Articles

Evidence based

Evidence Based

This article is based on scientific evidence, written by experts and fact checked by experts.

Our team of licensed nutritionists and dietitians strive to be objective, unbiased, honest and to present both sides of the argument.

This article contains scientific references. The numbers in the parentheses (1, 2, 3) are clickable links to peer-reviewed scientific papers.

Probiotics for Weight Loss

Written by Dr. Michael Ruscio, DC on June 19, 2025

Written by Dr. Michael Ruscio, DC on June 19, 2025 — Reviewed by Hilary Watts

• Do Probiotics for Weight Loss Work?|
• Research|
• The Verdict|
• Probiotic Benefits|
• Best Ways to Lose Weight|

Probiotics promise better digestion and clearer skin, but can a daily capsule really shift the scale? 

In this article, we’ll explore what the research really says about probiotics and weight loss. While there is a connection between gut microbiota and healthy body weight, probiotics aren’t a magic solution for managing overweight or obesity. 

That said, certain strains—like Lactobacillus gasseri and Bifidobacterium species—have shown promise in supporting modest weight loss, especially in individuals with excess weight.

Because 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 take a look at the controversy surrounding probiotics and weight loss.

Do Probiotics for Weight Loss Really Work?

Data suggests that probiotic supplements only have modest effects for weight loss. If there is a direct benefit, it may be fairly insignificant. 

The Link Between Gut Bacteria and Weight 

However, gut bacteria do play a role in obesity. For example, there may be differences in the microbiota of obese individuals and lean individuals 1. Lower levels of Bacteroidetes and higher levels of Firmicutes species have been found in obese people, though research is conflicting 2. It’s not known whether being overweight may cause bad bacteria to thrive or if bad bacteria may drive obesity—it could even be some combination of the two 3.

Interestingly, having dysbiosis, or a disrupted microbiome—specifically a small intestinal bacterial overgrowth (SIBO)—is linked with higher body mass index (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 with SIBO had higher BMI scores than patients without SIBO 4 5. However, not all the data show that SIBO correlates with weight gain, so the exact relationship between dysbiosis and increased BMI is unclear 6.

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

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 may also have an effect on overall weight.

Research on Probiotics for Weight Loss

Two meta-analyses (studies of studies) that together evaluated 208 randomized controlled trials (gold-standard experiments) on how probiotics affect weight loss have found that probiotics can have modest but consistent benefits 8 9. Taking probiotics or synbiotics (probiotics plus prebiotics) can lead to small but statistically significant reductions in weight and fat-related measures. For example, after taking probiotics for 2–6 months, the average changes included:

• People lost about 2 pounds of total body weight, all of which was fat, dropping their body fat percentage by 0.68%.
• Body size slightly decreased—BMI went down by 0.28 points, and waist size shrank by almost half an inch.
• Fat distribution improved slightly—waist to hip ratio dropped by 0.01, suggesting a small shift away from abdominal fat.

A bonus finding is that probiotics and synbiotics did not change fat-free mass or lean body mass, suggesting they can reduce fat without affecting muscle.

People saw benefits whether they took probiotics or synbiotics as food or supplements, but only probiotics (not synbiotics) showed significant fat loss in subgroup analysis.

These findings align with broader evidence that probiotics can support better metabolic health, including modest improvements in body composition. Though the weight loss is not dramatic, probiotics may serve as a useful addition to diet, exercise, or medication in managing weight and belly fat.

The Verdict on Weight Loss Probiotics

The very modest improvements in weight loss that those powerful studies showed highlight the need to use caution before putting too much trust into weight loss trends. However, this doesn’t mean we should cast aside the use of probiotics in weight loss completely. 

Probiotics may not instigate weight loss directly, but this doesn’t mean they shouldn’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. Together, these shine at 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, the healthy bacteria in probiotics do help to restore gut health. 

Better gut health can lead to better metabolic functioning—the way your body handles blood sugar, cholesterol, blood pressure, and weight—and overall health. According to high-quality research, the many health benefits of probiotic supplements may include:

• Balancing the good microbes and bad bacteria in your gut microbiome 10
• Fighting off harmful microbes and their toxins 11 12
• Boosting the immune system (which is primarily located in your digestive tract) 13
• Reducing the inflammation in the digestive tract and elsewhere in the body 14
• Supporting microbiome recovery from gut imbalances 15
• Repairing your gut lining (reducing leaky gut) 16
• Reducing anxiety and depression 17
• Clearing acne 18
• Preventing bacterial vaginosis 19
• Improving nutrient deficiencies 20
• Reducing lactose intolerance 21
• Improving metabolic health in polycystic ovary syndrome (PCOS) 22
• Reducing a common pregnancy infection called Group B streptococcus 23
• Reducing the disease activity of rheumatoid arthritis 24
• Easing seasonal allergies 25

As you can see, research shows that probiotics can have numerous health benefits, including better blood sugar control and improved cholesterol levels, which can affect weight 26.

In the clinic, it’s common for our clients to feel better and have more energy and a better outlook on life after taking probiotics to heal their gut issues. This kind of response often helps people tackle their excess weight more successfully. 

Which Probiotic Is Best to Support Weight Loss?

With many thousands of probiotic strains and the 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 weight and metabolic health—instead, 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 and Bifidobacterium strains, soil-based probiotics, and beneficial yeasts. It used to be challenging to find a supplement that contained all of these types of probiotics, so we formulated one: Triple Therapy Probiotic Powder Sticks. 

The Most Effective Ways to Lose Weight

To lose weight, you need to burn more calories than you take in, but calorie counting isn’t always necessary for successful weight loss—and sometimes it can create more stress than good. A better strategy is to focus on nutrient-dense, filling foods that support gut health, along with lifestyle changes such as getting regular exercise.

Research supports several effective eating plans:

• Meal replacements, such as shakes fortified with vitamins, minerals, and nutrients, can be more effective than standard calorie restriction, especially when at least 60% of calories come from meal replacements 27.
• Intermittent fasting can lead to similar weight loss as daily restriction 28. 
• A Mediterranean diet can improve weight loss and keep it off sustainably 29.  
• The keto diet, also known as the ketogenic diet, can lead to impressive weight loss 30, although this high-fat, low-carb eating style can be difficult to maintain long-term.
• A Paleo diet can be an effective and sustainable choice for shifting the scale and improving blood sugar regulation and metabolic health 31 32. 

Exercise plays a bigger role in weight maintenance, but high-intensity interval training (HIIT) has shown the most potential for weight loss. It’s been linked to reductions in body fat, waist size, and BMI across several groups, including older adults 33, kids and teens 34, and women 35. However, any movement is better than none, and the best exercise is the kind you can sustain. 

Want help finding the right weight loss approach for your body and goals? Schedule a consultation with our virtual clinic today.

The Role of Probiotics in Weight Loss

While probiotics play an important role in supporting gut health, research suggests they aren’t a strong tool for losing weight. Their main benefit lies in improving the balance of your gut microbiota, which can support metabolic health and help with weight maintenance, but they likely won’t lead to significant weight loss on their own.

That said, certain strains of probiotics may offer modest support for weight loss—particularly in individuals with overweight or obesity—when combined with other healthy habits.

Rather than relying on probiotics alone, the best approach is to include them as part of a comprehensive plan that also features a nutrient-dense diet, healthy calorie-restricting strategies, and regular physical activity to help sustain results.

Start supporting your microbiome today: Shop Dr. Ruscio’s Probiotics.

The Ruscio Institute has developed a range of high-quality formulations to help our clients 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. The information on DrRuscio.com is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment.