Could probiotics help with weight loss?

Ben Hook BSc (Hons) Nutrition ANutr – Nutritionist

Sadly, weight gain has been rising exponentially for many years, causing both physical and emotional problems for those effected. According to the health survey for England in 2019, since 1993 the proportion of adults in England who are overweight or obese has risen from 52.9% to 64.3%, and the proportion who are obese has risen from 14.9% to 28.0%1. A 2021 global study across 30 countries found that the average weight gain among those who said they had gained weight during the COVID-19 pandemic was 6.1kg2.

This article looks at the role of the gut microbiome in weight management and the best probiotics for weight loss:

Diet ‘fads’ seemingly come and go, with every new diet plan, book or app promising life-changing and sustainable results. But the truth is, that many of these diets fall short of their claims, particularly over the longer term, leading many people to wonder what they are doing wrong.

Feet on scales with measuring tape

Weight loss is a desire for more and more people

Could it be then that there is a missing link, and we have been looking in the wrong places for weight loss strategies? Emerging data indicates that it is possible that the gut microbiome may hold some answers to this elusive weight loss issue.

Evidence has already shown that probiotic bacteria have many beneficial physiological effects, including nutrient assimilation and energy regulation, and this has prompted scientists to expand research into a possible link between gut microbiota and changes in weight (both weight loss and weight gain). In this article we investigate whether taking a simple probiotic supplement could aid in weight loss.

There have been a number of studies exploring the possibility of using probiotics, and in some cases prebiotics, for weight loss. Although current evidence is inconclusive in terms of suggesting a specific probiotic strain, the early research looks promising, and encourages further studies to find out more.

Gut bacteria and weight loss

Possible connections between gut bacteria and weight management are growing. It is already known from earlier studies performed on mice that certain species of bacteria in the gut can cause weight gain, and other species seem to promote weight loss. This was originally shown when researchers transplanted some of the gut microbes from overweight mice to thin mice, and some of the microbes from thin mice to overweight mice. This research3 proved that swapping the microbiota, and therefore changing the gut environment, caused the thin mice to put on weight, and the fat mice to lose weight.

Researchers have also investigated the links between gut bacteria and weight loss in humans. A 2017 Nordic study looked at whether the composition of two groups of bacteria in the participants gut microbiota would influence the outcome of the different weight loss programs. In this case the participants with a higher proportion of Prevotella than Bacteroides lost significantly more weight in 26 weeks when following a New Nordic Diet (NND), high in fibre and wholegrains, than those on the Average Danish Diet8. For the next six months all the participants were instructed to follow the NND diet. Those people with a lower proportion of Prevotella than Bacteroides regained an average of 2.76kg, showing that one type of diet does not fit all!

This isn’t the first investigation into gut bacteria and how easy, or difficult, people find it to lose weight. Back in 2013 a small-scale Mayo Clinic study looked at the gut bacteria of 26 people. Their findings were of great interest, as they discovered that the gut bacteria of those people who found it more difficult to lose weight differed to that of people who were able to lose weight easily5. They identified one specific genus of bacteria, Phascolarctobacterium, to be more closely linked with the ability to lose weight, and a different genus, Dialister, to be associated with the inability to lose weight.

This could be an explanation as to why some people struggle to drop those extra pounds despite dedicating themselves to stringent diets and exercise regimes.

How do probiotics for weight loss work?

Probiotics have been shown to help improve our digestion and absorption of nutrients from our food, so it’s not too surprising to think that different bacteria may help us to extract more calories and nutrients from our food too.

We know that there is a relationship between a person’s diet and the composition of their gut microbiota10. It appears that that the gut senses alterations in nutrient availability and subsequently modulates the nutrient absorption and calorie absorption. A 2011 study found that diets containing 3,400 calories a day significantly affected gut microbiota when compared to more typical 2,400 calories a day diets.

Introducing probiotics into an individual’s daily routine results in a greater diversity of bacteria in the gut. Having a greater diversity of gut bacteria is helpful in many regards, particularly when it comes to losing weight. It has been found that people with less microbiota diversity tend to produce less amino acids when on a weight loss diet than those with a greater microbiota diversity6. Amino acids help the body to metabolise food, therefore we want more! It seems that having a greater diversity of bacteria in the gut, which happens when regularly taking probiotic supplements, maintains levels of amino acids in the body when following a weight loss diet. This keeps the body metabolically active, helping with weight loss and body composition.

Additionally, some Lactobacilli strains have demonstrate the ability to reduce free fatty acid absorption, resulting in reduced body fat and increased weight loss18

Which are the best probiotics for weight loss?

As we know, all strains of probiotics have unique properties and help with different things. When it comes to weight loss it seems that strains within the Lactobacillus genus have more ability to make a difference.

There have been some interesting findings to support the use of Lactobacillus rhamnosus LGG® in modulating excessive weight gain in infants and young children when taken prenatally14. In 2010 study 159 women were randomly assigned to receive either the probiotic L. rhamnosus LGG® or a placebo for 4 weeks before expected delivery until 6 months postnatally. Anthropometric measurements of the children were then taken intermittently from age 3 months up to age 10 in 72% of the children. The perinatal probiotic supplement appeared to moderate the initial phase of excessive weight gain (up to age 48 months), especially among children who later became overweight. Additionally, at age 4 the probiotic supplement group tended to reduce the birth-weight-adjusted mean body mass index.

Healthcare professionals may like to read about further research behind the strain Lactobacillus rhamnosus LGG® on our Probiotics Database: Lactobacillus rhamnosus LGG®

Altering gut bacteria in babies with probiotics may change the growth pattern of the child by controlling excessive weight gain during the first years of life. We would love to see further study in this area.

Two other Lactobacillus probiotic species, Lactobacillus amylovorus and Lactobacillus fermentum, have been associated with a reduction in body fat mass7. In one study a group of 28 overweight individuals consumed yoghurt containing either Lactobacillus amylovorus, Lactobacillus fermentum or no added probiotic (the control group) on a daily basis for six weeks. Participants in the L. amylovorus group reduced their total body fat mass by 4% on average, while those who consumed the yoghurt containing L. fermentum saw a 3% decrease. The control group achieved body fat loss of 1% on average.

Another genus of probiotic bacteria, Bifidobacterium, have also been trialled as a weight loss intervention. Two studies have reported significant reductions in BMI and body fat percentage when participants consumed yoghurts supplemented with multi-strain probiotics, including Bifidobacterium lactis BB-12®, compared with control groups.

A 2014 study used the combination of Lactobacillus acidophilus LA-05, Bifidobacterium lactis BB-12®, and Lactobacillus casei DN001 over an 8-week period. They reported that the overweight and obese individuals who consumed yogurt supplemented with probiotic bacteria in conjunction with a low calorie diet had significantly greater reduction in leptin levels than other participants15.

Another study in 2020 focused on overweight and obese women. The participants undertook 8 weeks on a low calorie diet, either with or without a high protein probiotic yoghurt supplement. The group taking the probiotic yoghurt, supplemented with L. acidophilus LA-05 and B. lactis BB-12®, reported lower BMI and a greater reduction in waist circumference than the control group16.

Optibac Probiotics Bifido & Fibre contains 4g of prebiotic FOS fibers and the probiotic strain Bifidobacterium lactis BB-12®.

Health Professionals can read more about the strains used in this research on our Probiotics Database: Bifidobacterium lactis BB-12® and Lactobacillus acidophilus LA-05

Pouring milk

Taking a probiotic milk drink reduced fat absorption

How long does it take for probiotics for weight loss to work?

It is generally accepted that slow, steady weight loss means the weight is more likely to stay off. There is no quick fix when it comes to weight loss. Therefore, it makes sense that probiotics too are not going to be a quick fix. Changes in gut microbiota can be seen after just a few days of taking probiotic supplements. However, in order for positive changes in the body to take effect it is generally thought that 12 weeks onwards is when most significant changes can be seen. For the best results, a healthy diet and lifestyle goes hand in hand with any probiotic supplementation regime.

Probiotics for menopause weight loss

Interest and research into all aspects of the menopause is rising at a huge rate. And probiotics for menopause and menopause weight loss is no exception.

Menopause occurs in women when periods stop due to reduced hormone levels. You reach menopause when you have not had a period for 12 months. According to the NHS, this usually happens between the ages of 45 and 55 but can be earlier or later for some women. Perimenopause is the time, often over several years, when hormones start to fluctuate before periods cease.

Post menopause it is common for women to notice they have gained weight. Weight gain is often accompanied by a change in body shape, with a tendency towards fat being stored on the stomach rather than hips. It is thought that on average women gain 2-5 pounds during menopausal transition11, and some women are at risk for greater weight gains. Weight gain is partly due to alterations in hormones, while for some women adjustments in lifestyle also contributes.

Some studies suggest that women once they have gone through the menopause tend to have lower gut microbiome diversity compared with pre-menopause12. It seems that menopause is associated with a shift toward greater similarity to the male gut microbiome. Exactly how this impacts weight is still to be established.

Currently, there have been no research studies done on single strain probiotic supplementation for women looking to reduce their weight during perimenopause or post menopause. A 5-week trial using a multispecies probiotic alongside dietary changes showed promising results in lowered BMI13. However, the study did not make it clear which strains were present in the supplement tested, so further research is to be required. As we know, strain specificity is vital when it comes to probiotics.

Exploration into how much of an impact the gut microbiome has on menopause weight gain, and how probiotics can help with weight loss post menopause, is still in its infancy. These are exciting times for women looking to transition smoothly through the menopause years.

Prebiotics for weight loss

We also know that prebiotics such as FOS can help to reduce food intake by making you feel fuller, resulting in a positive knock-on effect on weight loss.

A meta-analysis published in 2012 concluded there is a lack of robust evidence that prebiotics or synbiotics aid weight loss17. Rather than a disappointing result, this seems to have spurred on researchers to conduct further clinical trials. For example, a 2017 study involving 44 overweight children aged 7-12 years found oligofructose-enriched inulin (a type of prebiotic) to significantly reduce body weight and body fat. Analysis also revealed significant increases in species of the Bifidobacterium genus and decreases in Bacteroides vulgatus within the prebiotic group.

Probiotics for bloating

Whilst a reduction in bloating is not precisely the same thing as weight loss, losing inches from their stomach is what most people really want, when they embark on a weight loss regime.

A double-blind, placebo controlled study17 in 2008, followed 41 female study participants, all of whom suffered with IBS-C (IBS with constipation) and complained of abdominal bloating and swelling at least twice per week. The participants were divided in to two groups and given either: a fermented dairy product containing Bifidobacterium lactis DN-173010 or placebo for 4 weeks.

The results showed that the probiotic group saw a significant reduction in both severity of bloating and duration/frequency of the symptom.

Key takeaways

All the clinical research we’ve talked about just goes to show how diverse and incredible our guts really are. It’s clear to see that the studies are mounting to suggest that the bacteria in our gut can have an impact on our weight. So, is it possible that soon we might see a probiotic specific for weight loss?

It is another piece in the jigsaw giving knowledge and power to regain control over our health.

It’s exciting to see how probiotic supplements of the future may help to promote different species of bacteria to grow in the gut that help moderate body weight. There have been positive developments in the use of probiotics in combination with other ingredients, particularly polyphenols and caffeine19, which could pave the way for further evidence for probiotics and weight loss. However, much research is still to be done to identify exactly which species and strains of probiotics are best for weight loss.

  • Our gut and our weight are linked. People who carry extra weight have significantly different microbiomes to those who do not.
  • Research shows that strains of probiotic bacteria within the Lactobacillus genus have most ability to help with weight loss
  • Emerging evidence indicates that prebiotics, alongside probiotic bacteria, may be helpful for people looking to improve their blood lipid profile
  • A more diverse gut microbiome is connected to improved metabolic health markers

For further reading, you might be interested in the following:

Probiotics for sport and fitness

What is dysbiosis?

Health Professionals may also wish to read this related article on our Probiotics Professionals site: Probiotics for obesity 


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