Is your gut microbiota plotting to make you obese?

Aside from genetics, the key to good health is a healthy diet and exercise right? Well it may be time to think again.

Your gut microbiota (collective term for gut microbes) influence how healthy you are and what type of foods you crave to eat. So they could be making you obese!

Your gut microbiota is critical to help you digest food, synthesise complexes and metabolise essential nutrients. The complex story of gut microbiota is just starting to unravel with a great ‘Gut reaction’ piece covered recently on the ABC Catalyst program. An increasing number of studies are revealing some of the influences your gut microbiota has on:
• the body’s signalling system which tells you when you are hungry or when you are feeling full
• how quickly food passes through the gut
• obesity
• inflammation and autoimmune diseases
• allergies
• autism
• multiple sclerosis
• mental health.

A study published in Nature highlighted the importance of gut microbiota and body weight. The influence of gut microbiota and weight gain was highlighted with initial studies looking at weight gain in germ-free vs. obese mice. When comparing microbiota, obese mice put on more weight than germ-free mice despite being fed an identical diet. When the germ free mice were given the same gut microbiota as obese mice (by ingestion of faecal matter from the obese mice), they also put on more weight when compared to the initial germ-free mice.

Resisting cravings isn’t a matter of self-control

Microbes have a preference for what nutrients they need to make them happy. Having a diet high in particular food groups or nutrients will encourage populations within your gut to flourish. A recent publication in Bioassays identified the possibility of microbes in the gastrointestinal tract influencing host mood and behaviour to eat the foods they need to thrive.

Gut microbes are manipulative and may influence your food choices by:
• influencing hosts through hormones
• inducing anxiety or dysphoria
• modulating host receptor expression
• influencing host through neural mechanisms.

The exact mechanisms of how that is achieved is still unknown, our gut is linked to a range of systems including the immune, endocrine and nervous system. Therefore our gut microbiota may be able to influence any or all of those systems.

E. coli

Electron micrograph of a cluster of E. coli. Image credit Eric Erbe [CC BY-NC-SA 2.0] via Flickr

So what is a healthy gut?

A healthy gut should contain a diverse range of microbes with ability to breakdown a range of different foods. Calories and exercise alone are not the answer to a healthy gut. Healthy eating with a varied diet high in complex carbohydrates promotes good microbes in your gut.
Obese individuals are often associated with unhealthy eating behaviour and lower diversity in gut microbiota.

Good news, you can change your gut microbiota

Your microbiota is a constantly evolving population of microbes which are heavily influenced by what you feed it. Products containing live bacteria that are beneficial for our health are called probiotics. Yoghurt, fermented foods and nutritional supplements are common sources of probiotics. Consuming these probiotics on a regular basis could help to balance the good vs. bad bacteria in your gut.

Fermented pickles

Fermented pickles a great source of good bacteria : Image credit Chiot’s Run [CC BY-NC 2.0] via Flickr


Yakult another great probiotic: Image credit Jepster [CC BY-NC-SA 2.0] via Flickr

Taking prebiotics are another way to improve your gut flora. Prebiotics are food for probiotics. They are commonly found in asparagus, Jerusalem artichokes, leeks, onions, beans, chickpeas, lentils and supplementary fibres such as psyllium, pectin, guar gum and slippery elm.


Probiotic soup: Image credit Clara Maria Ines [CC BY-NC-ND 2.0] Flickr

The next time you reach for a packet of chips or a chocolate bar, consider something to help out your microbiota instead.

5 Responses to “Is your gut microbiota plotting to make you obese?”

  1. moralesc says:

    As jrozek I really enjoy to know about updated info in nutrition issues. Is a so complex topic to discuss, I mean, people can’t quit to sleep or breath, but there is no controversy around that like for eating habits and food effects. Is like a never ending topic to work with, our systems are so complex, and there are investigations in microscopic/molecular levels improving every day.

    Is just fascinating how our allergies, weight, even psychological issues rely on such little things

  2. rpoon1 says:

    Thanks jbreadsell, the Catalyst story was my inspiration to write this blog and also to increase the fibre content in my own diet.

  3. jbreadsell says:

    I found your piece really helpful in understanding what microbes are and why they are good. I loved this Catalyst episode which I’d watched previously, it was so interesting and I was delighted to see a post about it. Personally, I found the link they discuss in the show with gut bacteria and asthma to be really interesting. The fact that asthma in mice improved with a high-fibre diet is something I’d never come across before in asthma management.

  4. rpoon1 says:

    Hi Jrozek. I think people on strict diets like the paleo or gluten-free would have microbes in their gut that grow well with those sources of nutrients. They probably won’t have the microbes (or maybe just in low numbers) to be able to break down and digest carbohydrates or gluten.

    I don’t know what the science is around sticking to specific diets in the long term. It could result in the development of intolerances if the microbes that were previously there before the diet die off, so the microbiota are no longer able to process the carbohydrate or gluten that they were previously able to eat.

  5. jrozek says:

    We’re being controlled by our gut bacteria?!? What the.

    I love hearing about the growing research on nutrition. There’s so many diets out there with iffy credentials- paleo, gluten free (for non-coeliacs), raw, clean….- that I would love to see torn to shreds with science. For example, if good gut bacteria need complex carbs, what does the gut bacteria of someone doing a ‘keto’ or Atkins diet look like with no carbs?