Probiotic supplements contain living microbes that scientists believe may provide benefits, like better gut and immune health. There is some evidence that they may help with weight loss, but not all studies agree.
Probiotics also occur naturally in fermented foods like yogurt and kimchi. Eating these regularly can help to improve your gut health and increase the diversity of beneficial bacteria in your gut microbiome.
There are many other supplements that claim to burn fat or support weight loss in other ways. But most scientific studies investigating these types of products are of poor quality.
Read on to find out more about the links between gut bacteria and weight, as well as what the latest science says about supplements for gut health and weight loss.
Probiotic supplements vs. food
Changing the balance of your gut microbiome in favor of beneficial bugs can help improve your gut health. But could it also help you to lose weight?
Scientists reviewing four existing studies found that probiotic supplements were not effective in reducing participants’ weight.
However, another review of 15 studies found that probiotic supplements were more successful than placebos for weight loss and reducing body fat. But the effects the authors found were small.
Many of the probiotics currently on the market contain bacteria that are easy to mass produce. But they may not necessarily be the best for your gut.
ZOE runs the largest research program of nutrition and the gut microbiome in the world, with over 10,000 contributors to date.
Our research shows that having more of the 15 “good” bugs in your gut is linked with better health and lower weight. Probiotic supplements available today don’t contain these 15 “good” bugs. The only way to get more of these bacteria in your gut is by changing what you eat.
Fermented foods like yogurt, sauerkraut, kimchi, kombucha, miso, and certain cheeses, are rich in probiotics.
Scientists can’t tell at the moment how much of the bacteria in these foods actually take up residence in your gut or whether they support the growth of beneficial bacteria in other ways.
As such, we recommend that you include fermented foods that contain probiotics in your diet. Eat these regularly — a little each day — to support your gut microbiome.
To look after your “good” gut bugs, you also need to feed them by including prebiotics in your diet. Prebiotics are fuel for your gut bacteria, and you can find them in lots of plant fibers.
Good sources of prebiotics are onions, leeks, garlic, bananas, asparagus, legumes, and whole grains.
The ZOE program tells you the best foods for your metabolic and gut health, including your personalized "gut booster” and “gut buster" foods.
Eating for your unique metabolism and gut microbiome can improve your gut health, with weight loss as a favorable outcome, without restrictive dieting.
Other gut health and weight loss supplements
Aside from probiotics, there are other supplements that carry weight loss claims. But do they really work and are they good for you?
L-Glutamine (or glutamine) is an amino acid — one of the building blocks of protein — that has been connected to improved gut health.
It’s found naturally in foods like tofu, fish, lentils, and beans, and has also been reported in some studies to reduce obesity, body fat, and other risk factors for heart disease. However, other studies have found links with increased appetite and long-term negative health effects.
Collagen accounts for one-third of the total protein in your body. You can get it from egg whites and bone broth, but the collagen from food or pills is not the same as the collagen that your body makes itself.
A small number of studies have linked collagen to a healthier intestinal lining and lower body fat. However, the research so far was conducted in cells and animal models. It’s not clear if the same would hold true in humans.
There is no good quality evidence to suggest that collagen promotes weight loss or better gut health.
Artificial weight-loss supplements that claim to burn fat are incredibly popular — Americans spend more than $2 billion on them every year.
But most of these products are not regulated in the same way that drugs are. They are also, on the whole, understudied, and there is limited evidence that they are a safe, effective way to promote gut health, weight loss, or general health.
Gut microbiome and weight
There are intriguing links between your weight and the health and makeup of your gut microbiome.
Your gut microbiome is the unique collection of microorganisms that live in your gut and play an important role in your health.
Our research has found links between the gut microbiome and body weight. We also found that everyone’s gut microbiome and the way their body responds to the food they eat is unique.
With the ZOE at-home gut microbiome test, you find out which bacteria currently live in your gut. The ZOE program uses this information — alongside measures of your personal blood sugar and blood fat control — to identify the best foods for your gut and overall health.
Unpublished data from ZOE shows that people who closely followed our personalized, gut-healthy nutrition program lost an average of 9.4 pounds after 3 months, and around 80% of them said they didn’t feel hungry and had more energy.
Gut health, bacteria, and weight loss
The 15 “good” gut bugs ZOE scientists have identified are associated with better gut health, lower weight, and less belly fat, and the 15 “bad” gut bugs are associated with worse health, higher weight, and more belly fat.
These “good” and “bad” bugs are also linked to other health conditions, such as reduced insulin sensitivity and higher blood sugar levels. These, in turn, are linked to weight gain and obesity.
From our research, we know that eating the right foods for your individual metabolism and gut microbiome can benefit your health. Weight loss can occur as a byproduct without restricting how much you eat, and it's more sustainable this way.
There is other research to support a connection between gut bacteria and weight.
In one recent study, 105 volunteers took part in a commercial wellness program. There were differences in the gut microbiomes of study participants who lost weight and those who didn’t.
The researchers saw fewer microbes overall — specifically those involved in breaking down nutrients — and more microbes associated with inflammation in volunteers who didn’t lose weight. Inflammation is a marker for a number of health conditions including obesity.
Another study involving 80 people with overweight or obesity found a link between the specific types of microbes in their guts and how much weight they lost on a calorie-restricted diet.
Losing weight can be very challenging. What constitutes an optimal moderate weight range will be different for everyone.
If you are considering losing weight, work with a healthcare professional to find out what weight range is best for your health.
There are many pills and supplements that claim to be miracle workers for weight loss. But there’s limited scientific evidence to suggest they can improve your gut health or help you reach a moderate weight in a safe, healthy way.
Some studies have found that probiotic supplements may aid weight loss, but other studies didn’t see the same effect. Many probiotic supplements contain bacteria that are easy to grow in large numbers. It’s not clear that they are the best for your gut health.
Eating a gut-friendly diet that contains plenty of fiber, prebiotics, and fermented foods rich in probiotics can help the beneficial bacteria in your gut to thrive.
Our data shows that eating for your unique microbiome and metabolism can lead to weight loss without counting calories or restricting how much you eat.
A core gut microbiome in obese and lean twins. Nature. (2009).
A high-protein diet for reducing body fat: mechanisms and possible caveats. Nutrition and Metabolism. (2014).
Baseline gut metagenomic functional gene signature associated with variable weight loss responses following a healthy lifestyle intervention in humans. American Society for Microbiology. (2021).
Can encapsulated glutamine increase GLP-1 secretion, improve glucose tolerance, and reduce meal size in healthy volunteers? A randomised, placebo-controlled, cross-over trial. The Lancet. (2015).
Collagen peptides ameliorate intestinal epithelial barrier dysfunction in immunostimulatory Caco-2 cell monolayers via enhancing tight junctions. Food & Function. (2017).
Collagen structure and stability. Annual Review of Biochemistry. (2009).
Comparing effectiveness of fat burners and thermogenic supplements to diet and exercise for weight loss and cardiometabolic health: Systematic review and meta-analysis. Nutrition and Health. (2021).
Consumption of fermented foods is associated with systematic differences in the gut microbiome and metabolome. American Society for Microbiology. (2020).
Dietary supplements for weight loss. (n.d.).
Effect of glutamine supplementation on cardiovascular risk factors in patients with type 2 diabetes. Nutrition. (2014).
Effect of oral ingestion of low-molecular collagen peptides derived from skate (Raja Kenojei) skin on body fat in overweight adults: a randomized, double-blind, placebo-controlled trial. Marine Drugs. (2019).
Effects of probiotics on body weight, body mass index, fat mass and fat percentage in subjects with overweight or obesity: a systematic review and meta-analysis of randomized controlled trials. Obesity Reviews. (2017).
Glutamine supplementation favors weight loss in nondieting obese female patients: a pilot study. European Journal of Clinical Nutrition. (2014).
Obesity and inflammation: the linking mechanism and the complications. Archives of Medical Science. (2017).
Oral glutamine supplementation reduces obesity, pro-inflammatory markers, and improves insulin sensitivity in DIO Wistar Rats and reduces waist circumference in overweight and obese humans. Nutrients. (2019).
Probiotics for weight loss: a systematic review and meta-analysis. Nutrition Research. (2015).
Richness of human gut microbiome correlates with metabolic markers. Nature. (2013).
Side effects of long-term glutamine supplementation. Journal of Parenteral and Enteral Nutrition. (2013).
The effects of caffeine intake on weight loss: a systematic review and dose-response meta-analysis of randomized controlled trials. Critical Reviews in Food Science and Nutrition. (2019).
The effects of green tea on weight loss and weight maintenance: a meta-analysis. International Journal of Obesity. (2009).
The intestinal microbiome predicts weight loss on a calorie-restricted diet and is associated with improved hepatic steatosis. Frontiers in Nutrition. (2021).
The role of glutamine in supporting gut health and neuropsychiatric factors. Food Science and Human Wellness. (2021).