Can Probiotics Really Help You Lose Weight?
If you’ve spent any time looking for ways to make weight loss easier, you’ve probably come across probiotics. They seem to be everywhere now, particularly alongside all the discussion about gut health, and it’s very easy to come away with the impression that getting the right bacteria into your gut could somehow make the weight start falling off.
I can understand why that’s appealing. Having struggled with my weight for much of my adult life, lost more than 10 stone and subsequently explored everything from Slimming World to weight-loss medication and the bariatric surgery pathway, I’ve become very familiar with the endless stream of things that supposedly make weight loss easier.
Some turn out to have good evidence behind them, while others have a tiny bit of promising research that gets transformed into a much bigger claim by the time somebody is trying to sell you a supplement.
Probiotics sit somewhere in the middle of that.
There is genuine scientific interest in the relationship between our gut microbiome and obesity, and researchers have found some potentially interesting effects from particular probiotics. What we don’t currently have is convincing evidence that taking a probiotic supplement will result in meaningful weight loss for most people.
So, before you spend £20 on a bottle because the packaging mentions metabolism, gut health or weight management, let’s look at what we actually know.
What Are Probiotics?
Probiotics are live microorganisms, usually bacteria or yeasts, that are found in some foods and supplements. You might have heard them described as “friendly” or “good” bacteria because they are often marketed as helping to support the balance of microorganisms living in our gut.
The NHS says there is evidence that probiotics may be useful in some circumstances, including helping some people with symptoms of IBS, but it is much more cautious about many of the wider health claims surrounding them.
One of the difficulties is that “probiotic” isn’t one single thing.
There are numerous different species and strains, and something demonstrated in a study using one particular strain at a particular dose can’t automatically be applied to every probiotic yoghurt or supplement on the supermarket shelf.
This becomes especially important when we start talking about weight loss because it’s very easy to read that researchers have studied Lactobacillus or Bifidobacterium and assume that buying anything containing those words will have the same effect.
Unfortunately, nutrition research is rarely quite that convenient. Check NHS guidance too for more about the safety of probiotics.
Why are probiotics being studied for weight loss?
The idea hasn’t simply appeared from nowhere. Researchers have been studying differences in the gut microbiome and looking at whether gut bacteria could be involved in obesity, metabolism and the way our bodies use energy.
That has led naturally to another question: if there is an association between the gut microbiome and body weight, could changing the microbiome using probiotics help somebody lose weight?
It’s an interesting question, but there’s quite a jump between something being biologically plausible and it becoming an effective weight-loss treatment.
This is where I think a lot of online articles go wrong. They’ll explain several possible mechanisms involving appetite, inflammation, fat storage or metabolism and, by the end, those theories somehow become “probiotics help you lose weight”.
The research hasn’t established anything that simple.
So, do probiotics actually help you lose weight?
The fairest answer at the moment is possibly a little, depending on the probiotic, but certainly not enough for me to consider probiotics a weight-loss treatment.
A large review published in 2024 brought together previous systematic reviews and meta-analyses looking at probiotics in people who were overweight or living with obesity. Overall, the researchers found statistically significant reductions in measures including BMI, body fat and body weight.
That sounds impressive until you look at the size of the difference.
The average reduction in body weight was around 0.6 kg.
That’s roughly 1.3 lb.
The researchers also pointed out that confidence in the evidence was limited because some of the underlying studies were small or weren’t particularly high quality.
More recent research hasn’t completely cleared things up either. Some analyses have found small improvements in BMI or body composition, while others haven’t found a significant effect on actual body weight. Different studies also use different probiotic strains, doses and treatment periods, which makes it difficult to turn the research into a simple recommendation for somebody standing in Holland & Barrett wondering which bottle to buy.
For me, that’s the important bit.
If somebody loses half a kilo more in a clinical trial, that’s scientifically interesting because it may help researchers understand the relationship between the gut microbiome and obesity. It doesn’t necessarily mean buying probiotic supplements is going to make a noticeable difference to your own weight-loss journey.
What about particular probiotic strains for weight loss?
You’ll often see particular names mentioned online, especially Lactobacillus gasseri, Lactobacillus rhamnosus and different Bifidobacterium strains.
Some have produced interesting results in individual trials or reviews, and researchers are continuing to investigate whether certain strains or combinations might have greater effects than others.
I wouldn’t, however, give you a shopping list of strains and tell you to go and buy them for weight loss.
The NHS makes an important point here: probiotics sold as foods and supplements aren’t regulated in the same way as medicines. We can’t always be certain that a product contains exactly the bacteria stated on its label, that it contains enough to have an effect or that those bacteria will survive long enough to reach the gut.
There’s also potentially a big difference between a precisely defined probiotic preparation used in a clinical trial and a tub of “gut health” gummies you found in the supermarket.
If future research identifies particular strains, doses and formulations that reliably produce clinically useful weight loss, then recommendations may become much clearer. At the moment, I don’t think we’re there.
Probiotic foods or probiotic supplements?
This is where I’d separate wanting to lose weight from wanting to include fermented or probiotic foods in your diet.
Foods such as live yoghurt and kefir can contain live cultures, while fermented foods including some sauerkraut and kimchi may contain microorganisms depending on how they’ve been made and processed. These foods can absolutely form part of a varied diet if you enjoy them and they agree with your digestive system.
I just wouldn’t eat them because I expected them to make me thinner.
If you’re choosing yoghurt, for example, there are other nutritional reasons it might be useful. Depending on the type you choose, it can provide protein and calcium and might make a convenient breakfast or snack. Those are much more practical reasons for including it than hoping the bacteria will somehow boost your metabolism.
The same goes for supplements. If you’ve been advised to use a particular probiotic for another reason, weight loss doesn’t need to be the deciding factor. What I wouldn’t personally do is spend significant amounts of money on a probiotic supplement purely because I wanted the scales to move faster.
Gut health is bigger than taking a probiotic
One thing I don’t particularly like about the way gut health is marketed is how easily something incredibly complicated gets reduced to buying a supplement.
Our gut microbiome is influenced by much more than whether we take a probiotic capsule every morning.
Diet is one part of that picture, and eating a varied diet containing fibre from foods such as fruit, vegetables, wholegrains, beans and pulses provides something rather less exciting but extremely useful: food for the microorganisms already living in your gut.
Some types of fibre are described as prebiotics because they’re used by beneficial gut bacteria. You don’t necessarily need a special prebiotic powder to get them either, because they’re naturally present in everyday foods.
This is another reason I’ve become increasingly sceptical of expensive products promising to “fix” gut health. Eating a greater variety of plant foods isn’t nearly as glamorous as a brightly coloured bottle promising a microbiome reset, but nutrition doesn’t always come with good marketing.
Can probiotics reduce appetite or food cravings?
This is particularly interesting to me because of my own experience with food noise and appetite.
There is research exploring the relationship between the gut microbiome, appetite regulation and the gut-brain axis, but I wouldn’t currently recommend probiotics as a way of controlling hunger or food noise.
I know from my own experience how dramatically appetite can change. When I tried Wegovy, one of the things that surprised me most was how much quieter my thoughts about food became. That was completely different from simply deciding that I was going to eat less.
That experience made me much more interested in the biology behind appetite, but it also made me more cautious about casually claiming that particular foods or supplements can control it.
If you’re constantly hungry or thinking about food, there are much more useful things to look at first, including whether you’re eating enough, how satisfying your meals are and whether you’re getting enough protein and fibre. Emotional eating and food noise can complicate things further, and I’ve written separately about both because they aren’t always the same as physical hunger.
I certainly wouldn’t expect a probiotic capsule to solve all of that.
Could probiotics still be useful if you’re trying to lose weight?
Potentially, but I’d look at why you’re considering taking them.
If you’re hoping that they’ll significantly increase the amount of weight you lose without changing anything else, the current evidence isn’t strong enough for me to recommend spending your money on them for that reason.
If you enjoy probiotic foods and want to include them as part of a varied diet, that’s different. Equally, if you’re considering probiotics for digestive symptoms, that’s really a separate question from whether they’ll help with weight loss.
The NHS says there’s some evidence that probiotics may help some people with IBS symptoms, although even there the effects depend on the particular probiotic and the individual.
This is something I think gets lost when products have several different health claims on the same packaging. A probiotic potentially being useful for one condition doesn’t mean every other claim made about probiotics automatically becomes true.
Are probiotic supplements safe?
For most people with a healthy immune system, probiotics generally appear to be safe, although they can cause digestive symptoms in some people.
The NHS recommends speaking to a doctor before taking probiotic supplements if you have an existing health condition or a weakened immune system.
I’d also be wary of assuming that “natural” means there can’t possibly be any downside. Supplements can still be inappropriate for some people, and if you’re taking them because of persistent digestive symptoms, it may be more useful to find out what’s causing those symptoms rather than continually adding different products and hoping one helps.
Would I take probiotics specifically to lose weight?
Based on the evidence we currently have, no.
That’s not because I think probiotics are useless or because research into the gut microbiome isn’t exciting. Quite the opposite. I think we’re going to learn a huge amount more about how the microorganisms living in our gut interact with appetite, metabolism and health over the coming years.
I just don’t think that automatically translates into “buy probiotics to lose weight”.
Having lost 10 stone myself, regained weight and subsequently explored medical weight management, my view of weight loss has changed enormously over the years. I’m much less interested now in finding the next ingredient or supplement that’s supposed to give weight loss a little boost and much more interested in the things that make a meaningful difference to someone’s everyday life.
If you enjoy live yoghurt, kefir or fermented foods, include them because you like them and they fit into your diet. If a healthcare professional has suggested a particular probiotic for a specific reason, that’s a different conversation too.
But if the only reason you’re considering an expensive probiotic supplement is because the advertising has convinced you that your gut bacteria are stopping you losing weight, I’d save your money for now.
The research is interesting. The marketing is considerably further ahead of it.
