Probiotics for Weight Loss: How Your Gut Bacteria Affects Your Weight

August 27, 2021
Weight Loss

What you weigh can be influenced by much more than what you eat and how much you move. 

Did you know you have a gut-brain connection where the bacteria in your gut can improve or impair your energy metabolism? The bugs in your belly can either signal to your brain that you’re satisfied and not hungry or they can whisper that you need a heaping order of nachos before your taco trio entree. 

The bacteria that make up your gut microbiota can pull all sorts of appetite and fat-burning strings that can impact your weight loss efforts. Probiotics, live bacteria or yeast that hang out in your gut, are “good” bugs that work to keep you healthy and at a manageable weight.

Is there a connection between probiotics and weight loss? Possibly, but be forewarned that weight loss from a pill and nothing else remains a pipe dream. Science might get there someday, but for now, probiotics aren’t that magic weight loss pill. 

Quick Primer on Probiotics

Probiotics, live mircroorganisms found in yogurt, supplements, and fermented foods, are beneficial bacteria ingested to improve balance in your gut microbiota. Astonishingly, your gut hosts trillions of microorganisms from more than 500 different species. Probiotics consist of Saccharomyces boulardii yeast or lactic acid bacteria, such as Lactobacillus and Bifidobacterium species. 

Probiotics may help:

Probiotic dosage is expressed in CFU, or colony-forming units. The number of CFUs relates to the number of live strains in each dose; some probiotic pills contain millions of CFUs and others hundreds of billions. The type of strain, product formula, quality, and dose you choose will depend on your purpose for taking it. Discuss any dosage and duration questions with your doctor before you start supplementation.

Probiotics for Weight Loss: Do They Actually Work?

Sorry to burst your probiotic bubble, but scientific research remains mixed on whether probiotics can directly assist with weight loss. Let’s comb through some of the research highlights.

A meta-analysis review from 2015 concluded that probiotics are not effective for weight loss6 or decreasing body mass index (BMI).

A 2020 study conducted on obese women with food addiction found that multi-probiotic supplementation significantly reduced body weight7, BMI, waist circumference, body fat percentage, and belly fat compared to the placebo group. Researchers noted a significant improvement in eating behaviors in the group given probiotics as well as a dip in leptin (a hormone that decreases your appetite) compared to baseline values. 

There could be indirect influences from probiotic, prebiotic, and synbiotic (combination of probiotics and prebiotics) supplementation that affect the secretion of hormones and neurotransmitters that impact the food intake triggers that lead to weight gain8. 

Again, no consensus exists; one systematic review of 24 studies found that probiotics have minimal effects on appetite-related hormones9 in overweight people. Another review noted “significant but small effects” on body weight10 (less than 3%), but highlighted decreased fasting and post-meal glucose levels as well as improved insulin sensitivity in those taking probiotics. Importantly, researchers point out that these effects were seen in those who ate multiple-strain fermented milk or yogurt products for at least two months, versus popping probiotic pills.  

Research on probiotics therapy for obesity11 is gaining momentum. Scientific evidence suggests that gut microbiota can alter body weight12 by affecting energy balance. As an example, one study on 20 non-obese, healthy men showed that probiotic (VSL #3) supplementation provided some protection from fat accumulation and weight gain13 in men who ate a high-fat, high-calorie diet.  

Will probiotics help you lose weight? Research isn’t definitive, but trials do suggest a beneficial impact on insulin sensitivity and metabolism. 

Probiotics for Weight Loss: What to Take 

Curious about whether to add probiotics to your weight loss routine? Experiment to see if boosting your probiotic intake makes an impact. Consult with your doctor, but little known side effects exist from taking probiotics, except for possible gas, bloating, and tummy aches if you take too much. 

A multi-strain probiotic supplement and adding foods high in probiotics and prebiotics can benefit your belly—not just its size but also its health.

Probiotics for Weight Loss on a High-Fat Diet

If you jumped on the keto bandwagon to lose weight or are a die-hard low-carb diet fan, you may have read that some animal studies link a high-fat diet to changes in the gut microbiota that may encourage weight gain. One such study in rats suggested that a high-fat, high-calorie diet led to inflammation in the gut that impaired food intake regulation and possibly triggered excessive eating and obesity14. 

If you love cooking with olive or avocado oil, snacking on nuts, eating cold-water fatty fish, and adding sliced avocado to just about everything, no need to stop just because you want to lose weight (just keep your portions reasonable). One study (on humans) showed promise in triple viable probiotics supplementation for those on a high-fat diet15—the probiotics expanded the phyla of beneficial gut bugs and reduced the bad ones.  

Don’t Come up Short on SCFAs: How to Hack Your Appetite

The gut microbiota plays a role in energy metabolism through the production of short-chain fatty acids (SCFAs), made by your gut bugs from the breakdown of fiber and protein. Acetate, propionate, and butyrate are SCFAs that can impact insulin sensitivity, glucose balance, and body weight—specifically by regulating satiety and reducing appetite16. One study highlights the effects of taking butyrate: It activates the gut-brain neural connection to reduce calorie intake and rev up fat burning17.

How can you reap the potential weight-impacting benefits of acetate, propionate, and butyrate? Eat more foods made from fermented bacteria18, such as:

  • Cheese
  • Butter
  • Yogurt
  • Pickles
  • Sauerkraut
  • Kimchi
  • Soy sauce and other fermented sauces
  • Legumes
  • Intact whole grains (not ground into flour)

Remember the modest weight loss results from this study? Researchers recommend taking fermented milk and yogurt products for the most potential benefits to your body weight.

Try adding plain kefir, plain yogurt with live and active cultures—if you can’t tolerate or don’t enjoy dairy, try dairy-free cashew kefir or probiotic coconut yogurt—to your diet for at least two months to see if you notice any difference. 

Just watch the amount of sugar added to these products to make them yummy. For example, one cup of strawberry kefir19 contains 20 grams of sugar total and 8 grams of added sugar. One cup of plain kefir20 has 12 grams of sugar total (from milk) and 0 grams of added sugar. It might take a minute to get used to the tart, tangy flavor of plain dairy and dairy alternatives, but these lower glycemic options are better for your metabolic health. 

This quick list summarizes the probiotic supplements and foods that may help your weight-loss efforts:

  • Triple viable probiotics (supplement)
  • Fermented milk products like kefir, yogurt, cheese
  • Non-dairy fermented foods like soy sauce, sauerkraut, pickles, vinegar, certain whole grains, and legumes
  • Non-dairy, plant-based fermented products like probiotic coconut yogurt or cashew kefir

Make sure to read our epic list of prebiotic foods to reap the synbiotic benefits of adding prebiotics and probiotics to your diet. 


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