Close this search box.

Weight Loss: Is The Secret In Our Bacteria?

On the face of it there is no obvious connection between the microbes in our gut and being able to lose weight. We know these bacteria help us digest food but so what?

We now know that these little critters are important for many functions inside our body, including how our metabolism runs. They’re not just bystanders but active participants inside us.

So what happens if the wrong critters get in there? Could we be condemned to a life of type 2 diabetes and obesity?

What The Science Says

First of all there’s amazing new evidence emerging every day about the cool things our gut bugs do! Take a look at Five Surprising Things Your Microbiome Does For You

Overweight people have a ‘poorer’ microbiome than lean folk in that it’s less diverse with fewer different species of friendly bacteria. Also, different species seem to dominate than in lean people¹.

Our microbiome is like a rainforest or a coral reef, a complex and abundant ecosystem made up of thousands of species. The richer and more diverse the number of species, the stronger and more resilient the ecosystem is.

Many studies have shown that loss of diversity in the microbiome goes hand in hand with illness in different parts of our body, sometimes far from our gut.

Back to the question of weight loss: which comes first, being fat or having a crummy microbiome? Does being fat damage our microbiome or does having a damaged microbiome make us fat? 

Here’s a clue: if you transplant microbes from a fat mouse to a thin mouse, the thin mouse gets fat. Also, if you transplant microbes from a fat human to a thin mouse, the mouse gets fat².

This is huge, as it suggests that the poor microbiome causes the obesity, not the other way around. Yes, there are many factors involved in getting fat, but it appears our microbiome is in play as a major factor.

‘But I’m not a mouse!’

Sure, but mouse biology is similar to human biology, so we can’t just ignore the mouse studies while happily tucking into another round of donuts.

Will studies like these be carried out on humans? It’s more tricky as specially-bred sterile lab mice were used, and it’s impossible to create sterile humans. However it’s only a matter of time until more human studies expand our knowledge in this area.

Extracting Calories

Bacteria can change the amount of calories that are extracted from the food we eat. This weird fact suggests that bacteria can regulate our metabolism.

We also know that these bacteria effect the insulin our body produces, which has a knock-on impact on how much fat is stored.

The result potentially is that if we have too many of the ‘wrong’ bacteria, we will consistently draw more calories from our food than ‘normal’, making it much harder to lose weight, even if we’re active and watching our diet.

We look at this in more detail here: Are You Overweight AND Malnourished?

gut bugs fat

Yo-Yo Dieting

In another recent mouse study: changes to the gut microbiome brought about by obesity lasted for 6 months and predisposed the mice to rapidly regain weight³.

This suggests that being obese makes your microbiome poorer (see rainforest example above), and once it gets to this damaged state, it takes a while to get back to healthy, and in the meantime you’re at risk of getting fat again.

This may at least partly explain the dreaded cycle of yo-yo diet failure.

A Path To Obesity

In case you’re still sceptical about the mice, a recent human study found that overweight 7 year-old children had different gut flora when they were infants to those that stayed at a healthy weight.

This means the children’s microbiome went off course when they were infants and from that time onwards they were more likely to be overweight. With more studies we can work out how to prevent that.  

It also means it could be several years after your gut flora goes wrong that it leads to you becoming overweight.

Can’t We Just Kill The Bad Bacteria That Make Us Fat?

Unfortunately not, as no single species of bacteria is responsible.

This shouldn’t be a surprise now that we know our microbiome is an ecosystem. Resilience and balance come from having a huge diversity of species. We need to think in terms of rebuilding and nourishing, rather than killing.

As with rainforests and coral reefs, collapse generally doesn’t happen when one species is removed, but rather as a result of cumulative losses, each one gradually eroding the stability of the system.

Once healthy stability is lost, unhelpful species can move in. This is probably why we see different bacterial species dominating in obese people than in lean people.

There is currently a lot of interest around a species called akkermansia muciniphila, the loss of which may be a tipping point that leads to inflammation and obesity⁴.  Could it be a ‘keystone species’ that has a disproportionately large effect on our ecosystem, tipping us into obesity if we accidentally kill it?

microbiome weight control

Weight Loss Made Easier

Don’t panic! Changes to our gut bacteria are reversible. If we start looking after these little critters inside us, soon they’ll be back up and running.

In turn this will help us lose weight more easily.

Sure, it doesn’t get us off the hook for doing all the other necessary stuff to lose weight. We’ll still need to be active instead of sedentary, and we still need to eat fewer calories than we burn each day.

But getting our microbiome in order will give us a tailwind. The other efforts we make will then pay off with faster and more long-lasting results.

For action you can take today, check out my 6 dead-easy steps to switch your gut bugs from crummy to magnificent!

6 Dead-Easy Steps

  1. Eat more unprocessed, homemade food and eat less junk food.
  2. In particular eat less refined carbs like white bread, pasta, pastries, cereal, as the bad bacteria LOVE these.
  3. Take a good quality probiotic for at least 3-6 months.
  4. Have a little live, fermented food or drink – like yoghurt, sauerkraut or kombucha – with every meal.
  5. Don’t go crazy on the antibiotics! Be guided by your doctor, but you don’t need them as much as you think. Save them for real emergencies and instead try a natural antibiotic.
  6. Lifestyle – make at least one change today out of this list:  
    • Exercise consistently, light or heavy intensity, both help our friendly gut bugs.
    • Drink less alcohol!
    • Be less stressed!


  1. Shannon C. Davis Jagjit S. Yadav, Stephanie D. Barrow, Boakai K. Robertson 2017 Gut microbiome diversity influenced more by the Westernized dietary regime than the body mass index
  2.  Ed Yong, 2013 Obesity via Microbe Transplants
  3. Christoph A. Thaiss, Shlomik Itav, Daphna Rothschild, 2016 Persistent microbiome alterations modulate the rate of post-dieting weight regain
  4. MurielDerrien 2016 Akkermansia muciniphila and its role in regulating host functions


Thanks to East West Health for infographic extract


Whenever you’re ready to become a fully-fledged Gut Geek™ here are 4 ways we can help you heal your gut, get your sh*t together and transform your health

1. Subscribe to receive regular strategies and hacks that you can use TODAY

All our blogposts and social media are focused on bringing simplicity to the baffling world of nutrition and supplements. We also provide easy-peasy action steps that you can use to start seeing immediate improvement. Subscribe to get the very best of our content straight to your inbox!

2. Follow our daily social posts and video stories religiously

Our content is produced in a combination of written posts and video stories, all neatly tied together around the topic of the week. This gives you constant learning in manageable, bite-sized chunks.

3. Join us for a live online workshop

Head to our workshop registration page for info on our next free online training, and get ready to geek out

4. Join our coaching program

There’s nothing like 1-on-1 coaching to massively accelerate your progress and achieve the results you dream about! We’ll create your very own personalised gut-healing roadmap and then guide you through it. Just send us a message telling us a little about your current challenges and what you’d most like help with and we’ll get right back to you.

42 thoughts on “Weight Loss: Is The Secret In Our Bacteria?”

  1. This sentence was so key for me “Bacteria can change the amount of calories that are extracted from the food we eat.”

    I did not know this but it makes so much sense!

  2. Great article, I’ve been trying to loose weight for some time now and I strongly believe the issue lies within my gut health

  3. These are some excellent tips for losing weight but still in a healthy way. Eating properly and balanced diet is a must.

  4. I’m overweight because of more eating processed and junk food but last few weeks I’am starting to make a diet and do some exercise I hope it works thanks to this article I’ve learned something.

  5. Thankyou – such a great article! I find it difficult to choose a good probiotic as there are so many – refrigerated or non-refrigerated? Can you recommend a good one (or if that’s not possible to name brands – a few? or, what to look for in the ingredient list? ) Thankyou!

  6. What an awesome article the whole is greater than it sum, we should take care and nourish the gut bacteria that we have in order to preserve the healthy system in our body.

  7. Brittany Giles

    I just did a post about the importance of gut health! I am so glad that others are joining the cause! Great read!

Let us know what you think

Your email address will not be published. Required fields are marked *

Share this article

Help spread the word! Every share matters.

Other recent blog posts

5 Steps to Successful Detox!

If our gut isn’t functioning properly we end up carrying around a lot more toxins on a daily basis than we should be. These toxins can drastically affect the way we feel, lowering our defences to illness and contributing to chronic inflammation around our body.

3 Simple Steps to Reduce Your Child’s Sugar Cravings

Consuming tons of sugar is bad for the gut health of both children and adults but children can be hit hardest by sugar cravings. Here are 3 simple steps you can take today to reduce your child’s cravings

Kickstart Your Kids’ Gut Health

The early years of a child’s life are a crucial time for the formation and development of their microbiome. If the wrong microbes get into their gut, it can set them on a path to lifelong problems.

Probiotics and Our Magical Microbiome

It’s weird when you think about it… taking a probiotic means that we’re consuming billions of tiny live organisms that are going to make our body work better. So how does it work and how do we choose the best probiotic?

Brain Health Begins In The Gut

Mental health problems are complex with many contributing factors. There’s now mounting evidence that the state of our gut may be a MUCH bigger factor than we could ever have imagined.

The Shocking Ways Antibiotics Can Destroy Our Health

Although antibiotics save lives every day they are also now linked to some of the biggest health challenges of our age such as diabetes, obesity and cancer. Why? Because of how they lay waste to our friendly gut bugs.