To rise to the task of high-intensity exercise and long-distance races, the body must be well fueled or else it falters. But identifying exactly what nutrition you need to be well-fueled and avoid the bonk can be complex—and frustrating.
To date, science has explored the why and what of eating for performance, physiology, and metabolism, and ultimately accumulated enough data points to establish sports nutrition practices which work most of the time, for most athletes.
A Part of Hearst Digital Media carbohydrate-rich meal or snack before a workout, avoiding running on empty, and when you’re going for a long run, replacing spent fluids and food. Still, each runner, each environment, and each challenge often demands a different amount, type, and timing of fuel. The dynamic nature of training and environment can result in an eating plan that drove a great performance one day, falling flat the next.
Classically trained and with nutrition science top of mind, I’ve spent years translating available research into practice. I’ve advised tardy and late sleepers that eating on the way to a workout is better than nothing, that training on an empty tank will derail prime performance, and an hourly intake of 30 to 60 grams of carbs will lead to steady energy and fast finishes for long runs. These were my recommendations—that is until I started wearing a continuous glucose monitor.
What is a continuous glucose monitor?
Sometimes referred to as a glucose biosensor, a continuous glucose monitor (CGM) is a wearable device capable of measuring glucose 24/7.
A Part of Hearst Digital Media diabetes keep track of glucose levels in real-time and make changes to food or insulin delivery as needed.
In the not-too-distant past, understanding glucose levels required a finger stick or lab draw, with the resultant lab value representing one moment in time. Researchers and patients were limited in the ability to see a complete picture of glucose response to food or exercise. Naturally, the design of this testing method made it near impossible for researchers to capture minute-to-minute glucose levels throughout an entire workout, let alone an entire day.
Now, by using a quarter-sized biosensor which is applied to the back of the arm and remains in place for a set duration (usually about 15 days), we have the ability to continuously measure glucose levels.
When the biosensor is paired with a corresponding app, wearers receive data and insights into the effects that different events–like eating, exercise, mood, sleep, and other lifestyle choices—have on glucose levels.
My journey with a continuous glucose monitor
The biosensor I’ve been wearing is the Abbott Libre Sense (full discloser: it’s made by my former employer), and this wearable tech connects to the Supersapiens app. The system is available only in Europe, but I’ve been trialing it and using with clients through an Institutional Review Board-approved trial. (That’s the process that clinical trials and pilot trials use to approve a study.) But there are several different products on the market which pair a biosensor with an app, each designed to support a variety of health, wellness, and/or performance goals.
I’m often asked if a continuous glucose monitor hurts to apply or wear (no), and if there’s a needle that stays in my arm (definitely not). The biosensor captures glucose readings every minute.
When my biosensor pairs with the Supersapiens app, I’m able to see what my glucose is doing at any point in the day, and consequent performance during a workout. Shoes & Gear food choices A Part of Hearst Digital Media.
The continuous glucose monitor also tells me the brutally honest truth—like when my food choices (and sweet tooth) result in my glucose pattern looking like a roller coaster ride. Over time, I learn that my mood and energy levels Nutrition & Weight Loss.
How a glucose monitor can guide performance
While testing, I sit down to chat with Kristina Skroĉe, M.S., a sports physiologist at Supersapiens to better understand the reasons more athletes (like Molly Seidel) Races - Places.
Skroĉe agrees with my perspective that real-time, personalized data could be the foundation to accumulate small changes over time and thus fine-tune health and performance. A step-by-step approach can help wearers change practices, often as a result of seeing an immediate connection between food and lifestyle habits and the consequent impact on glucose and energy levels.
Sports-forward Supersapiens allows athletes to better connect the dots between pre-, mid-, and post-event fueling strategies, Shoes & Gear recovery. Without a continuous glucose monitor, an energy dip at mile two can be a crush to the ego, suggesting poor fitness. But thanks to wearable technology, the same athlete can connect premature fatigue The Benefits of Spirulina prerun meal choice, or poor nutrient timing. A biosensor can prevent hitting the wall at mile 15 or 18 or whenever, simply by monitoring glucose dips and allowing you to proactively add in more fuel, a sports nutrition and body positivity guide for female athletes.
As a practitioner, I’ve also noticed that if glucose levels remain steady and adequate, but performance still falters, we can eliminate fuel as a culprit. Instead, we look to hydration or sleep or other stressors Pamela Nisevich Bede MS, RD, CSSD, LD.
What I learned from wearing a continuous glucose monitor
While wearing the biosensor and exploring athlete data, the most eye-opening findings for me disproved some of my longstanding nutrition bylaws.
Nutrition & Weight Loss carb meals I’ve relied upon to provide fast, preworkout fuel (i.e. a toasted bagel, oatmeal and fruit, or even a sports drink and a banana), lead to significant post-meal spikes in glucose and a reactive energy low. If I add fat, protein, and fiber to the meal, though, the drastic spike and valley disappears.
If my stomach demands only simple carbs before a workout, I learned to eat earlier, allowing time for the food to be absorbed. Eating within an hour of a workout is off limits; the practice results in an energy spike and then valley as insulin gets to work shuttling glucose into the cells. As insulin is a fat-depositing hormone, high levels of circulating insulin also mean that I can neither freely access sugar, nor fat for an energy kick. The end result? I feel like I’ve hit the wall a few miles into a run while waiting for my glycogen stores to be released.
Thankfully, there’s a simple fix. Skroĉe explains that eating many hours prior to the workout (approximately two to four) leaves time for digestion and absorption, recovering from any post-meal energy plummet, and ultimately results in readily accessible fuel on board once the workout starts.
My experiment of one also provided invaluable insights into things I had suspected, but couldn’t previously confirm. For example, glucose levels, which can be equated to energy levels, increase but then falter soon after a sugary snack, leaving me craving another sugary snack and a hit of energy. Or that drinking a protein shake as a snack or enjoying a savory, not sweet, breakfast prevents a huge sugar spike and crash, ultimately affording me improved focus, plus less need for a nap hours later.
It’s intriguing to pull back the curtain and better understand what’s going on inside the human body. After weeks of wearing the biosensor, my personal response to foods becomes obvious: There are spikes and valleys after eating refined grains and sweets, whereas there is a flatter curve and steady energy following a meal high in fiber, protein, and fat. My runs are faster and I feel stronger when I add in fuel during the first miles of a long run, rather than waiting until the 45- or 60-minute mark.
While I realize my experience with a biosensor was unique to me, there are universal learnings that I readily share with athletes. For example, on long run days, add in fuel earlier, more often, and in greater amounts. Taking in 60 grams of carbs each hour, with 10 to 15 grams consumed every 10 to 15 minutes, results in glucose moving in the right direction (upwards to steady and not plummeting downwards). This feels like steady energy levels that keep the bonk at bay.
Recovering with adequate nutrition postworkout We earn a commission for products purchased through some links in this article recovery.
For general health, food choice and order matters. That is to say, consume foods with fiber and protein first, saving starches for last. While this practice makes sure that you’re consuming nutrient-dense Symptoms of Magnesium Deficiency protein, it also flattens the glucose curve. In doing so, eating carbs last and combining them with other nutrients effectively prevents glucose spikes, energy swings, and cravings.
Is a continuous glucose monitor for you?
Consider embarking upon your own glucose monitoring experiment if you’re curious about the impact of your diet on your health, energy levels, and performance. You’ll learn which foods, amounts, and timing keep glucose levels steady and performance on track.
You can also observe which habits result in feeling energized and focused, and even how to avoid jumping on a glucose roller coaster ride that’s certain to end in cravings and negative impacts on health.
In the past, you may only have had a snapshot into the foods and habits that were moving you toward or away from your goals. With a continuous glucose monitor, you could have an innovative tool to provide real-time feedback 24/7.
Recovering with adequate as a snack or enjoying a savory, not sweet, What to Eat Before a Long Run.
