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Probiotics for Weight Loss

Written by Dr. Michael Ruscio, DC on June 27, 2022

Written by Dr. Michael Ruscio, DC on June 27, 2022 — Reviewed by Mike T. Nelson

Here’s What to Know About Probiotics and Your Weight

• Do Probiotics for Weight Loss Work?|
• Support for Probiotics|
• Evidence Against Probiotics|
• The Verdict|
• Probiotic Benefits|
• The Most Effective Ways to Lose Weight|
• The Role of Probiotics in Weight Loss|

As probiotics have gotten more popular they’ve become a bit of a cure-all for health conditions. But while probiotics have many benefits, the trend to use them for weight management needs a more critical look. 

In this article, we’ll discover what is known about probiotics for weight loss. The bottom line is that while there’s a link between gut microbiota and healthy body weight, probiotics are not a magic pill for managing overweight or obesity. 

But since probiotics can balance the microbiome (and the microbiome is linked to metabolic health), they can help support weight loss alongside a healthy diet and exercise regimen.

Let’s get a look into the controversy surrounding probiotics and weight loss.

Do Probiotics for Weight Loss Really Work?

Overall, as we’ll see below, the data suggests that probiotic supplements only have modest effects on actively promoting weight loss. If there is a direct benefit, it tends to be rather insignificant [1, 2]. 

The Link Between Gut Bacteria and Weight 

However, this is not to completely discount the role of gut bacteria in combating obesity. For example, we know there are differences in the microbiota of obese individuals and lean individuals [3]. Lower levels of Bacteroidetes and higher levels of Firmicutes species have been found in obese people, though research is conflicting. It’s not known if being overweight causes bad bacteria to thrive or if bad bacteria drive obesity [1].

Interestingly, having a disrupted microbiome, specifically small intestinal bacterial overgrowth or SIBO, is linked with higher BMI, further hinting at the relationship between the microbiome and overall weight.

Two studies have shown a relationship between SIBO and body weight. In these studies, patients who tested positive for SIBO had higher BMI scores than patients without SIBO [4, 5]. However, not all the data show that SIBO correlates to weight gain, so the exact relationship between dysbiosis and increased BMI is unclear [6].

One theory is that hydrogen sulfide-producing bacteria work against your weight loss attempts by causing you to absorb extra calories from your diet [7, 8].

The research isn’t perfect, but it does illustrate that the microbiome is tied to metabolic health. As probiotics are excellent in restoring the gut flora, it’s reasonable to assume that they can also have an effect on overall weight — let’s see what the research says.

Studies That Support Probiotics for Weight Loss

The following studies are often cited as evidence that probiotic supplements are useful for weight loss:

• A small study involving 28 overweight participants found that those given yogurt containing Lactobacillus amylovorus lost 3% body fat. Those consuming yogurt containing Lactobacillus fermentum lost 4% body fat. A control group that wasn’t given probiotics lost only 1% body fat [9].
• A study published in the British Journal of Nutrition showed that women who took Lactobacillus rhamnosus supplements while on a weight control diet lost around 4 lbs more on average over 12 weeks than compared to those who just dieted but didn’t take probiotics. The probiotics offered no enhanced weight or fat loss benefits in men [10].
• A group of ​​210 healthy Japanese adults with excess visceral fat (fat wrapped around the organs) had an 8.5% decrease in this fat when they consumed fermented milk containing Lactobacillus gasseri [11].

Studies That Don’t Support Probiotics For Weight Loss

However, other research doesn’t support a strong link between probiotics and weight loss. For example:

• A 2021 systematic review and meta-analysis involving over 1700 overweight and obese participants determined that taking single and multi-species probiotics resulted in just 1.5 pounds of weight loss and less than half an inch lost off the waist [12].
• A separate 2021 systematic review and meta-analysis which compared the effects of probiotics versus placebo in overweight or obese people found probiotics were linked with less than ¾ of a point reduction in Body Mass Index (BMI) [13].
• A systematic review of over 27 randomized controlled trials concluded that good bacteria (largely Lactobacillus and Bifidobacterium strains), could help reduce weight and body fat mass in overweight and obese populations. However, many of the studies included multiple weight loss strategies, so probiotics probably weren’t the main factor [14].
• In a systematic review evaluating whether probiotics are effective for managing overweight and obesity, half of the studies seemed to show some benefit, while the other half did not. However, microbial composition changes were reported as outcomes only in 3 studies, and the authors state that “due to the limited number of studies included, the effects of probiotics treatments in the prevention and treatment of overweight and obesity still need more consistent work” [15].
• A 2019 meta-analysis of 19 clinical trials suggested that probiotic supplements have a small effect on reducing waist circumference but no effect on body weight or BMI [16].

A 2017 systematic review evaluated the effects of Lactobacilli on weight loss and/or fat mass in overweight adults. Of 14 studies included in the review, nine showed decreased body weight and/or body fat, three did not find effect and two showed weight gain [17].

Probiotics For Weight Loss: Verdict

You’ll notice that the studies that didn’t find much of a weight loss benefit for probiotics, or had mixed findings, are more numerous than those that do. Additionally, they are all meta-analyses and systematic reviews, meaning that they analyze many studies in one go and give us access to much better quality data and more insights. 

By comparison, the studies that support probiotics being used to lose weight tend to be smaller and less robust. They are often seized by internet marketers looking to cherry-pick data that will support their marketing goals.

This highlights the need to use caution before putting too much clout into weight loss trends. However, this doesn’t mean we should cast aside the use of probiotics for weight loss completely. While probiotics may not instigate weight loss directly, this doesn’t mean they can’t be part of the overall picture when it comes to losing weight. 

Beneficial bacteria can be used alongside a healthy diet and regular exercise routine as they shine in healing the gut, which can indirectly (and positively) impact your ability to maintain a healthy weight. Let’s hone in a bit more on what probiotics can do for your digestive health, metabolic health, and overall well-being.

Probiotics Provide Gut Health and Other Body Benefits

While they probably aren’t the most effective first-line treatment for weight loss [16, 18], the healthy bacteria in probiotics do help to restore gut health, which leads to better metabolic and overall health. Health benefits of probiotic supplements include:

• Balancing the good microbes and bad bacteria in your gut microbiome [18].
• Boosting the immune system (which is primarily located in your digestive tract) [19, 20, 21].
• Reducing the inflammation in the digestive tract and elsewhere in the body [22].
• Improving digestive health conditions like IBS, Crohn’s disease, and colitis [22, 23, 24, 25].
• Reducing gut symptoms like bloating, diarrhea, and constipation [26, 27, 28, 29, 30].
• Helping with many non-digestive symptoms like anxiety, vaginosis, gum disease, and even heart disease [31, 32, 33, 34, 35, 36].
• Improving glucose control and insulin resistance in those with type 2 diabetes [37].
• Normalizing cholesterol and other lipid levels [38, 39, 40, 41, 42].

The research shows that probiotics have numerous health benefits, including better blood sugar control and improved lipid levels, which can affect weight. One of the extended benefits patients often experience after alleviating gut health issues with probiotics is that they feel generally better and have more robust energy levels and improved mental health. This in turn can help people tackle their excess weight more successfully. 

So while the key diet and exercise strategies below are the most important ones to tackle to lose weight, a more comprehensive strategy is also to improve your gut health, with probiotics being one part of that.

Which Probiotic Is Best to Support Weight Loss?

With so many thousands of probiotic strains and considerable differences in gut flora across populations of people, the “best” type and ratio of bacteria for staying slim is hard to define. There isn’t necessarily a specific probiotic strain that is best for improving your metabolic health, but rather using a variety of different strains of bacteria is probably best to cover all bases.

The best probiotic supplement to support a healthy diet and weight loss regimen is likely to be one that contains multiple species, for example, a combination of Lactobacillus / Bifidobacteria strains, soil-based probiotics, and beneficial yeasts. It can be challenging to find a supplement that contains all of these types of probiotics, so taking them separately is often more reasonable.

The Most Effective Ways to Lose Weight

To lose weight, you will need to take in less energy than you expend, but ironically calorie counting rarely works. Focusing on nutrient-packed foods that will make you feel satiated and full is a much better idea, and is supported by research [43].

It’s a good idea to ensure your diet includes the phytochemicals, good fats, fermented foods (e.g.kimchi and kefir), and prebiotic fibers needed to help a wide variety of good bacteria flourish. Some eating plans that have shown promise in helping people lose weight include: 

Meal replacements: One systematic review/meta-analysis found that calorie restriction with meal replacements was more effective for weight loss than standard calorie restriction. Meal replacement plans include bars and shakes (such as Elemental Heal) that are fortified with all the nutrients you need and designed to replace 1 to 3 meals per day. Diets that included at least 60% of calories from meal replacement had the greatest effect on weight loss [44].

Intermittent fasting: A 2021 systematic review/meta-analysis showed that periodic rather than continuous calorie restriction, e.g. for 2–3 days each week, may have the greatest effect on weight loss [45]. One review that looked at five different diets  including the Mediterranean diet, a low-fat diet, and calorie restriction found that all led to significant weight loss in patients with both type-1 and type-2 diabetes. However, maintenance of weight loss only occurred when fasting or intermittent fasting was present [46].

Keto diet: A review of several low-carb diets found that following a very low calorie ketogenic diet for at least a month could lead to dramatic weight loss (22 lbs to 34.4 lbs in 4 weeks) [47]. This weight loss was stable for up to 2 years and cholesterol levels, triglycerides, and liver enzymes also improved.

For people who need to lose a lot of weight fast for medical reasons, a keto diet is certainly very effective, but in my clinical experience it can cut carbs too drastically and affect your energy levels. If you don’t have to lose weight very rapidly, a Paleo-style diet works better for most of my patients and is where I advise most people who want to both manage their weight and look after their gut health to start.

Exercise for Weight Loss

Physical activity is generally more effective for helping to maintain a healthy body weight and less effective for actual weight loss [48]. That said, HIIT (high-intensity interval training) has the biggest chance of being effective for trimming down and is definitely more effective than probiotics for weight loss.

• One study found that HIIT training done 3 times a week for 8 weeks or more led to mild reductions in body weight and total belly fat mass in premenopausal women [49].
• HIIT 2-3 times a week for 6-12 weeks reduced body weight by an average of 3.8 lbs, while also reducing body fat percentage, and waist size, in obese teenagers [50].
• HIIT and progressive resistance training (PRT), alone or in combination, also reduced BMI and body fat percentage in older adults with a high risk for diabetes or heart disease [51].

The Role of Probiotics in Weight Loss

While there are lots of great reasons to take probiotics, significantly reducing weight and body fat doesn’t seem to be one of them. The main role of probiotics is to look after your gut health and digestive system by tipping the balance in favor of a healthier microbiota. 

One side benefit of probiotics may be helping to create the right environment for maintaining a healthy weight and improving metabolic health, but they probably don’t directly help burn calories. To sum it up, you shouldn’t solely rely on probiotics for weight loss, but they can certainly be part of a comprehensive weight loss plan.

Rather than only focusing on probiotics for weight loss, you should think about eating a healthy, unprocessed diet to lose the pounds, such as the Paleo diet. To speed up your efforts, you can also try calorie restriction through meal replacement shakes or intermittent fasting. Lastly, don’t forget to throw in some physical activity to help maintain your weight loss efforts.

For more help with gut health or weight issues, reach out to the Ruscio Institute for Functional Medicine.

The Ruscio Institute has developed a range of high-quality formulations to help our patients and audience. If you’re interested in learning more about these products, please click here. Note that there are many other options available, and we encourage you to research which products may be right for you.