Gut Bacteria and Weight Loss, the Surprising Connection…

Perhaps you’re counting calories and exercising, but you can’t seem to drop that stubborn spare weight around your middle. What are you doing wrong?

You may be surprised to discover that your gut bacteria could be holding you back in your weight loss goals. Continue reading and learn how to stack the weight loss odds in your favour.

Don’t Downplay Your Microbiome

It’s true that having a healthy microbiome is important if you want to stay lean and healthy. Interestingly, most of us growing up were taught that bacteria is bad, and that we should always wash our hands to avoid getting sick.

But we need bacteria if we want to continue digesting our food, producing vitamins, regulating our hormones, and eliminating toxic compounds from our body. And most of our bacteria live in our gut. In fact, you may be surprised (and maybe a bit disturbed) to know that up to 2kg of bacteria are living inside of you right now!

Just like the community you live in, diversity is healthy and makes a better environment for everyone. In fact, more than 500 different species of bacteria could be existing in your gut at this very moment.

Unfortunately, some of our gut's are less of a multicultural mosaic and more of a melting pot of uniformity. And there are some pretty serious implications for your health for not hosting a wide diversity of bacteria such as lowered immunity, allergies, acne, and obesity!

Be a Lean, Mean Microbiome Machine

According to Tim Spector, the author of The Diet Myth, if you want to be lean like your ancestors were, it’s important that you cultivate your inner gut garden to grow a wide diversity of gut bacteria. Conversely, the fewer strains of bacteria you have living in your gut, the more likely you are to be overweight.

This knowledge may seem counterintuitive to you. After all, isn’t weight loss a simple calculation of calories in minus calories out? Your doctor and your personal trainer have always recommended counting your macros and your calories to help get you attain a ‘healthy’ BMI. No one has ever suggested you get a fecal test done in order to assess whether your gut bugs are hampering your weight loss efforts.

New research being done is demonstrating the real repercussions of living with an unhealthy microbiome. Although some of this research is being done with mice, the findings should not be dismissed based on the assumption that we have nothing in common with our furry rodent friends.

For example, in one study a team of researchers took bacteria from obese mice and fed them to sterile mice (aka. bacteria-free). The newly inoculated mice put on a hefty amount of weight over the next two weeks even though they were eating less than before!

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Studies with humans have shown that obese people tend to have less diverse microbiomes than lean individuals. And not only that, but obese individuals are more likely to be hosting a bevy of firmicutes. Firmicutes are a type of bacteria that are needed to absorb fats. And the larger the number of firmicutes compared to bacteroidetes, their weight-shedding counterpart, the more difficult time you will have losing weight.

A more recent study has transferred fecal bacteria from humans to mice to monitor the effects on weight. Interestingly, the study demonstrated that lean mice could be made obese if gut microbes from obese humans were transferred to them. Conversely, gut bacteria transferred from lean humans could prevent mice from putting on weight.

Currently, there has only been one report of a human-to-human fecal transfer that resulted in weight gain. A woman in the UK received a fecal transplant from her daughter, who was overweight. Although the woman was a healthy BMI at the time, a year after the transplant occurred, she was 14kg heavier and unable to shed the weight despite a strict diet and exercise regime.

The Inflammation-Weight Gain Connection

You may be a bit confused as to how these bacteria are actually stimulating weight gain. How are these bugs creating fat when you’re already restricting your calories?

Well, the process is a bit more complex than simply bad bugs = weight gain. There is a mediating factor known as inflammation. You may be familiar with the kind of inflammation you see and feel like a sprained ankle or swelling from a bee sting, but you might not be familiar with the type of systemic inflammation that is the product of an unhealthy microbiome.

You see, when you have too many bad bacteria in your gut, their presence is accompanied by the production of a molecule called lipopolysaccharide (LPS). LPS is found on the cell surface of bacteria, and LPS triggers your body’s immune system, which automatically produces inflammation as a countermeasure against real and perceived threats.

In addition, this inflammatory response also results in insulin resistance as a result of your body pumping out large quantities of insulin. The problem with chronically elevated insulin levels is that it makes it difficult for the body to burn fat.

Finally, inflammation and insulin resistance are just two of the symptoms that co-occur with an abundance of bad bacteria. Another weight-gain risk factor results from the additional energy that is extracted from what are usually indigestible plant fibres.

Normally, in a well-balanced microbiome your gut bacteria will digest some of these fibres, producing short-chain fatty acids. But if you have a few too many bad bugs hanging around then more short-chain fatty acids will be produced, resulting in more energy coming into the body. In a nutshell, an unhealthy microbiome means your body is taking in more calories from the same amount of food.

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Bad Fats = Bad Bacteria

At this point, you may be panicking thinking that you have an army of saboteurs living in your digestive tract, slowly adding kilograms despite your best weight-loss efforts. Luckily, we do know some of the risk factors that can contribute to someone developing an unhealthy microbiome.

And bad fats found in processed and refined foods is the number one causative agent in the proliferation of the types of bacteria that contribute to weight gain.

Now just to clarify, it’s important to note that not all fats are bad, in fact it's quite the opposite. The low-fat movement that began in the 1980’s, where healthy fats were replaced with refined carbs and sugar, is not the answer to our current microbiome epidemic, not even close.

Studies that have demonstrated a link between high-fat diets, inflammation, and weight gain largely used inflammation-inducing fats including refined omega-6 vegetable oils (e.g., canola oil and soybean oil). And yes, by all means do your best to avoid these damaged oils whenever possible.

You may be scratching your head right now since you’re relatively sure your doctor has been recommending ‘heart healthy’ plant seed oils ever since you can remember. But soybean oil, canola oil, and other seed oils are not the saviors we’ve been lead to believe.

And if you really think about it, it’s a bit unnatural to eat seed oils because the fats in seeds don’t naturally come in a concentrated form. We have to use a very labour-intensive process in order to extract that fat, and this process damages the fat due to the application of such intense pressure and heat.

In fact, our ancestors were eating a lot more omega-3s than they were omega-6s (like those found in seed oils). Foods like grass-fed beef and wild fish are great sources of omega-3s, but unfortunately these foods are not a major part of our diets anymore.

Today factory farmed beef and fish tend to be lower in anti-inflammatory omega-3s because they are fed a high omega-6 diet. This is why it is so important to go for grass fed and wild options, to keep the ratios of omega-3s to omega-6s in check and in the process keep systemic inflammation at bay.

In addition to altering the composition of our microbiomes, studies have demonstrated that these unhealthy fats also contribute to heart disease, diabetes, cancer, and depression.

Just because bad fats result in bad bugs doesn’t mean you have to stick to a low-fat diet composed of dry crackers and oil-free salads. In fact, eating healthy fats like coconut oil, avocados, grass-fed butter, wild fish, and extra-virgin olive oil can result in the proliferance of healthy gut bugs. And the side effects of a healthy microbiome is lower inflammation and weight loss!

Blaming the Western Lifestyle

Although inflammatory fats play a big role in the overall balance of our gut bacteria, it would be foolish to attribute all of our weight woes to an increase in omega-6 fats. The western lifestyle, that has become standard practice in many industrialized countries, is not doing our microbiomes any favours. Some of the worst offenders of our modern lifestyle include:

  • Antibiotics: Medical practitioners’ liberal usage (read: overuse) of antibiotics has wreaked mayhem on our guts. Not only do these medications kill off the bad bugs that initially caused our illness, they eliminate all of our good bacteria as well. If you do have to take an antibiotic then make sure you double up on your probiotics afterwards.
  • Processed Foods: So many of us are trying to balance both a job, family, and activities that it can be hard to find the time to plan a healthy meal. It can seem so much easier to just pick up fast food or opt for pre-packaged foods that one can simply pop into the microwave. Unfortunately, these foods are all but devoid of fibre and they’re high in damaged fats and sugar. The result is a feast for the bad bacteria in our guts.
  • Chronic Stress: Your job is demanding, your kids are needing your attention, and you’re constantly dealing with the pressure of being the perfect spouse, parent, and citizen. All this stress adds up to chronic inflammation, resulting in a ripple effect of an unbalanced microbiome and weight gain.
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Why Calorie Counting Doesn’t Work

As you start gaining weight from an unhealthy balance of bacteria, you may be tempted to further cut your calories in a desperate attempt to prevent the weight from creeping on. But starving yourself also means starving the good bacteria in your gut. And in the long run, you could end up gaining even more weight from your extreme attempt to slim down. 

It’s a much better idea to try and alter the root cause of the problem than to try and force the weight off using extreme measures. The reason they call it yo-yo dieting is because although your weight will decrease temporarily, after you start eating normally again (which is inevitable) your weight will shoot right back up and even surpass your original weight.

How to Take Action Now!

So now that you’ve discovered that you may be harbouring a pack of inflammation-inducing, weight-increasing bacteria, what can you do about it?

Once you have these bad bugs, are you stuck with them forever, doomed to continue packing on the pounds no matter how much you diet or exercise? Luckily, there are a number of actionable steps you can take right now to change your microbiome for the better.


Eat Whole Foods: Whole foods tend to be higher in fibre, which is needed to feed the good bacteria in your gut. Focus on fibre-rich vegetables (like leafy greens) that tend to be low in sugar to keep your insulin levels balanced. A good rule of thumb is to make ⅔ of your plate vegetables, paired with healthy fats and protein.

Eat Resistant Starches: Eat more resistant starches like cassava, Hi-Maize, bananas, and cooled rice. Resistant starches can’t be digested and utilized for nutrition by your body, but they are a great source of food for the good bacteria in your gut. Watch this video to learn more about the benefits of resistant starch! Or you can read our article here.

Cut out Toxins: In this case, alcohol and sugar are the two you should remove first from your diet. Both are the favourite foods of the bad bugs that contribute to weight creep. It’s important to note that fruit, although sweet, does not have the same effect as refined sugar does on your microbiome. Fruit’s naturally occurring sugars are also paired with fibre so the overall net effect is positive as long as it is kept in moderation. You can read more about detox here.

Eat Healthy Fats: Remember, omega-3s and monounsaturated fats contribute to a healthy microbiome. Up your consumption of extra-virgin olive oil, avocados, coconut oil, and grass-fed butter. Avoid the damaged fats that are high in omega-6s like canola oil, margarine, and soybean oil. This can be easier said than done when you begin to realize that these processed oils are in most packaged foods because they’re so much cheaper than their high-quality counterparts. Check salad dressings, mayonnaise, and most packaged foods to ensure you’re not accidentally consuming these bad fats. You may end up having to make your own since high-quality options can be limited.

Eat Fermented Food: Fibre-rich foods like fruits and vegetables act like a prebiotic, meaning they supply food for the good bacteria in your gut. But if you really want to transform your digestive interior then you should definitely consider adding fermented foods to your diet. These foods will directly inoculate your gut with beneficial bacteria that can crowd out the bad. Sauerkraut, kimchi, miso, and kefir are excellent fermented options, and they’re relatively simple to make at home too!

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Supplement Wisely

Probiotics: If you can’t stomach eating sauerkraut or any other fermented foods then definitely consider a high-quality probiotic. Look for a probiotic that has a higher number of CFUs (colony forming units). Some probiotics won’t be worth more than the package it’s sold in. Look on the package to determine if there is a guarantee regarding the number of CFUs upon ingestion (versus when the probiotics were first produced). With my clients I recommend quality, well studied brands, with specific strains to suit the individual.

Omega-3 Fats: It was a lot easier for our ancestors to eat lots of high-quality omega-3 fats. Nowadays, the way food is produced and raised means it’s a lot more difficult for us to get the same levels of this anti-inflammatory nutrient. To ensure you’re getting enough omega-3s, take a high-quality fish oil everyday.


Make sure you get enough shuteye! This can be difficult when you’re working long hours and managing a family, but being well-rested is essential if you want a healthy microbiome. Sleep deprivation can have a traumatic impact on your good bacteria.

In fact, a study demonstrated that inducing sleep deprivation in normal-weight men resulted in a change to their gut bacteria and lowered insulin sensitivity. And these effects could be seen after only two nights in a row of poor sleep!

In addition, it has already been established that there exists a correlation between shift work and obesity. So if possible, set yourself a schedule that guarantees you’re in bed at a certain time to ensure you get the recommended 7-8 hours of sleep needed every night.

The Bottom Line

If you want to lose weight or prevent the scale from creeping up every year, you need to ensure you have a diverse and flourishing microbiome. Follow the aforementioned steps to revitalize your gut to get healthy and fit!

If your keen to get started, but feel you could do with a little extra guidance​. You may want to check out our Gut Heal & Nourish Program here.

  • Daniela says:

    Brilliant article !! So glad I'm under your care on board with all this and thoroughly benefiting !!!

    • Amanda says:

      Thanks Daniela, glad you enjoyed the article! I am so happy to be working with you. It is so great to see you and your family benefiting with my help. You have done an amazing job!

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