April 7, 2020/Digestive

Could Probiotics Help With Weight Loss?

Researchers are learning more about the link between weight and gut bacteria

Probiotics in digestive track of woman

In the quest for a weight loss magic bullet, some Americans have turned their attention to probiotics. Some believe that probiotic supplements — which support the friendly bacteria that naturally live in the gut — can help them shed extra pounds.


Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy

Are probiotics the weight loss tool we’ve been waiting for? Gail Cresci, PhD, RD, a researcher and expert on the gut microbiome, explains.

How it all started

Years ago, scientists discovered that the makeup of friendly gut bacteria (known as the gut microbiota) was different in people who have obesity than in people with an average weight.

To learn more, researchers implanted friendly gut bacteria from the different types of people into special mice without gut bacteria and found:

  • No weight change when the mice received gut bacteria from people of average weight.
  • Weight gain when the gut bacteria was from a person with obesity.

Given these findings, it seemed possible that gut bacteria play a role in regulating weight.

In humans, the only comparison researchers have to the mice study is with gut microbiota transplants (known as fecal transplants), Dr. Cresci says. Doctors perform fecal transplants for people who have an overgrowth of bad pathogenic gut bacteria called Clostridioides difficile. They place stool from a healthy person into the colon of the person with C. diff.

“Researchers are finding that many naturally thin patients who receive a fecal transplant become overweight over time,” Dr. Cresci says. “Since 40% of Americans have obesity, it’s likely that 40% of the gut microbiota transplants came from a person with obesity, possibly causing this unexpected weight gain.”

Is probiotic-induced weight loss a myth?

These findings created hope and hype that simply popping a pill with the right gut microbiota could be the key to weight loss.

“The problem with this logic is that fecal transfers include trillions of diverse microbes that include bacteria, viruses, fungi and yeasts,” Dr. Cresci says. “With a probiotic, it’s likely a person could only receive a fraction of that, with one to just a few beneficial microbes so there’s no guarantee it will affect weight loss.”

And even newer research looking at synbiotics (the combination of a probiotic and prebiotic) found they didn’t affect weight loss or body composition. It wasn’t a total buzzkill, though: Synbiotics did positively impact the composition of friendly gut bacteria.

“I think it’s safe to say that the available probiotics probably won’t help people lose much, if any, weight,” says Dr. Cresci. “But researchers continue to explore the link between weight and gut bacteria — there’s still potential.”

The right diet may improve your gut microbiota … and your health

Probiotics’ main claim to fame is enhancing your good bacteria and keeping you in tip-top health. Even if a supplement won’t cause the weight to fall off, should you take one anyway for your gut health?


What researchers do know is this: Healthy diet first, supplement second. A balance of healthy sources of proteins, fats and carbohydrates is the most important factor in maintaining good gut bacteria. The friendly bacteria survive and thrive when fed high-fiber foods.

A low-fiber diet (low-carb and high-protein and/or high-fat), though, reduces the number of good bacteria.

“Since a low-carb diet doesn’t offer enough nutrition for the good bacteria, the gut microbiota blend shifts, and the beneficial ones get depleted. The bad bacteria then begin to take over,” says Dr. Cresci.

In one study, researchers found that the bad bacteria consumed the protein and produced byproducts linked to higher rates of colon cancer.

So while the jury is still out on whether probiotics can lead to weight loss, it’s clear, once again, that a healthy diet is key. A high-fiber diet can help you maintain gut — and overall — health. For some people, a probiotic could work alongside a nutritious diet to shore up gut health. Talk to your doctor to see if it’s right for you.


Learn more about our editorial process.

Related Articles

Juiced fruits and veggies dispensing from a juicer on counter in kitchen
April 24, 2024/Weight Loss
What You Need To Know About Juicing for Weight Loss

Juicing cleanses don’t target fat loss — and you’ll lose important nutrients in the process

Spoonful of apple cider vinegar
March 27, 2024/Weight Loss
Does Apple Cider Vinegar Help You Lose Weight?

The science on ACV isn’t very promising for weight loss or appetite suppression

Female struggling to push a large rock up a hill
March 21, 2024/Weight Loss
Why It Really Is Harder for Women To Lose Weight (and What To Do About It)

Genetics, metabolism and hormonal fluctuations can all make weight loss more difficult

female sitting meditating, eyes closed
March 19, 2024/Weight Loss
14 Ways To Lose Belly Fat

Losing belly fat can reduce your risk for chronic health conditions — try focusing on a diet high in lean protein, exercising regularly, reducing stress and getting quality ZZZs

Powdered greens in a container, with powdered green smoothies and blueberries
March 11, 2024/Nutrition
Powdered Greens: Do They Really Work?

The supplement shouldn’t replace a healthy diet, but it can help you get in your fruits and veggies

Person eating healthy bowl of noodles with fitness items floating around head
January 17, 2024/Weight Loss
How To Shed 10 Pounds — For Good!

Actively choose healthy habits not only when it comes to food and nutrition, but also physical activity and your mental health

Carbohydrate food including oats, fruits and nuts all combined into a healthy breakfast.
November 20, 2023/Nutrition
Pros and Cons of a High-Carb Diet: Can You Lose Weight?

It’s all about choosing complex carbs — like whole grains — that will keep you full

clock with diet foods and water
November 14, 2023/Weight Loss
The 10 Worst Ways To Lose Weight

Trying fad diets and skipping meals won’t do you any favors

Trending Topics

Person in yellow tshirt and blue jeans relaxing on green couch in living room reading texts on their phone.
Here’s How Many Calories You Naturally Burn in a Day

Your metabolism may torch 1,300 to 2,000 calories daily with no activity

woman snacking on raisins and nuts
52 Foods High In Iron

Pump up your iron intake with foods like tuna, tofu and turkey