“I’m not even going to look,” I thought while spearing a mound of noodles and scooping them straight into my mouth. The continuous glucose monitor (CGM) I was wearing on my arm would tell me the story of how the sweet starchy carbs sent my blood sugar on a wild ride later. For now, I was feet up, bowl in hand, chilling with my family over a movie and Friday night takeout.
When I did fire up the CGM affiliated app to see the damage done, I was surprised to see none. My blood sugar response was a nice gentle bump, well within healthy ranges rather than the steep, pointy dagger I’d expected—and that I’d seen before eating similar dishes while working on deadlines at my desk.
This got me thinking, maybe how I was eating was just as important as what I was eating.
Sure enough, the pattern repeated. Happy, relaxed meals generally generated more mellow blood sugar responses. Stressed out, snarfing on the fly, tended to cause spikes, which left unchecked can lead to elevated blood sugar and pave the way for metabolic disease like diabetes, and over time can cause damage to blood vessels, nerves, and organs.
Sports physiologist Allen Lim, Ph.D., founder of SkratchLabs, who has been testing CGMs for a year, told me he had experienced the same results. A breakfast burrito consumed watching the sunrise yielded a radically different glucose response than one chowed down en route to the airport.
So, I was really interested when I saw a Levels blog post by Casey Means, M.D., cofounder and chief medical officer at Levels (which is another CGM system) on “how the mind controls metabolism.” In it she wrote:
“The thoughts in our heads have a direct impact on our metabolic processes, which are foundational for all aspects of health (if we don’t make energy properly, our bodies falter). Our cells ‘hear’ what we’re thinking through hormones and other signaling molecules triggered by what’s happening in the brain. And if your thoughts give your body a sense of threat (think: anxiety, worry, fear, trauma), it can impair metabolism.”
That’s because we’re hard-wired for survival. When your brain senses a threat—real or imagined; present like an intruder or virtual like a Twitter troll—it trips the “fight or flight” alarm in your hypothalamic-pituitary-adrenal (HPA) axis, which prompts a surge of stress hormones like adrenaline, norepinephrine, and cortisol, which in turn triggers a release of glycogen (stored glucose) from the liver so you have the energy you need to get out of harm’s way.
This hormonal milieu can also make you temporarily insulin resistant, so you keep that blood sugar coursing through your veins, Means explains in her post, so your body can conserve energy for the upcoming “fight or flight.” Eating in a stressed state, like driving in the car or on deadline at your desk, may exacerbate this effect in some people (like yours truly). This can also set up a negative feedback loop, where the brain isn’t getting the energy it needs, negatively impacting your moods and setting the stage for more stress.
Continuous glucose monitoring is very much in its early stages, but one of the things that we’ve learned from it and that surprises experts, like Lim and Means, is how difficult this stress response can make it to maintain stable glucose and insulin levels no matter how careful we are with our diet or how much we exercise.
“The little stressful events that may seem minor are deeply affecting your homeostasis and you can’t hide from that,” Means tells Bicycling. “If you’re stressed 10 times a day, you get little cortisol and glucose surges throughout the day that become built into your glucose curve. So, your baseline levels could be higher.”
The Exercise Part of the Equation
As an active cyclist who likely rides and trains hard, you’re also exposing your body to regular bouts of stress. Exercise is typically considered “good” stress, of course, and done overtime can help you be more stress resilient. But if you pile it on and don’t allow yourself to rebound and recover on a regular basis it can turn the corner and become “bad” stress and usher in elevated cortisol and glucose levels.
That may partly explain why endurance athletes can struggle to have optimal blood glucose levels. According to InsideTracker, which analyzes blood and DNA samples to help athletes maximize performance, only 23 percent of their users have optimized glucose levels—meaning many highly active people have elevated glucose levels.
Though research has shown that being a high-level athlete appears protective against diabetes later in life, one thought-provoking study published in 2016 found that a large percentage of sub-elite athletes tested had prediabetic blood sugar levels throughout the day, despite training at least six hours a week.
“Athletes subject themselves to a lot of chronic physiological stress, and it’s unclear what role this plays in metabolic outcomes,” Means says. “But we don’t tend to study populations who aren’t sick and follow them over time, so this is new territory and we’re still figuring out what it all means.”
These findings do, however, highlight the importance of recovery practices to bring the body and mind into a more relaxed state, so you can heal and rebound, Means says. “Recovery is really important to signal to the brain that we’re not in threat.”
Beyond Blood Sugar
Elevated blood sugar isn’t the only negative consequence of eating in a stressed state. Research shows chronically elevated cortisol can lead to impaired digestive function, including abdominal pain, increased intestinal permeability (a.k.a. leaky gut), and decreased ability to absorb micronutrients like vitamins and minerals from your food.
Even temporary stress can compromise your ability to digest your food properly compared to eating when you’re completely chill.
In one study from the late 1980s, researchers had a group of volunteers drink a mineral-rich beverage while in a relaxed state and again while one person was speaking to them about intergalactic space travel in one ear and another person was talking to them about financial planning in the other ear. They were able to easily absorb 100 percent of the drink’s nutrients when they sipped it in peace but had a significant reduction in absorption that lasted up to an hour afterward when they drank the beverage while exposed to the conflicting chatter.
Set Your Mind and the Table
Obviously, when you’re fueling during a race or hard ride, you’re going to be sucking down sugar in an amped up state. That’s okay because your muscles are tossing those carbs into the furnace as quickly as they’re coming in. But outside of exercise, your goal should be calm energy consumption. How to make that happen:
Eat in peace
Whenever possible, sit down and eat in a relaxed setting with a relaxed state of mind. Research shows it can help with digestion and GI disorders and as mentioned, may also help keep your blood sugar in check.
“This is one of the reasons I’ve been consistent in my mindfulness and breath work to regulate my nervous system,” Means says. “It’s the flywheel: When you regulate your nervous system, you have better metabolic health, better moods, better performance, and improved brain function.”
The key is activating the parasympathetic (a.k.a. rest and digest) nervous system, which supports digestion by increasing your salivary secretions and by stimulating your gastric juices, digestive enzymes, and bile so you can extract and absorb all the nutrients you need.
Do breathwork regularly
One of the simplest ways to activate your parasympathetic nervous system on demand is deep breathing. Research suggests that alternate nostril breathing, where you close one nostril and inhale for six seconds, hold the breath for six seconds, and exhale out of the opposite nostril for six seconds and then repeat in the opposite direction, may help you maintain that more relaxed state and achieve optimal digestive function.
Or you can try slow diaphragmatic breathing, Means says, noting that this is her go-to strategy for summoning a calm state of mind. Diaphragmatic breathing stimulates the vagus nerve, which can reduce stress, anxiety, anger, and inflammation, according to a report in Psychology Today.
Means suggests doing breathing exercises throughout the day to bring down stress, but you can also do it before a meal to summon a more relaxed state before eating.
Take a walk post-meal
When you’re done eating, take a short stroll, which is another traditional practice that science shows can keep your blood sugar in check. “Even a short walk helps,” Means says. “Walking activates our huge muscle groups that cannot move without creating ATP from glucose. Walking is a massive glucose sink that activates trillions of cells that pull that glucose out of the bloodstream and consume it so it doesn’t gum up the works.”
Just like all those little episodes of stress can lead to chronically high blood sugar, all these little stress and blood sugar relievers can have the cumulative effect of keeping your average blood sugar levels in a healthy range and help maintain good physical and mental health.
