BlogHealthHow Does Gut Microbiome Affect Your Weight?

How Does Gut Microbiome Affect Your Weight?

7 mins read
Mariia Roza
Written by Mariia Roza on May 31, 2021
Dr. Olena Avdiievska
Medically reviewed by Dr. Olena Avdiievska

Your gut microbiome is an inner ecosystem that lives in your gastrointestinal tract. It consists of trillions of bacteria and other microorganisms. The microorganisms in your body outnumber your own cells 1.3 to 1. Diet is one of the most significant factors in determining your microbiome. Can you adjust the bacteria in your gut by changing what you eat? Let's find out.

Why is the gut microbiome so important?

Keeping your gut microbiome healthy is crucial because it affects your digestion, blood sugar level, immune system, and, essentially, your weight1. Over the last decade, researchers have realized2 the major part gut bacteria play in whether someone is obese or lean.

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How do gut bacteria affect weight?

One study3 compared twins where one twin was overweight and the other lean. Researchers found the overweight twin had fewer amounts and less variation of healthy gut bacteria compared to the lean twin. It’s like the obese twin’s gut was a simple garden with only a few dominant species, whereas the healthy twin’s gut was a wild forest teeming with an abundance of life.

What else in your body is affected by the gut microbiome?

Energy level

A diversity of good bacteria improves4 your ability to produce and absorb nutrients, increasing your energy. When you have enough energy, you are less likely to overeat or snack on fatty and sugary foods.

Gut bacteria affects your energy levels
Gut bacteria affects your energy levels


Inflammation can cause5 weight gain and make it more difficult to lose. There is evidence linking inflammation and the gut microbiome. Studies6 show that overweight individuals have higher inflammatory markers and lower gut bacteria diversity compared to non-overweight individuals. Furthermore, harmful types of gut bacteria can create chemicals that cause inflammation. Good types of gut bacteria, on the other hand, may stop inflammatory chemicals from passing from your gut into your bloodstream, decreasing inflammation and assisting weight loss.

Brain activity

Gut bacteria is your second brain
Gut bacteria is your second brain

Your gut and brain are intimately connected. Your stomach has even been called the “second brain.” You’ve probably had the experience of feeling queasy when anxious or getting butterflies when excited. What you may not know is that the connection goes the other way too. The bacteria in your gut produce chemicals7 that send messages to your brain.

There are two key ways the chemicals produced in your gut affect weight:

  • Your gut microbiome produces chemicals that affect whether you feel hungry or full. Thus, a healthy gut microbiome makes it easier to avoid overeating.
  • An unhealthy gut microbiome can send messages to your brain that exacerbate stress. Stress can increase your appetite and cause you to crave fatty, sugary, and salty foods over healthier options. An increased appetite plus unhealthy foods can mean overeating and weight gain. Furthermore, eating fatty, sugary, and salty foods can further hurt your gut health, creating a nasty cycle.

Foods that promote gut health

Probiotics are necessary for gut microbiome
Probiotics are necessary for gut microbiome

Several studies show people who eat a high-fiber diet8 have a healthier gut biome and lower body weight. There are two types of fiber: soluble and insoluble. While insoluble fiber is essential for your health, it’s a soluble fiber that affects your gut microbiome. Multiple studies show eating soluble fiber leads to good gut bacteria diversity, leading to a lower risk of belly fat.

Some great sources of insoluble fiber are beans, oat, apples, pea, barley, carrot, and citrus fruits. If you eat a wide range of whole plant foods, you will have good gut bacteria diversity.

Other foods may cause unhealthy bacteria to grow in your gut. Sugary foods, artificial sweeteners, and saturated fats promote harmful bacteria. If you’re craving a sweet treat, go for dark chocolate. Polyphenol-rich foods, like dark chocolate and red wine, are broken down by good gut bacteria, promoting their growth.

Summing up

A healthy gut can help promote weight loss and improve overall health. To build a better gut microbiome, cut back on sugary, fatty, and salty products and eat more high-fiber whole plant foods.

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By choosing high-quality sources, we make sure that all articles on the Unimeal blog are reliable and trustworthy

Sender R., Fuchs S., Milo R. (2016, August). Revised Estimates for the Number of Human and Bacteria Cells in the Body. PLOS Biology. DOI:10.1371/journal.pbio.1002533
Davis C. D. (2016, July). The Gut Microbiome and Its Role in Obesity. Nutrition Today. DOI:10.1097/NT.0000000000000167
Lee S., Sung J., Lee J. E., et al. (2011, October). Comparison of the Gut Microbiotas of Healthy Adult Twins Living in South Korea and the United States. Applied and Environmental Microbiology. DOI:10.1128/AEM.05490-11
Krajmalnik-Brown R., Ilhan Z. E., Kang D. W., et al. (2012, February, 24). Effects of Gut Microbes on Nutrient Absorption and Energy Regulation. Nutrition in Clinical Practice. DOI:10.1177/0884533611436116
Ellulu M. S., Patimah I., Khaza’ai H., et. al. (2016, March 31). Obesity and Inflammation: The Linking Mechanism and the Complications. Archives of Medical Science. DOI:10.5114/aoms.2016.58928
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Sudo N. (2019, April 25). Role of Gut Microbiota in Brain Function and Stress-Related Pathology. Bioscience of Microbiota, Food, and Health. DOI:10.12938/bmfh.19-006
Mayo Clinic Staff. (2021, January 6). Dietary fiber: Essential for a Healthy Diet. Mayo Clinic. DOI: