Are Probiotics Helpful for Weight Loss? Here’s What the Science Says

Probiotics are often claimed to be helpful for a range of issues, from colic to allergies to cognitive decline. Recently, research has shown a possible link between probiotics and weight loss. 

So, what does the science say? Is this just hype, or can taking probiotics actually help you manage your weight? Here we’ll review what the evidence shows about the bacteria that live in your gut and why probiotics might help tip the scales when it comes to weight loss.

What are probiotics?

Probiotics are live microorganisms — like bacteria and yeast — that may offer potential health benefits when you consume them. Some foods contain probiotics naturally, while others have probiotics added during the manufacturing process. You can also get probiotics through supplements as pills, powders, or liquids. 

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When you consume probiotics, they join the rest of the microorganisms in your gut (the gut microbiome). In your gut, they may encourage “good” bacteria to grow while also keeping harmful microorganisms under control. Your gut microbiome not only affects how your gut functions but also seems to have health effects beyond your gut. 

Probiotics may benefit your body in many ways, including: 

• Keeping your gut healthy

• Boosting your immune system

• Making essential vitamins and hormones

They’ve also shown promise in preventing or treating many health conditions, like digestive disorders, allergies, and high cholesterol. 

What are prebiotics and synbiotics?

Prebiotics are a type of plant fiber that our bodies can’t digest on their own. But prebiotics can help feed the good bacteria in our gut. 

Some probiotic supplements are mixed with prebiotics. When prebiotics are combined with probiotics, they’re called synbiotics. 

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Can probiotics help you lose weight?

It’s possible. So far, the research on probiotics for weight management has been promising but somewhat mixed. Some studies have found no change in weight with probiotics, while others have found that taking probiotics did indeed help with weight loss. 

A 2023 meta-analysis shed new light on this issue. Researchers looked at over 200 studies on probiotics and/or synbiotics and weight loss. They found that taking probiotics or synbiotics can lead to lower weight, a smaller waist size, and a lower BMI. 

In a 2024 literature review, the authors also found evidence that probiotics lower body weight, waist size, and body fat in people with larger body sizes. 

But the answer might not be so simple. According to the National Institutes for Health (NIH), whether probiotics can help you manage your weight might depend on a lot of things — not just whether or not you’re taking a probiotic. These things include:

• What probiotic strain(s) you’re taking

• The dose of probiotic you’re taking

• How long you take the probiotics

• Your age

• Your biological sex

• Your starting body weight

The truth is: More research is still needed before we can know for sure whether probiotics work for weight management and how exactly to use them. 

What type of probiotic supplements are best for weight loss?

It’s hard to say. When it comes to probiotic supplements, scientists are still researching which strains are most effective for weight loss. 

In clinical trials, probiotic strains that have been found to potentially be effective include: 

• Lactobacillus gasseri (L. gasseri)

• Lactobacillus plantarum (L. plantarum)

• Bifidobacterium species

But even with this information, it can still be hard to choose the “best” supplement. 

Many products use multiple strains of probiotics. And when it comes to dosing, there aren’t clear guidelines for exactly how much you should take. Some studies show that higher doses work better for weight management, but we don’t know if this is true for everyone. 

If you’re interested in taking probiotics, talk to a healthcare professional. They can help you understand which probiotic might be right for you, as well as the potential risks of trying one. 

Which probiotic foods are best for weight loss?

Again, it’s hard to say for sure. But eating foods that contain probiotics is a great way to get health benefits, without the added cost of buying supplements. 

Foods rich in probiotics include:

• Yogurt

• Sauerkraut

• Kimchi

• Pickled vegetables

• Kefir

• Tempeh or miso

If you’re trying to change your body weight, consider eating more probiotic-rich foods. Look for products that list live microorganisms like L. gasseri, L. plantarum, or Bifidobacterium on the ingredients label. 

And remember, other healthy habits can also help you manage your weight. This includes stress reduction, getting good sleep, and exercising. 

How do probiotics affect your weight?

Scientists are still uncovering all the links between gut bacteria and body weight. But so far, there’s evidence that your gut microbiome may affect your weight in several ways:

• Appetite: Some bacteria can produce molecules that affect your brain and make you feel fuller. 

• Fat storage: Some bacteria affect enzymes that encourage your body to store fat. 

• Chronic inflammation: Certain bacteria lead to more inflammation in your body, which is often linked to a higher weight. 

• Circadian rhythm: Some bacteria can mess with your body’s normal circadian rhythm, and an altered circadian rhythm can increase weight. 

• Energy absorption: Certain types of bacteria absorb more calories and fat from the food in your gut.

Probiotics may work to lower weight by influencing these pathways and mimicking the natural good bacteria that line your gut. 

Do people with different weights have a different gut microbiome?

It’s not totally clear. Some of the first insights into the link between weight and probiotics came from studies in mice. Researchers noted that mice who were raised in germ-free environments ate more and gained less than conventionally-raised mice. These germ-free mice had no bacteria in their gut. 

When the germ-free mice were transplanted with bacteria from humans considered “obese”  (BMI over 30), they started gaining more weight. When they were transplanted with bacteria from humans with smaller body sizes, they gained less weight. 

Turns out that humans might also have important differences in the microbiome of people with higher versus lower weight. And it’s possible that your gut health and weight could be linked, at least in part. More research is needed before we can say for sure. 

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Written by:

Karen Hovav, MD, FAAP

Karen Hovav, MD, FAAP, has more than 15 years of experience as an attending pediatrician in a variety of clinical settings. She has worked in a large academic center in an urban city, a small community hospital, a private practice, and an urgent care clinic.

Edited by:

Sophie Vergnaud, MD

Sophie Vergnaud, MD, is the Senior Medical Director for GoodRx Health. An experienced and dedicated pulmonologist and hospitalist, she spent a decade practicing and teaching clinical medicine at academic hospitals throughout London before transitioning to a career in health education and health technology.

Reviewed by:

Sarah Gupta, MD

Sarah Gupta, MD, is a licensed physician with a special interest in mental health, sex and gender, eating disorders, and the human microbiome. She is currently board certified by the American Board of Psychiatry and Neurology.

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