Globally, obesity has become an epidemic and a major public health concern.  According to The World Health Organization (WHO), obesity has tripled worldwide since 1975. In 2016, more than 1.9 billion adults were overweight. Over 4 million people died as a result of being obese or overweight in 2017.  The WHO defines obesity as abnormal or excessive fat accumulation that presents a risk to health. It is defined as having a body mass index (BMI) over 30. A BMI between 18.5 and 24.9 is considered ideal.    

Complications of obesity lead to a myriad of chronic illnesses. These include cardiovascular diseases like heart disease and stroke. Obesity can also lead to diabetes with its complications of blindness, limb amputations, and kidney failure. Obesity has also been associated with some cancers such as breast and prostate cancer.  While this information may sound depressing and hopeless, obesity is treatable and preventable. And if you’re struggling with obesity currently, there are things you can do to help improve your health outcomes, starting with achieving a good hormonal balance.

Good health starts in your gut 

Your gut is the vehicle that works to absorb all the nutrients that come from what you eat. You can think of your gut as one long tube that starts at your mouth and excretes excess and/or unused particles out the back of your anus. This might sound like too much information but it’s important to understand that your gastrointestinal tract is working from the moment you put something in your mouth to the moment you excrete waste. You also have what is called a gut microbiome that lines your gastrointestinal tract and serves as a communicator to how well you are digesting food, how well nutrients are being absorbed and how balanced your hormones are in relation to what your body needs.

Doctor and holographic bowel scan projection with vital signs and medical records. Concept of new technologies, body scan, digital x-ray, abdominal organs, modern medicine
From skin health to mental health, your gut microbiome communicates how healthy you really are. Also known as the “forgotten organ” your gut health is essential to your overall health.

Research has shown that gut hormones serve as key regulators of energy and homeostasis. Here’s some of the gut hormones that play an important role in keeping you at a healthy weight.

Ghrelin is known as the appetite hormone as it stimulates appetite. Some studies have found that ghrelin suppression is lower among obese persons compared to non-obese persons, resulting in obese persons still feeling hunger and the need to consume more food after a meal. Obesity results in an overproduction of ghrelin and increased food consumption.

Peptide YY (PYY) hormone is made in the small intestine and helps to reduce appetite and limit food intake. PYY has also been used as a therapeutic intervention in obesity.

Glucagon-like peptide-1 (GLP-1) is another hormone that acts as a satiety signal while also regulating gastric emptying (the amount of time it takes for food to empty from the stomach and into the small intestine). Studies have shown that in persons who are obese this hormone is inhibited. Similar to PYY, the satiety signals are decreased and gastric emptying is increased leading to poor satiety and the need to continue to eat even after a meal.  

Intermittent fasting favors a healthy gut 

While intermittent fasting is a popular way to lose weight, it provides additional benefits such as improved gut health. Intermittent fasting supports the gut to adhere to its circadian rhythm. This alone promotes good gut health and may help regulate your gut hormones to make you less hungry and to improve your metabolism. A recent study on gut microbiome and intermittent fasting found beneficial effects of fasting on metabolic markers. Researchers showed that intermittent fasting promotes white adipose browning and decreases obesity by changing the gut microbiome. This change from white adipose tissue to brown or beige is a beneficial reaction that helps to ameliorate obesity and insulin resistance. Another short-term study examined the variations of gut microbiome during Ramadan fasting. While longer term studies on gut microbiome and fasting are needed, this study found an increased amount of Akkermansia muciniphilia (a good bacteria that indicates good metabolic health) at the end of the Ramadan fasting period.

Our microbiome is significantly impacted by our environment and the foods we eat

In fact, the standard western diet has a major impact on the type of gut flora that we produce. A metagenomics study (metagenomics is the study of genetic material recovered directly from environmental samples) done in a Dutch population of 1135 participants found that higher intake of total carbohydrates was strongly associated with decreased microbiome diversity; this decrease also occurred with sugar-sweetened beverages such as bread, beer, and savory snacks. Meanwhile, microbial diversity increased with fruit, coffee, tea, vegetables, and red wine. (side note: the researcher in me is thinking that replicating such a study in a more diverse population might yield even more interesting findings, but that’s a side note).

Further, an epidemiological study found that persons who emigrated from their home country to the United States had a fourfold increase in obesity risk compared to those who remained in their birth country. Being a child of immigrants, I found this very interesting because although there isn’t much obesity in my family, there is a lot of hypertension and diabetes, all risk factors that go hand in hand with obesity. I also remember my father talking of how much healthier he was (before he passed away) when he was in Haiti compared to his years in the states. Now of course you factor in age, his life’s work, and all the stressors of raising kids, but after reading this I couldn’t help but also think about his gut flora and the microbiome he may have developed while transitioning his life to the United States.

Foods that can promote good gut health

Fiber, unrefined whole grains, fruits and vegetables, nuts, seeds, yogurt, polyphenol- rich foods like dark chocolate, green tea, red wine, and fermented foods like kombucha, kefir, and sauerkraut all help promote the growth of good bacteria. 

While there may be no huge dietary restrictions when you practice an intermittent fasting lifestyle, you want to make sure to add these into your diet. When we talk about gut microbiome specifically, consumption of dietary fiber has positive metabolic health effects including increased satiety, decreased weight gain, and lowered blood glucose and cholesterol levels, serving to reduce the risk of cardiovascular disease and type 2 diabetes. 

For my keto friends! I know those practicing a keto diet may oftentimes restrict plant-based carbohydrates like ground vegetables (beets, yams, carrots), legumes or most fruits which may have high net carbs since the ketogenic diet needs you to stay between 20-50 grams of net carbs per day. However, studies have shown that restricting plant-based carbs can have a negative effect on the gut microbiome. Fiber is important to the gut lining and to bacterial diversity. 

Ok, so for those who are not-keto, should you stop eating bread or your sweet treats? Absolutely not! And if you are keto, should you immediately stop living your ketogenic lifestyle? No way! However, it is interesting to learn about how all of this affects our gut microbiome but also how we can control it to an extent based on how much or how little of something we are putting in our bodies. Additionally, examining how all of it affects our weight. Because no matter what type of eating lifestyle you adapt if your gut is not healthy, you will have a hard time seeing your weight go down. Gut microbiome, the type of bacteria living in your gut directly impacts your weight, how you digest the foods you eat and your overall health. 

Final takeaways

  1. Our gut microbiome is influenced by everything around us; this in turn has a major influence on our weight
  2. When our gut microbiome is unhealthy, it may manifest in chronic illnesses such as: obesity, leaky gut, diabetes and cardiovascular diseases as well as poor mental health, poor sleep, and irritated skin.
  3. We have the power to improve our gut microbiome health through what we eat, by including foods high in fiber, unrefined whole grains, dark chocolate (my favorite) and even red wine. 
  4. Including intermittent fasting as part of a daily, weekly or monthly regimen is a great tool to use that not only improves gut health but helps to reduce risks of chronic diseases while also decreasing weight. 

Having this information will not only keep you in the know of what is happening in your body but also aid in keeping your gut lining strong and overall maintaining a healthy gut microbiome!


Martine Etienne-Mesubi, DrPH

I am a public health epidemiologist interested in the cross section of health and the determinants of health outcomes.
In my blog posts I discuss all things public health such as the social determinants of health, infectious and chronic diseases as well as nutrition and weight loss.

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