Six factors that affect glucose besides food

Diet is a significant driver of blood sugar, but factors like exercise and stress also play a significant role. Here are six key glucose levers



In last month’s newsletter, I delved into how to build metabolically healthy meals. Although what we eat is incredibly important, food isn’t the only tool we have for optimizing glucose (blood sugar) levels. From increasing physical activity to getting more Zs, here are six additional things you can do to boost your metabolic health.


1. Exercise

Exercise provides both short-term and long-term metabolic health benefits. In the short term, it helps move glucose out of your bloodstream and into your cells, which is why doing moderate exercise after eating can help blunt a blood sugar spike.

Which exercise to do? Honestly, just move your body. Yoga, resistance training, HIIT training, lower intensity “zone 2” training, and walking all have metabolic benefits. Don’t overthink it. Let’s pause here and do five squats together (seriously)!

When you’re active, your muscles take in glucose immediately. Although they can access stored glucose (glycogen), they also take it in from your bloodstream. Exercise makes your cells more sensitive to insulin and improves the movement of sugar into cells by boosting the number of glucose transporters on the lining of cells (GLUT4 channels).

In the long term, regular physical activity increases the number of muscle cells, which means more mitochondria to turn glucose into energy. This is one of the benefits of resistance training: more muscle means more glucose utilization at baseline.

Being sedentary has the opposite effect. Several studies link sitting too much throughout the day to more inflammation and increased insulin resistance. We want to move frequently, not just in one intense spurt once a day. A study looked at walking for 30 minutes once per day versus walking for just 1 minute 40 seconds every 30 minutes. While both groups walked a total of 30 minutes, the frequent short walks were more effective at reducing post-meal glucose peaks and insulin levels.

What You Can Do:
Move as much as you can throughout the day, even if that means a few squats or walking for a couple of minutes every half hour. For your workouts, there is evidence that lower intensity zone-2 training (around 60–70 percent of max heart rate) for several hours per week can aid mitochondrial health. Additionally, working major muscle groups with resistance training is important for building strength and muscle mass. HIIT training can also be a powerful tool in our cardiovascular training and mitochondrial health.

For the 77 percent of Americans who are not getting enough physical activity, let’s make it more simple: find activities you love that involve moving your body or lifting heavy things and do them a lot. Aim for at least 150 minutes per week of aerobic exercise, and at least two sessions per week of resistance training across major muscle groups.

I like to start my day at a treadmill desk, usually for about an hour, and then alternate sitting or standing at my desk the rest of the day. I also walk around my house a few times as a reset between tasks or calls. My Chief of Staff Sonja and I encourage each other to do a minute of jumping jacks, squats, pushups, or ab work when switching tasks, every half hour or so.

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2. Stress

Stress prompts a hormonal response that increases glucose levels. When you’re feeling frazzled, angry, or panicked, your body may ready itself to fight off a threat by mobilizing ample glucose in your bloodstream for your muscles to use. To increase blood glucose, your body releases more adrenaline, cortisol, and glucagon, and consequently, your cells become insulin resistant. That’s why research shows a link between perceived work-related stress and increased levels of circulating glucose.

“If you have a sense that your mental and physical well-being could be better, and you’re not quite sure why things are off, there may be toxic or chronic stress or unresolved trauma in your orbit. 

Chronic stress may lead to prolonged insulin resistance because your body is frequently coping with elevated levels of cortisol. In addition, many people overeat or choose less-healthy foods when they’re stressed, which can further elevate glucose levels.

However, research has found that regularly practicing deep breathing might lower glucose levels by activating the body’s parasympathetic nervous system, aka the “rest and digest” system. In one study, 20 sessions of diaphragmatic breathing lowered participants’ cortisol levels. This, in turn, can lower glucose levels.

What You Can Do:
First, let’s pause and take a deep breath together. I promise it will feel good. Inhale four counts through your nose, feeling your belly expand. Hold for four. Exhale for four.

While we can’t avoid all of life’s challenges, we can manage our stress response with the right tools. We may not even realize we’re stressed because it has become our baseline (I’ve had so many patients tell me they are “not stressed,” but when they list their life stressors and the impact these factors have their life, it’s off the charts!) If you have a sense that your mental and physical well-being could be better, and you’re not quite sure why things are off, I’d guess that there’s toxic or chronic stress or unresolved trauma in your orbit. It’s there for most of us. I believe that one of our jobs is to identify and work on these elements of our lives, and ultimately, heal them. Tactics like diaphragmatic breathing and meditation can help, but we often have to go much deeper.

In a previous newsletter—How the mind controls metabolism—I discussed the need to address the root causes of our stress to truly achieve health, as well as my favorite tactics for managing stress. Remember, if your body perceives consistent and regular “threats,” it will be difficult to be optimally healthy. And threats are everywhere, from daily annoyances, to losing loved ones, to systemic injustice, to the certain knowledge that we ourselves will die. A tendency toward hypervigilance and control may start early in childhood, and we may not even recognize it. Yet it may be the lens through which we view almost everything in our life, lending stress to the simplest of daily routines. Doing the deeper work through tools like therapy, coaching, and other modalities can be monumentally helpful in gaining freedom from chronic stress and the need for control.

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3. Sleep

Research shows that sleep quantity and quality are vital for optimal metabolism, insulin sensitivity, and glucose variability. One study on healthy young men offers a compelling glimpse at this connection: After five nights of sleep deprivation—four hours of sleep per night—study participants exhibited metabolic profiles that resembled people with prediabetes. The men showed signs of impaired metabolism and insulin resistance, and the rate of clearing sugar out of the bloodstream was 40 percent slower than when they were well-rested.

A large body of evidence also connects sleep loss and poor sleep to the development of obesity and diabetes, due in part to the impact of sleep on several hormones. Sleep deprivation for just six days can increase cortisol, which can elevate blood sugar. Cortisol also decreases insulin production from the pancreas and reduces insulin sensitivity in the body, so glucose is less likely to be taken up by cells and remains in circulation.

When you sleep, your body also produces balanced amounts of ghrelin and leptin, two hormones that impact appetite and satiety. If you don’t get enough quality sleep, you may produce too much ghrelin. That can indirectly lead to higher glucose levels by prompting you to overeat. And research has shown that people who are sleep-deprived often crave sweets and starches (this is 100% true for me).

Lack of sleep can also increase inflammation, which contributes to insulin resistance, leaving blood glucose levels elevated. Additionally, lack of sleep increases levels of C-reactive protein, an inflammatory marker in the blood. Other studies have found sleep deprivation also decreases daytime secretion of inflammatory cytokines IL-6 and tumor necrosis factor-alpha (TNF-a).

What You Can Do:
Prioritize getting enough quality sleep, and keep yourself accountable with a sleep tracker. How much sleep you need is individual, but research indicates seven to eight hours is optimal for metabolic health. Set boundaries around your sleep time no matter how busy you feel.

This is my biggest struggle, to be honest. I have trouble getting to bed at a consistent time, and often stay up late writing (like right now!), as I feel most creative at night. One trick: I set weekly sleep consistency goals and share screenshots of my data with two of my best girlfriends for added social pressure.

Additionally, with Levels being a remote, asynchronous company, with virtually no meetings, it allows for more flexibility on wake-up time: if I stay up late writing, I can sleep in a bit and work when it makes sense for me. This doesn’t solve the important sleep consistency factor but helps with getting consistent quantity.

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4. Microbiome

Your gut microbiome refers to all the microbes (bacteria, viruses, and fungi) that live in your intestinal tract. We want to strive for microbiome diversity, as it plays a critical role in metabolic health.

Your gut produces sensor hormones, called incretins, that detect incoming food and prompt the body to metabolize it. Glucagon-like peptide 1 (GLP-1) is an incretin that tells the pancreas to release insulin, which lowers blood glucose levels.

Research suggests that gut microbiota interfere with incretin secretion in people with metabolic health problems. For instance, there are significant differences in incretin production between people with Type 2 diabetes or prediabetes and those without.

Short chain fatty acid (SCFA) production is also important. SCFAs form in the digestive tract from specific gut bacteria fermenting non-digestible fiber. The amount of fiber and type of bacteria in the gut impact how much of these beneficial fatty acids we produce. Butyrate, for instance, has anti-inflammatory properties, promotes fatty acid oxidation, and the upregulation of “uncoupling proteins” that positively impact mitochondrial function. People with Type 2 diabetes don’t produce as much butyrate as people without diabetes. Excessive inflammation may lead to insulin resistance and worse glycemic control.

The American Gut Project published research showing that people who ate more than 30 different types of plant foods per week had healthier and more diverse microbiomes than those who ate 10 or fewer per week.

What You Can Do:
Aside from putting good stuff in our gut, we also want to avoid harmful things. This includes excessive or unnecessary use of NSAIDs (like ibuprofen) and antibiotics (which wreak havoc on the microbiome and, in turn, our metabolic and mental health), pesticides, and added sugars. When you eat a whole-food-based, metabolically optimized diet, you’re less likely to need NSAIDs and antibiotics, as your body should suffer less pain and fewer infections.

Optimize your diet for gut health by taking in more probiotic fermented foods (sauerkraut, kimchi, and non-dairy unsweetened yogurt are my favorites) and prebiotics (the fiber and polyphenol rich foods that feed your microbiome). I aim for four to six servings per day of fermented foods, based on this recent paper in Cell, and about 50 grams of fiber per day.

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5. Light

Just as food is molecular information for our bodies, sunlight is energetic information that tells our brains and cells how to function (discussed in the recent newsletter, 5 Ways sunlight affects your metabolism). Our eyes are the brain’s access port to natural light. In brief, photoreceptors (light-sensitive cells) in our retinas receive and react to a particle of sunlight. A cascade of events then sends an electrical impulse to the suprachiasmatic nucleus (SCN) and other parts of the brain. This stimulates parts of the SCN to kick off genetic, hormonal, and neurotransmitter-mediated processes that affect the activity of the brain and nearly all cells in the body.

One primary function of the SCN is to operate as the body’s master clock or pacemaker. It’s involved in our sleep-wake cycle—also known as our circadian rhythm—which impacts everything from food intake, insulin sensitivity, glucose control, and energy expenditure.

When we expose ourselves to “irregular photic signals”—think: erratic sleep, being indoors too much, blue light emitted from our electronic devices late at night—the complex processes triggered by the SCN become distorted and can negatively impact nearly all physiological activities.

A small study from Northwestern University found that blue light exposure in the morning and evening negatively impacts glucose metabolism, with nighttime light being more problematic for glucose tolerance. Even a single night of too much artificial bright light can increase glucose and insulin.

Most of us are not getting optimal natural light exposure to properly signal our SCN. And the result is dire for metabolism. This lack of alignment with natural light cycles contributes to pancreatic dysfunction (the organ that makes insulin), issues with glucose and fat metabolism, and increased risk of cardiovascular disease, cancer, obesity, and Type 2 diabetes.

Less exposure to sunlight is also linked to lower serotonin levels, which can negatively impact mood. Serotonin also plays a role in metabolic regulation and related diseases. Increased serotonin signaling appears to help decrease appetite and improve glucose control.

We also get the majority of our vitamin D, aptly known as the sunshine vitamin (which is really a steroid hormone) from sunlight. We have vitamin D receptors in almost every cell. Vitamin D has strong impacts on metabolic health, yet many people are deficient in it. Low vitamin D levels are associated with obesity, insulin resistance, diabetes, and more. We need more research on the exact mechanisms through which vitamin D impacts metabolic health, but the hormone does have an anti-inflammatory effect. Additionally, research shows that it may increase insulin secretion from pancreatic beta cells. While many labs say that anything above 30 ng/mL is normal, many precision-medicine practitioners recommend aiming much higher, like 40 to 80 ng/mL.

What You Can Do:
Aim to get a dose of sunlight, even just a few minutes, first thing in the morning, if possible. Window glass blocks a significant amount of light, according to Stanford neurobiologist Andrew Huberman, PhD, so try to actually get outdoors. Generally, try to spend more time outdoors throughout the early and mid part of the day, as well. Also, avoid artificial light from devices—and bright lights in general—for a couple of hours before bed each night. By doing so, we signal to the SCN the time of day and set up our bodies to time genetic and hormonal signals appropriately. I talk more about my sunlight exposure habits in this article from The Proof Wellness.

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6. Environmental toxins

This one is a biggie, so listen up! The chemicals you eat, breathe, and are exposed to can impact your metabolic health in a massive way. There’s even a term for this now: “obesogens” are metabolism-disrupting chemicals in the environment that directly increase fat mass.

landmark paper on this topic came out just last month with Levels advisor Dr. Rob Lustig as an author. It concluded that these chemicals are not just associated with obesity but mechanistically cause obesity. It found that exposure to obesogenic chemicals is an under-recognized factor in the obesity pandemic, caused by largely unregulated industrial chemical additives. Dr. Lustig has said that 15 percent of obesity may be directly attributable to these chemicals. They can even affect our eggs and sperm to have a heritable detrimental impact on future generations.

“Don’t aim for perfection, because perfection is a myth. You can build these into your lifestyle over time by making them habits.”

These chemicals are found everywhere in our products: can linings, receipts, vinyl flooring, all plastics (even if BPA-free), personal care products (like shampoo, sunscreens, perfume, lotion and makeup), food preservatives, many drugs (including antidepressants), clothing (polyester is made of plastic), nonstick cookware, furniture, flame retardants, mattresses, toys, electronics, home disinfectants, air pollution, and pesticides.

Obesogens have a wide array of actions that all can work together to damage metabolism.They can impair the microbiome, alter hormonal control of eating behavior, affect thyroid function (which is closely involved in metabolic rate), change our epigenetics (the expression patterns of our genes), cause gene mutations, drive inflammation and oxidative stress, impair circadian rhythms, affect sirtuins (key longevity genes), and affect hormone function by blocking or activating hormone receptors.

Certain additives in processed and ultra-processed foods in the U.S. may also cause potential health problems, including inflammation. Read more on some of the most problematic ingredients here, including:

  • Potassium bromate and azodicarbonamide (ADA) in bread, crackers, and baked goods
  • Brominated vegetable oil (BVO) in some sodas
  • Titanium dioxide in baked goods, dairy products, salad dressing, and chewing gum
  • Yellow 5, Yellow 6, and Red 40 food dyes in candies, cookies, cereals, yogurt cups, and cakes

What You Can Do:

  • Avoid pesticide exposure by choosing organic foods when possible. (If you can, join a community-sponsored agriculture cooperative, or get whatever is on sale and organic and the grocery store!)
  • Eat a nutrient-rich whole food diet—the Mediterranean diet has been shown to be beneficial for minimizing toxin exposure.
  • Include cruciferous vegetables, such as kale, bok choy, cauliflower, broccoli, and cabbage, to help with detoxification pathways.
  • Minimize plastic use and opt for glass or other materials for storing kitchen, household, and personal care items.
  • Use cast iron cookware instead of nonstick pans, which can leach chemicals.
  • Opt for unscented home and personal care products ( is a good resource). I love unscented organic castile soap from Dr. Bronner’s for dish, hand, and body soap, and organic coconut and jojoba oil for moisturizer. “Perfume” or “Fragrance” are wildly common ingredients on nearly every personal care or home care product, even many products at health food stores. Avoid them and read labels. Organic essential oils are an acceptable exception!
  • Filter your air, which has been shown to have a positive clinical effect.
  • Certain supplements may also be protective, like vitamin C, curcumin, and resveratrol.
  • Get into nature and fresh air, away from car exhaust. And if you smoke, seek support to quit!

Final Thoughts

I get it: focusing on all six of these factors at once can feel overwhelming. Don’t aim for perfection, because perfection is a myth. You can build these into your lifestyle over time by making them habits. Repetition builds an intentional routine, which is what forms a habit. So set aside time after a meal to go for that walk. Eventually you will head out the door without even thinking about it. This Harvard Business Review article suggests “temptation bundling,” pairing the behavior you want to turn into a habit with something you enjoy. An example would be listening to your favorite song or podcast while on that walk. I really like the books Atomic Habits and Tiny Habits as great motivators for fitting more healthy habits into life. You’ve got this!