesity and other health conditions.

Because inflammation is also linked to issues like constipation, diarrhea, and inflammatory bowel disease, probiotics are also thought to aid in healthy digestion.

It turns out probiotics are as varied as our own families — eccentric aunts included. Here’s the deal with picking the right probiotic strain to help your weight loss goals.


So far, Lactobacillus family strains seem to be the MVPs of weight loss. In a 2018 review of several studies on Lactobacillus strain supplementation, researchers found a notable reduction in body weight, BMI, and fat percentage in participants.

Effective types include:

  • Lactobacillus gasseri
  • Lactobacillus amylovorus
  • Lactobacillus fermentum
  • Lactobacillus sakei

In a small 2020 study in 114 adults with obesity, those who took the supplement Lactobacillus sakei for 12 weeks experienced significant reductions in body fat mass and waist size compared with a those who took a placebo.

There’s also loads of evidence to suggest Lactobacillus gasseri has a major impact on weight loss, including studies from 2010, 2013, and 2015.


Though there’s less research so far on Bifidobacterium strains, they also seem to be pretty legit for weight loss. Potential winning weight loss strains include:

  • Bifidobacterium animalis subsp. lactis
  • Bifidobacterium bifidum

In a small 2019 study in 135 people, those who took Bifidobacterium animalis subsp. lactis daily for 3 months lost a lot more belly fat, inches off their waist, and numbers off their BMI than the placebo group.

In a small 2017 study, women who were overweight or had obesity dieted and took either a probiotic (containing both Lactobous lactis and Bifidobacterium bifidum) or a placebo. Those who took the probiotic lost significantly more belly fat than the placebo group.


The strain VSL#3 may help prevent weight gain, even when you’re consuming lots of cals. (Pass the mac and cheese, please!)

In a small 2015 study in 20 men with BMIs of less than 30, the participants who took the probiotic formulation VSL#3 while on a super high fat diet had less weight gain and fat gain than the placebo group.

Still, we need more research before we can say this strain truly helps weight loss.

Remember when Cady tricked Regina into eating “weight loss” bars that actually packed on the pounds? Yeah, turns out probiotics can also pull this unwanted switcharoo — even without the help of any mean girls.

A 2016 review of several studies found that probiotics’ effects on body weight depend on the species and strains — even within the same family. For instance, Lactobacillus gasseri BNR17 reduced weight gain compared with controls, while Lactobacillus gasseri L66-5 *promoted* weight gain.

Sound confusing? Well, it is. For now, the reason behind this slight variation in strains is still a mystery.

Although more research is needed, potential weight gain-promoting strains include:

There’s a lot of research to support the idea that probiotics can help with weight loss. Studies show that strains in the Lactobacillus gasseri, Bifidobacterium, and VSL#3 families may be particularly effective for weight management.

Keep in mind that certain strains, like Lactobacillus gasseri L66-5, have been found to actually cause weight gain. But more research is needed before we can understand why and how this happens.

Even if you’re not looking to lose weight, eating probiotic foods is generally great for digestive health.