How Your Gut Microbiome Impacts Insulin & Blood Sugar

Updated: Jun 24

Balance is key when it comes to creating optimal health in the body, and this includes blood sugar. Currently there is a great deal of discussion in health and weight loss circles about blood sugar stability and its impact on whole body health.


Diet and lifestyle factors can influence blood sugar levels.


For example, adopting practices such as crowding out processed foods, eating balanced meals at regular intervals throughout the day and increasing physical activity are all effective strategies for helping to balance your blood sugar. Which helps with weight loss!


But did you know that the bacteria in your gut also impact your blood sugar?


By adopting habits that enhance the health of your microbiome you can help support weight loss through key microbial actions.


In fact, researchers have predicted that dietary and lifestyle recommendations for weight loss in the future may include personalized recommendations based on an individual’s gut microbiota!



In this blog I’ll discuss the basics of blood sugar, as well as give a genrral overview of the key players in blood sugar regulation.

I’ll discuss factors that impact blood sugar as well, in particular the microbiome.


Lastly, I’ll share several microbiome balancing strategies I use with my clients to help them balance blood sugar and lose weight!


Blood Sugar 101

Blood sugar, or glucose is the fuel that keeps our cells alive and functioning. It powers our bodies the same way in which gas powers a car. We need it to survive.


Glucose is found in all forms of carbohydrates; simple sugars (like table sugar), refined flour, complex carbs, fruit, even a small amount of protein and fats that we eat are converted into glucose. But the primary source of glucose is carbohydrates.


Anyone who has done a low carbohydrate or ketogenic diet knows that the body can burn fat for fuel. But generally speaking most tissues prefer to run on glucose for fuel. This is particularly true for the brain, heart, and skeletal muscles.

How the body takes in sugar

In order for the cells to take in sugar, the pancreas produces insulin, the hormone that triggers the cells to take in sugar. Insulin can trigger sugar to be used for fuel or stored for later use.

You can think of insulin like a gatekeeper. The point of insulin is to regulate the level of sugar that’s circulating in the blood, while keeping fuel on hand for daily activities and any “fight or flight” situations.

Insulin acts as a key that opens the cellular door to let blood sugar in. When we have enough sugar in the blood to stay fueled, insulin triggers the liver and muscles to store blood sugar as glycogen.

In between meals when blood sugar begins to get low, the hormone glucagon triggers the stored glycogen to turn back into glucose. This provides immediate energy to keep us going through the day. This release also happens when we need a burst of energy for emergencies (fight or flight response).

Insulin is produced by the pancreas, an organ tucked behind the stomach, nestled between the liver and the spleen. Specifically beta cells in the pancreas are responsible for insulin production. As food is digested, glucose is released into the blood. This increase in blood sugar triggers insulin production.

In contrast, when blood sugar levels become low, other cells in the pancreas called alpha cells trigger the production of glucagon which tells the liver to convert glycogen back to glucose.


In this way, the body brilliantly keeps blood sugar levels tightly regulated, at least when things are working properly.


When the pancreas is unable to produce enough insulin, Type 1 diabetes occurs. This happens because beta cells are destroyed by the immune system and there aren’t enough “open doors” to let blood sugar into the cells.

In the case of Type 2 diabetes, too much insulin is common. In this condition the “keyhole” that insulin uses to open the “door” is gone, preventing cells from getting the fuel they need. This is what’s called “insulin resistance.”

In both cases the amount of sugar in the blood becomes too high. This causes stickiness and blockages in blood vessels from which the complications of diabetes arise.


Factors that affect Blood Sugar Balance

Blood sugar levels can be affected by:


At the most basic level blood sugar levels are heavily influenced by our dietary choices.

Simple carbohydrates like table sugar or products made from refined flour are rapidly turned into blood sugar. Over consumption of these foods for a lengthy period of time can derail healthy insulin and blood sugar regulation leading to the development of Type 2 diabetes.


When you eat too much sugar it forces the body to work harder to find balance.


Complex carbohydrates like whole grains, fruits and vegetables are also sources of glucose but they additionally provide fiber which slows down their digestion and the subsequent release of blood sugar.

Physical activity also exerts a powerful impact on blood sugar levels. More movement equals more fuel burned. Blood sugar levels can drop after exercise as a result of glucose being used for energy. Individuals who are more active (including non exercise based activity) have better insulin sensitivity. It’s why a sedentary lifestyle contributes to Type 2 diabetes.


Chronic stress also plays a role. Stress triggers the production of adrenaline and cortisol, both of which trigger the liver to release sugar. This is done to help the body deal with an eminent threat.


The body lacks the ability to differentiate between an actual life threatening emergency and something like a spousal disagreement or a pressing deadline at work. The effect is the same.


When stress is ongoing, blood sugar is often elevated yet it’s not being used for fuel hence how stress (cortisol) can cause belly fat.


Low blood sugar can also trigger a stress response. The body freaks out that it won’t have the fuel it needs. This is why it’s important to not go too long without eating, and why someone who struggles with emotional eating can be prone to binge eating if blood sugar gets too low.

It’s also why fasting isn’t always optimal for everyone. Long periods without food can trigger panic and over eating in some individuals.


Undereating, not eating at consistent times, and not consuming balanced meals are three things I see often in my practice. Typically addressing these three components alone helps bring blood sugar (and bodyweight) into balance.


Your microbiome also impacts blood sugar. The bacteria in your gut influence your appetite, your blood sugar production and the rate at which you burn sugar.

Remember gut bacteria eat sugar too!


In fact if they’re fed too much sugar, it may shift a healthy microbiome into dysbiosis. Too much sugar can allow for the proliferation of pathogenic bacteria and opportunistic sugar-loving yeasts like Cándida.

Lastly, your bodyfat affects blood sugar. The reverse is true as well. Blood sugar influences body fat and can play a role in obesity. Imbalances in blood sugar can cause weight gain and gaining excess weight can cause blood sugar imbalances. It’s a very viscous cycle that can be difficult to break.

In fact the link between the development of Type 2 diabetes and obesity is so strong and prevalent it’s been given the name “diabesity”.

Blood sugar also plays a role in satiety, or how “full” we feel after we eat. The control of appetite and energy expenditure is a complex process that involves crosstalk between the digestive, endocrine and nervous systems. It also involves hormones such as leptin and gherlin and nervous system sensors in the GI tract and brain.

Leptin, which you can think of as the fullness hormone is produced by the fat cells in response to insulin production. It signals to the brain that you’re full.

Insulin rises after eating a meal. Insulin stimulated glucose metabolism influences the release of leptin. This signals the hypothalamus to reduce appetite. Leptin also communicates with the hypothalamus and other nerve sensors to control calorie burn. When leptin levels are high it triggers a higher rate of calorie burning. When low, the reverse is true. It reduces calorie burning.


Leptins role in regulating appetite and calorie burning is also involved in the regulation of body fat content.


Leptin resistance is common in people who are obese.


This may sound counterintuitive but with excess body fat a person actually has higher levels of leptin. However the brain stops acknowledging the hormone's signal. This means that even though you have more than enough of the hormone available and energy stored, your brain does not recognize it and thinks you're still hungry. As a result, you continue to eat. This condition is now believed to be one of the main biological contributors to obesity.

This is a condition similar to insulin resistance in diabetics. Insulin resistance is even one of the triggers for leptin resistance.


Another hormone involved in appetite regulation is ghrelin, aka the hunger hormone. Think of a growling stomach when you’re hungry. That’s ghrelin.

This hormone is secreted in the digestive tract and it tells the hypothalamus that the body is hungry. The production of ghrelin is triggered when the stomach is empty. When the stomach is full it triggers a stop to ghrelin secretion.


Ghrelin contributes to the release of blood sugar by halting the release of insulin from the pancreas. Ghrelin also triggers glucose production in the liver. Both of these processes translate to higher levels of blood sugar.


What may be a surprise is that ghrelin levels are reduced in obesity which should mean that appetite is then reduced. We aren’t sure why this is exactly but it’s clear that insulin, leptin and ghrelin functions are disrupted in obesity.

Your Gut Microbiome & Weight

Human studies have observed that gut microbial composition varies between obese and lean individuals.


Obese individuals have less bacterial diversity in the gut overall and more Firmicutes, a type of bacteria that can negatively affect fat and glucose metabolism.

Obese individuals also have significantly less Bacteroidetes than leaner individuals.


Bacteroidetes are favorable in the gut because they produce short-chain fatty acids (such as butyrate) that are associated with lower levels of inflammation and protection from obesity.


Observed differences in gut microbes play a role in many factors that affect an individual’s weight, such as food cravings, hormones, and metabolic effects.

Food Cravings: It’s common to think that food cravings are often just a lack of willpower, but food cravings always have an underlying cause, whether emotional, mental, or physical.

One proven cause of food cravings is the composition of microbes in your gut. This is because some microbes have the ability to control host behavior (the behavior of the organisms they inhabit).


In fact, one study found that individuals who crave chocolate have certain microbial metabolites in their urine that individuals without chocolate cravings do not.

A diverse gut microbiome, which has been associated with a lower body weight, has less influence over host behaviors than a microbiome with less diversity because more energy is expended on competition between bacteria and less energy is expended on microbial “fitness,” which can occur when there are fewer varieties of bacteria in the gut.

When this happens, microbial populations manipulate host behavior in less favorable ways (such as cravings) to boost their own survival. One explanation for this is that gut microbes may influence taste receptors.


The best way to naturally support a healthy and diverse microbiome is through nutrition variety.

A diverse gut microbiota consists of different types of microorganisms (bacteria, fungi, viruses, etc.) that produce thousands of powerful compounds and coexist harmoniously in the gut.

Our microbial diversity has decreased through reduced food variety, eating highly processed foods, moving to cities where there isn’t dirt for us to play in, conventional farming practices, a reduction in soil richness, and of course, overuse of antibiotics.

Diet and lifestyle patterns are the biggest impact factors that influence the variety of bacteria in your gut. A healthy lifestyle and a varied diet allows for the preservation of microbial diversity, so to optimize your microbiome make sure to eat a diet with lots of variety.

Hormones: Gut microbes can also affect hormones that alter hunger and satiety levels, such as leptin, glucagon-like peptide-1 (GLP-1), and ghrelin.

This is hypothesized to occur in one of two ways: through production of peptides (or chains of amino acids) that mimic hormones affecting satiety or making antibodies (proteins) that can alter appetite directly.

Studies have found that gut microbes can influence leptin, a hormone that signals fullness and affects caloric expenditure.

GLP-1, another hormone affected by the composition of the gut microbiome, is needed to send nutritional and energy status signals from the gut to the central nervous system in order to control food intake.


Studies have found that microbial fermentation of certain types of fiber (such as oligofructose) increases GLP-1 concentrations in the gut.

Oligofructose, found in garlic and onions, may also affect ghrelin, a hormone that can promote hunger and weight gain. One study concluded that subjects who consumed an oligofructose supplement over 12 weeks had decreased ghrelin levels and lost more weight when compared to a placebo.

Metabolic Effects: Gut microbes not only influence what and how much we want to eat but may also influence our caloric expenditure from these foods.

For instance, animal studies have found that microbe-free mice weighed less than normal mice, even when they were fed the same diets. When microbes were transplanted into the microbe-free mice, they gained weight, even though the diet wasn’t altered. The transplanted microbes appeared to play a role in releasing calories from the diet and storing more energy in fat cells.

It’s important to note that few studies on these effects have been conducted in humans, making this an exciting area for future research.


It has been found that lower levels of Bacteroidetes in the gut (and higher levels of Firmicutes) increased caloric harvest from the diet by approximately 5% of total daily energy intake.

Certain microbes may be responsible for these metabolic effects.


For example, the bacteria Akkermansia muciniphila is associated with lower levels of obesity, diabetes, and other metabolic disorders.


Higher concentrations of A. muciniphila in the gut support a healthy weight by increasing fatty acid oxidation (breakdown) in adipose tissue and creating short-chain fatty acids, which affect energy and lipid metabolism. A. muciniphila may also support the integrity of the mucus layer in the gut.

Strategies for Balancing Blood Sugar Through Gut Health


I always begin with the gut, and when it comes to balancing blood sugar, there are a few key strategies I put in place to help support optimal microbial balance.


A healthy microbiome means more balanced blood sugar!


Crowd out processed foods: Earlier in this post I mentioned Firmicutes and Bacteroidetes. Differences in the levels of these microbes can play a role in body weight.


Higher overall caloric intakes (more likely with high-fat and high-sugar diets) are linked to obesity, loss of beneficial Bacteroidetes, and increased growth of Firmicutes. But when healthy diet changes are made - such as reducing the consumption of processed foods- levels of Bacteroidetes increase, aiding in weight loss.


Increase diversity of food consumption, especially fruits and vegetables: It’s been shown that individuals who consume

30 or more types of plant foods (fruits or vegetables) per week have increased microbial diversity in their gut.


Consider keeping a list of fruits and vegetables on hand to plan your meals and incorporate as many of these beneficial foods as possible.


Eat more polyphenols: This is a key point of focus in my GutHealthy program. Polyphenols are compounds that can enhance health in various ways, including cardioprotective and anticancer benefits. The quercetin in apples, epicatechins in cherries, and isoflavones in soy are all examples of polyphenols. Polyphenols, such as those found in cranberries and grapes, may help increase levels of A. muciniphila in the gut by creating an intestinal environment conducive for this beneficial bacteria to survive.


Eating a variety of fruits and vegetables of all colors will boost your dietary intake of polyphenols.


Choose anti inflammatory Omega 3 fats: Levels of A. muciniphila are also influenced by dietary intake of omega-3 fatty acids from fish

oil. Omega-3s are important for lowering levels of inflammation. Consider including fatty fish, such as cod, salmon, or tuna, in the diet often. Other great sources are macadamia, flaxseed, olive or avocado oils.


Consume prebiotics regularly: Prebiotics, such as oligofructose, are nondigestible food ingredients that feed the probiotics in your gut.

Prebiotics are found in foods such as apples, asparagus, chia seeds, garlic, and onions (among many others).


Studies have found that the appetite-affecting hormones, including GLP-1 and ghrelin, are modulated by prebiotics and that consumption

of prebiotic fibers are associated with increased satiety after eating.


Prebiotics are also linked to a reduction in the lipogenesis (fat storage) response of the hormone leptin.


Include probiotics in your diet. Probiotics are microbes that provide health benefits for their host. They can be found naturally in food or consumed through dietary supplements.


Probiotic-rich foods include fermented vegetables (such as sauerkraut or kimchi), yogurt, or kefir with live active cultures, and fermented soybeans (tempeh).


Studies have found that some probiotics, particularly Lactobacillus strains, minimize the amount of weight gained while consuming a high-fat diet.


Multistrain probiotics may be more helpful than single-strain probiotics for this effect, which is why including a variety of probiotic-rich foods (containing a variety of strains) can beneficial to the diet.


However I do want to mention that probiotic therapy is complex and highly bio individual.

Running to the local drugstore and purchasing a run-of-the-mill probiotic isn’t likely to help, and (depending upon your microbiome) may even worsen your situation. It’s very important to work with a certified health coach or other qualified professional when considering probiotic therapy.


Because not everyone tolerates prebiotic- and probiotic-rich foods equally, it is also important to introduce them gradually.

If you are immunocompromised or have a GI condition (such as IBD, SIBO, or IBS), you definitely would want to discuss probiotics with a coach or your healthcare provider.


Increase Physical Activity: Similar to the diet, physical activity can influence the composition of the gut microbiome.

Studies have found that exercise positively affects Firmicutes: Bacteroidetes ratios and the production of butyrate, a short-chain fatty acid important for energy metabolism.


When activity levels are increased, shifts in the gut microbiome have also been seen, including positive effects on both the types of beneficial bacteria found and the diversity within them.


While the benefits of physical activity on gut and overall health are undeniable, for many clients, it can be difficult to find the time to commit to regular exercise. To help create space for physical exercise in your week consider the following:


  • Set reminders on an electronic device to get up and move at regular intervals.

  • Schedule movement into your day the same as you would appointments.

  • Combine leisure with movement by finding hobbies that you enjoy and that encourage physical activity. This will help sustain your motivation to move over time. Consider bowling, dancing, gardening, or hiking.

  • Find a support person, such as a friend, family member, or health coach to help hold you accountable to your physical activity goals.

  • Ask someone to join you! Getting a friend, family member, even a pet involved in your goals can help keep you active. Walking or playing with your dog, meeting a friend for a walk in the park, or taking a yoga class with a co worker are all great ways to encourage you to be more physically active.

  • Work extra movement into your daily routine. Park your car farther away when running errands. If you have to walk to the mailbox, consider increasing your steps with a quick walk around the block before checking the mail. Suggest walking meetings with coworkers. Explore simple shifts in routine that will work best for you.

Be Mindful with Antibiotics: It’s important to maintain a healthy gut microbial balance for optimal health, blood sugar balance and a healthy weight.


Being mindful with antibiotics is one way to do this.


Antibiotic exposure prenatally or within the first year of life is associated with an increased risk of obesity in childhood.


This is important considering that by two years old children in the United States, on average, have received three courses of antibiotics!

But no matter when they are used in life, antibiotics disrupt the gut microbiome, leading to loss of beneficial bacteria. Antibiotics do a great job at wrangling infectious diseases, but at a serious cost. They decrease your microbial diversity since they not only target the specific pathogen causing an illness, they also destroy the beneficial microbes that we depend on to keep us healthy.

In my opinion over-prescribing and overuse of antibiotics is a huge contributor to the rise we’re seeing in chronic diseases.

Did you know that just one round of antibiotics decreases gut microbiome diversity by at least 30%?


And some research is finding this drop in microbiome diversity may actually be much greater.

Studies have shown this drop in microbiome diversity can affect weight, body fat percentage, short-chain fatty acid production, and metabolism of fatty acids.


Antibiotics are an important treatment modality for a wide variety of health concerns and may be necessary on occasion; however, there are significant health implications when they are overused.

Here’s what you can do:

  • Reflect on your own history of antibiotic use and how it may be impacting your gut microbiome today.

  • If antibiotics are warranted or being recommended, be sure to ask questions about possible alternative courses of action. It’s important to be well informed when making decisions about antibiotics. Get as much information action as you can and consider all your options.

  • If you do need a course of antibiotics, ask your provider about follow up care to help reinoculate the gut. What dietary strategies can you implement to help replenish the microbes in your gut? Should you look into probiotics?

The Bottom Line

  • Blood sugar balance plays a key role in weight loss.

  • Your gut microbiome impacts blood sugar

  • In addition to the basics (eating balanced meals at regular intervals throughout the day) you may also want to think about weight loss through the lens of gut health.

  • What practices do you currently have in place to boost weight-supporting microbes in the gut?

  • Are there opportunities for additional practices or shifts that can support your weight goals?

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