Can the gut microbiome help weight management?

Excess weight is a major health issue which is driving a devastating rise in heart disease, type 2 diabetes, and non-alcoholic fatty liver disease.

A new study sheds light on how our bodies use calories, and how bacteria in our gut can help us control our weight!

The long-held wisdom of counting ‘calories in’ vs. ‘calories out’, when trying to lose weight, has been turned on its head by a team of US scientists.

Our gut microbiome – the 100 trillion microbes that live in our gut – is at the heart of the story.

Our gut microbes are at the heart of weight control

Researchers have found that our gut microbiome is the control centre for energy consumption. Our gut microbes help extract energy from food and produce energy sources that our cells can use.

Importantly, these gut microbes live in the far end of our digestive tract – our colon – and so rely on fibre-rich wholefoods that make it all the way through. Highly processed, ground or refined foods, on the other hand, are quickly absorbed in your upper digestive tract, which means more calories for your body and fewer for your gut microbiome.

Corbin and her colleagues (Nature Communications, May 2023) wanted to better understand the role of our gut microbiome in weight management and metabolic health.

In a small but rigorous study, people were fed one of two diets:

The Microbiome Enhancer Diet (MBD): designed to deliver more foodstuffs to the colon – the latter part of your digestive tract, where most gut microbes live

  • The MBD focused on 4 drivers:
    • Dietary fibre
    • Resistant starch
    • Foods with ‘large particles’ (larger chunks)
    • Limited processed foods

Western Diet: consisting of easily digested, highly processed foods

The MBD and Western Diet both consisted of equal calories, fat, protein and carbohydrates – only the quality of the calories differed.

Key findings from the study

Corbin et al found that with the MBD, less energy was available to us from the food we eat. With a typical Western Diet, more energy is made available – even though the total number of calories were the same for both diets. Hence the added potential for weight gain.

The QUALITY of calories is as important as QUANTITY – if not more so!

Also, the microbiome of people eating the MBD was different, with gut microbes producing more molecules called Short Chain Fatty Acids (SCFAs), that are essential for our well-being.  

Corbin explains: 
“On a Western diet that doesn’t feed the microbes very much, almost all the energy goes to us and very little goes to the microbes … We don’t give the microbes any opportunity to utilize the calories we eat because we use them all. We pull the rope all the way to one end.”


By eating a fibre-rich MBD style diet, you are not just feeding yourself, but also your gut microbes. We now know this effectively reduces the number of calories your body absorbs; and may also boost your general well-being.

NOTE: This does not constitute or substitute for medical advice! Seek professional healthcare advice as needed

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Sources and further reading:

All calories are not created equal when it comes to weight loss – The Washington Post

Host-diet-gut microbiome interactions influence human energy balance: a randomized clinical trial | Nature Communications

(Frontiers | The Role of Short-Chain Fatty Acids From Gut Microbiota in Gut-Brain Communication (frontiersin.org)