Studies Show That Your Waist Size Is Linked to Your Gut Bacteria

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Losing inches around the waist is one of people’s constant struggles. Some have tried everything from exercise to plastic surgery. However, scientists recently discovered that gut flora also plays a part in defining the measurements of this body area, as hard to believe as it may sound.

Bright Side wants to pass on to you some scientific findings that connect the environment of bacteria in our intestines to how our abdomen looks.

Gut Flora 101

This is how experts refer to the set of bacteria that live in our gut. Each of us hosts about 100 billion, almost all of which inhabit the colon. They develop from birth and are normally harmless when they maintain a balance. However, they can cause trouble when they lose their fragile balance if they undergo some alteration that makes them multiply or disappear.

They constitute a sort of second DNA since each of us carries approximately 40 trillion bacterial cells, while our bodies are only made up of 30 trillion other types of cells.

The role they play in the human body

Since they’re so plentiful, gut bacteria contribute significantly to human health, as their main function is to absorb all the nutrients found in food. And their job doesn’t end there. They’re connected to our bodily functions in a manifold of other ways:

  • They encourage vitamin production, such as Vitamin B, K complex, and different amino acids.
  • They capture the necessary minerals, such as magnesium and iron.
  • They help our body defend itself against viruses and other dangerous bacteria, “teaching” gut bacteria to identify which strains belong to the body and which are invaders.
  • They metabolize certain carbohydrates, making them digestible for humans. Plus, they ferment those they cannot metabolize and coordinate a correct bowel transit.
  • They’re associated with human longevity.

This is how gut bacteria influence our waist size

Bacteria’s main job is to protect human health. However, being overweight has many negative health effects. So, how is it that they can also help us develop obesity? Some studies seem to have found the answer, though it’s still too early to reach definitive conclusions, according to their authors.

Gut bacteria are responsible for extracting energy from food. According to research, the absorption capacity of nutrients can vary from person to person, since the composition of gut flora grows differently in each of us.

Another study was carried out to decipher the connection between people’s different gut microbiota, obesity, and which agents influenced bacteria composition.

Feces from 393 pairs of twins were compared to determine if genetics played a role. They used this type of sample because fecal matter carries cells that expose the gut microbiota. They concluded that genes only influence 1/5 of the gut transit, while environmental causes are responsible for 68% of the change in the bacteria ecosystem.

These analyses also concluded that gut flora partakes in the body’s fat storage process, so a more efficient type of gut microbiota, one that better absorbs nutrients, could also cause weight gain and an increase in height.

In addition, it was determined that a high-fat diet can alter the microbiome and make it more prone to developing obesity. These bacteria also have a 6% influence on triglyceride variation and a 4% influence on cholesterol variation.

However, although high levels of fat in the body constitute one of the major risk factors for heart problems, another study suggests that there’s a closer association between gut flora and cardiovascular system behavior.

Although these are just initial studies, the doctors who conducted them also found that conditions like hypertension could be related to low diversity and a small number of bacterial communities. They tested this by relocating bacteria from people with the condition to healthy individuals, who began to display higher blood pressure.

Gut flora is also associated with the growth of the atherosclerotic plaque, which blocks arteries in a process known as atherosclerosis, facilitating the growth and rupture of said plaque. Finally, an altered microbiota can affect the arteries’ ability to widen and allow for blood flow, making the condition worse.

How to prevent these health problems

Doctors essentially recommend adopting a healthy lifestyle in every way, while still maintaining a focus on a healthy diet. Try the following:

  • Reduce your sugar and fat consumption by avoiding processed foods, as these promote the growth of harmful bacterial colonies. Opt for fruits and vegetables instead (5 servings a day), as well as foods that are rich in fiber, as they contain complex carbohydrates that help beneficial bacteria to flourish.
  • Drink lots of water to keep your body free of impurities.
  • Eat small amounts of food several times a day. The intestines are cleaned about every 2 hours, and it’s better to not make them overwork.
  • Consume prebiotics, foods with nutrients that feed good bacteria. Among these, you can include bananas, garlic, artichokes, and more.
  • Take probiotics, which are foods or supplements that contain living microorganisms that improve your health if taken in adequate amounts. Yogurt, kefir, kombucha, sauerkraut, and other fermented products are part of this list.

In rare cases, such as the total loss of beneficial bacteria from the use of antibiotics, doctors could transplant fecal microbiota from a healthy person to a patient who needs it.

Did you know that bacteria had so much influence on your body? What other benefits would you add to the list? Tell us in the comment section, and share this article with your friends!

Please note: This article was updated in July 2022 to correct source material and factual inaccuracies.
Illustrator Ekaterina Gapanovich for Bright Side


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This was a fascinating article until it got to the recommendations. These are horribly outdated, unscientific, useless epidemiological claims. This is bad nutritional advice.

Lc/hf or lc/hp is the way to go. Animal based. Kefir, probiotic yogurt, and a very specific set of veggies (sauerkraut/kimchi, brussel sprouts, broccoli) and meat - this is the optimal human diet, and fantastic for gut health.


This is good to know! I was looking to slim down this year and stay healthy, so thanks for the advice


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