Is There A Link Between Gut Bacteria And Weight Loss?

Is There A Link Between Gut Bacteria And Weight Loss?

There’s no such thing as skinny bacteria or fat microbes, but your gut bugs still help regulate metabolism, nutrient absorption, and weight management.

It can be frustrating to watch friends eat whatever they like, do very little exercise, and still look fit. Yet, it might not just be amazing metabolic powers, because gut bacteria and body weight are linked in many ways. Read on to find out how.

Table of contents

Gut bacteria and weight loss 101

Your gut microbes may help you to maintain a healthy body shape and even hold the answer to why some of us are protected from obesity.

Your large intestine is a haven for trillions of mutually beneficial microbes that make up your gut microbiota. These gut bacteria form an ecosystem involved in vital functions like metabolism, hunger, and digestion.

Even though it doesn’t always receive the recognition it deserves because humanity has feared microbes since their discovery, your microbiome is important for many aspects of your body, including your weight.

In particular, a diverse gut microbiome is beneficial for your health. That's because different types of bacteria perform a variety of jobs in your colon, and thus, microbial diversity helps control your metabolism and in turn, your body weight.

However, if your intestinal environment is imbalanced, it can cause what is known as dysbiosis, and that’s not good for anyone. It can mean that you have lower levels of beneficial bacteria, more opportunistic pathogens, or reduced diversity – all of which can have an impact on your body.

Altogether, this can negatively impact your health and may even explain why you put on weight more easily than other people. But like your weight, gut microbial health is also influenced by your lifestyle. That’s right, food and exercise are also important for the diversity of your gut bacteria.

Microbes for weight loss: do they exist?

Search for skinny gut bacteria and you’ll actually read about microbes that reinforce the gut lining and modulate your metabolism.

Two gut bacteria are associated with lean body weight. Akkermansia muciniphila and Christensenella minuta are good gut bacteria for weight loss because they are linked with preventing weight gain and are often found in slim individuals.

Akkermansia can feed on the mucus that lines your gut, promoting its production which strengthens your intestinal barrier (a weaker gut lining is detected in people with obesity). These microbes also produce acetate, a short-chain fatty acid that helps regulate body fat stores and appetite.

You can try boost the abundance of A. muciniphila with prebiotic foods that fuel their activities. You probably eat some of these anyway, but increasing your intake could help the growth of Akkermansia in your gut and enhance your protection against obesity.

Foods to boost Akkermansia

  • Cranberries
  • Concord grapes
  • Black tea
  • Fish oil
  • Bamboo shoots
  • Flaxseeds
  • Rhubarb extract

Christensenella is also an emerging gut microbe associated with weight control. Like Akkermansia, it is abundant in the microbiomes of lean people, and scientists think it could be promising for preventing obesity, which is now considered a global health epidemic.

Christensenella is associated with your genetic makeup, meaning that to some extent, you have higher chances of finding this bacterium in your gut if your relatives have them too. Some people don't have them, and that's okay.

Microbes for weight loss
Only a microbiome test can accurately check your gut bacteria

So if your Atlas Microbiome Test didn't detect any, don't worry. You can still have a healthy microbiome without them because there are lots of other beneficial and probiotic bacteria that help regulate your metabolism.

However, strictly speaking, there are no weight loss bacteria. Instead, there is evidence that microbes indirectly act on our body fat composition. Researchers are already investigating how to manipulate gut health for weight loss purposes, so more findings are likely to emerge very soon.

☝️FACT☝️There’s no such thing as fat bacteria or skinny bacteria, what matters is microbiome composition, beneficial microbes, and functions.

How to change gut bacteria to lose weight

Beneficial gut microbes are happy to trade plant-based foods and healthy fats for their health-promoting services.

Getting 30g of fiber every day from plants of different colours (think red peppers, orange pumpkin, purple carrots, etc.) may also help diversify your microbiota which is good for your overall health.

This was shown by the results of the American Gut Project, in which people who ate 30 plant foods of different colours per week had the greatest microbiota diversity. You can read more about these foods in our guides:

Rainbow plant foods contain many different phytonutrients, like polyphenols, that help the body prevent free radical damage and inflammation. They also contain a variety of fibers for gut health. Both of these also nourish beneficial bacteria in the microbiota.

Gut health and weight gain: food matters

So, we now know two types of bacteria that prevent obesity, but what about gut bacteria and weight gain? Simply put, what you eat is a huge factor. In fact, changing your diet won't just change your weight, it's the fastest way to change your microbes too.

There are links between gut bacteria and weight. The gut microbiota of individuals who are overweight show patterns of dysbiosis compared to healthy individuals.

Ultimately, this is associated with inflammation and increased blood sugar levels because there is a greater extraction of energy from food. Equally, these two factors are linked to being overweight or obese, and so to is the Western diet because of its high levels of sugar and fat.

Research has also shown that following a natural plant-based diet reduces calorie intake, increases weight loss, and lowers metabolic markers. It also nourishes beneficial gut bacteria because plants contain lots of different prebiotic fibers.

In a study involving type II diabetes patients, a vegan diet was shown to be more effective at controlling blood sugar levels than a usual diabetic diet. And, in the plant diet group, calorie intake was lower, which meant weight loss was more rapid. Interestingly, the beneficial bacteria that thrive on plant foods are also associated with better blood sugar control.

Bad gut bacteria and weight gain: antibiotics

Dysbiosis of the gut microbiome can result from other factors too, like antibiotics. This type of medication is linked to weight gain because they disrupt the microbial communities in your gut, either by preventing and slowing bacterial growth, or killing them.

Yet, the link between antibiotics and weight gain isn’t really a secret. Industrial agriculture has known for decades that low doses of antibiotics can encourage animals destined for meat consumption to gain weight faster.

This experiment that has been replicated in mice, who share many similar microbiome and biological traits with humans. These findings have led scientists to believe that antibiotics help explain the striking increase in childhood obesity in recent years.

What is obesity and overweight by Mia Nacamulli for Ted Ed

Indeed, there’s plenty of evidence indicating that the microbial disruptions caused by antibiotic use is linked to the world’s obesity problem. Research has shown that being exposed to antibiotics early on in life can lead to long-term disruptions in the gut microbiome, causing metabolic changes as you grow and develop.

That’s because antibiotics don’t only act on a specific type of bacteria. So when your doctor prescribes them for a bacterial infection (if you follow the instructions carefully) the bacteria making you sick should be eliminated, but it can also affect your other microbes, including the beneficial ones.

☝️FACT☝️ Antibiotics can induce changes in the gut microbiome that can be detected 6 months and even two years after taking them.

How to improve gut bacteria for weight loss

Now that you know why diet counts for body weight and your gut bacteria, it's time to talk about physical activity. Because when it comes to exercise, people who lead a sedentary lifestyle tend to have a microbiome which lacks diversity compared to people who regularly get their sweat on.

Aerobic exercises, the ones that get your heart pumping - like walking, jogging, swimming, cycling, and dancing - increase the abundance of health-promoting bacteria like Bifidobacteria, Faecalibacterium prausnitzii, and Akkermansia muciniphila.

By doing so, you support gut barrier function, which can help prevent inflammation. These microbes also maintain the gut environment which provides stability for good gut bacteria and deters potential pathogens, all of which reduce the risk of dysbiosis and help alleviate gut microbial imbalances that are associated with being overweight.

Exercise also helps stabilise your metabolic markers, like blood glucose and blood lipids, at healthy levels and trains your muscles to consume more energy. This also helps regulate your body fat. That’s why regular physical activity helps you lose weight and stay lean.

Eat the rainbow for good gut bacteria

Put more colour in your diet to achieve a diverse microbial community in your gut, and at the same time, keep your metabolism in check too!

Eating plenty of fruits, vegetables, and whole grains is vital for your health, yet many of us are not eating enough. In fact, the western diet is so low in fiber that 73% of British people consume less than the recommended 400g of fruit and vegetables per day according to a 2014 study.

It’s called a phytonutrient gap. These natural plant chemicals are beneficial to our health and beneficial gut microbes. Fortunately, with a little effort, these foods can be easy to incorporate into your diet.

Colourful foods for microbiome and metabolism

Colour Foods Benefits
Red Apples, cherries, cranberries, red onion, tomatoes, red cabbage Anti-inflammatory properties, antioxidants, immune system support, abundance of good gut bacteria
Yellow Apples, bananas, lemons, ginger, yellow onions, corn Antioxidant properties, increase gastric emptying, healthy gut microbiome, reduces blood sugar balance
Orange Oranges, apricots, mangoes, carrots, turmeric, yams Antioxidant effects in fat soluble tissues, abundance of healthy gut bacteria, fertility
Green Brussels sprouts, green tea, olives, green apples, artichokes, greens, cabbage Antioxidant properties, healthy blood circulation, abundance of good gut bacteria
Blue-purple Blueberries, blackberries, prunes, purple grapes, purple cabbage, purple kale, plums Antioxidant properties, sustenance for beneficial gut bacteria

There is a lot of research that shows long-term weight gain is associated with a gut microbiome that lacks diversity – not consuming enough dietary fibre is a contributing factor to this. Luckily, by increasing your intake of rainbow foods, you can support your whole body, a healthy weight, and your gut microbes all at once.

Gut flora weight loss: the hard and honest truth

It’s not as simple as change your gut flora and lose weight. Rather, it’s the impact these microbes have on your body that affects weight loss.

Your gut bacteria have roles in your digestion, fat storage, and hunger, all of which can have major impacts your weight. But you can’t simply change gut bacteria and lose weight. No matter what you’ve read elsewhere, we’ve done the research, and it’s not a quick fix solution.

Changing gut bacteria to lose weight

Let’s face it, you’ve probably already googled “which gut bacteria cause weight loss”, and found a whole list of bacteria names or tips. But take it from us and our team of microbiome researchers (who have PhDs and many published scientific papers to their names), healthy and sustainable weight loss can be achieved with healthy eating habits, no by starvation diets and supplements.

Good bacteria for weight loss by Adam Nieścioruk
There's no magic bullet, spend your time and money on real food instead

Sadly, it’s true. There’s no such thing as a weight loss gut bacteria supplement (so please don’t buy one). The fastest way to have a significant and lasting positive impact on your microbiome is to eat a healthier diet with lots of fruit and veg, and importantly, less refined sugar, artificial sweeteners, and meat.

Basically, gut bacteria won’t directly cause you to lose weight. Instead, it’s the effects of their activities rippling through your body which can help lose, gain, or maintain your weight because they help determine how much energy your body absorbs, and also how hungry or full you feel.

The microbiome acts indirectly on body weight

Research shows that the composition of our gut microbiome has a role in regulating our body weight. It is estimated that 60% of the variation in our microbiota (compared to other people's) is a product of your environment, especially diet and antibiotics.

Plus, there are distinct differences in the composition of the microbiomes of healthy people and those who are obese, or have another metabolic disorder like type 2 diabetes. For example, diabetic individuals tend to have lower abundances of butyrate-producers in their gut.

These microbes break down dietary fibre and turn it into the short-chain fatty acids, some of which have anti-inflammatory functions. However, the western diet is notoriously high in refined sugar, animal fat, and very little plant-based sustenance.

Research also shows that butyrate has an important role in protecting us from inflammation, maintaining a healthy gut lining, and most importantly, regulating our metabolism and food intake. It does this by stimulating the release of gut hormones which signal to our brain that we feel full.

If you don’t have a gut rich in butyrate producers, it may actually be telling you you’re hungry, making you eat more (potentially unhealthy) foods to satisfy your hunger. Over the long term, this can encourage symptoms like high blood sugar levels and insulin resistance.

Gut flora and weight loss: The Take Home Message

Your gut microbiome is pretty special, and it’s completely unique to you. Ultimately, that means you have a great level of control over its composition and diversity. So when it comes to gut bacteria, weight is a modifiable factor.

Your lifestyle has a real impact on the diversity of your gut microbiome and your susceptibility to weight gain and obesity. Eating more plant-based foods, prebiotic fibres, and doing more physical activity can enhance your gut microbial function.

By doing so, you can increase the abundance of health-promoting bacteria, as well as their beneficial functions. And it’s this which will enable you to maintain a healthy weight, because your gut barrier will work effectively to protect you from inflammation and rising metabolic markers.

TIP☝Discover your gut bacteria's butyrate, dietary fiber, and obesity protection levels with the Atlas Microbiome Test.

Leanne Edermaniger
Leanne Edermaniger Science writer who enjoys laughing which is scientifically proven to help you live longer.

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