Levels Health review: optimize your fitness with a $400 glucose tracker

“What is that thing on your shoulder?” has been the question I’ve been asked most frequently for the last month. Understandably so. For the last 30 days, just barely peeking out from under the sleeve of my T-shirts, there has been a big black sticker. It’s round, about two inches in diameter, and it looks like a high-end Band-Aid. But that sticker is just a cover. Under it is a smaller plastic disk, with a little thread that is actually sticking into my body and analyzing my ever-changing blood-sugar levels. It’s the closest I’ve ever been to cyborg status. 

Levels Health is a new product and service — currently in late-stage beta but gettable by the public — designed to monitor your body’s glucose response to different stimuli, like exercise and stress and especially the foods you eat. It’s sort of like a Fitbit for your metabolic health, and it currently costs a hefty $400 for the one-month program. It’s aimed toward athletes and the health-conscious who are looking for everything from optimum performance to simply staying healthy.

Glucose monitoring devices like these are traditionally used by diabetics, who need to know their blood sugar levels and when to administer insulin or treat for low blood sugar. But Levels is marketing itself as a wellness product for anyone to use and isn’t making any diagnostic claims. “Levels is currently a general health and wellness program not intended to diagnose, manage, or treat any health conditions,” says Dr. Casey Means, the company’s co-founder and chief medical officer.

But let’s back up a little and talk about glucose itself.

You might think of glucose as the primary building block for energy inside your body. Your digestive process breaks down the foods you eat (especially the carbohydrates, but fats and proteins, too) and converts much of it into glucose, which it puts into your bloodstream. When that happens, your pancreas gets a signal to release insulin, which is a hormone that allows the cells in your body to take up the glucose and use it as energy (every cell in your body uses glucose).

The problem is that there can be too much of a good thing. When there’s too much glucose in your blood, it sort of overwhelms your system. Your muscles can’t take it all up, and bad things start to happen. It may get stored in fat cells as triglycerides. It may damage your liver, brain, and other systems. Big doses of glucose can also cause your pancreas to make too much insulin, which can lead to something known as “insulin resistance,” where your cells start ignoring the insulin and take up less and less glucose over time, which means more and more glucose stays in your blood. This can lead to a whole host of medical problems, including type-2 diabetes, heart disease, obesity, and potentially things like cancer, Alzheimer’s, reproductive issues, fatigue, brain fog, and much more. According to a 2018 study from UNC at Chapel Hill, only about 12 percent of Americans are metabolically healthy, which is a frighteningly low number.

This is all a fairly high-level breakdown. If you want to get into the nitty-gritty, Levels wrote what it calls its Ultimate Guide to Metabolic Fitness, which is a fascinating read and goes into more detail than I can here. The TL;DR version is this: High spikes in your glucose levels are bad, but every body is different, and there isn’t a one-size-fits-all solution that works for humans. What causes a spike in me may not cause a spike in you. We may all respond differently to the same exact foods, exercise, or sleep routines, and while some rules of thumb may hold somewhat constant, the only way to know for sure is to experiment and track the results, which finally brings us back to the thingy on my shoulder.

The disk that’s stuck to me is a continuous glucose monitor (CGM). These products themselves aren’t super new, and Levels doesn’t actually make this one. Instead, it works with a product called the Freestyle Libre, made by Abbott. The gadget accounts for much of the cost of the Levels program. Each one lasts for 14 days, so you have to swap them halfway through. The disk-shaped sensor comes embedded in a larger, round plastic stamp. You try to find an out-of-the-way spot on the back of your arm, ideally in the little pocket between your triceps and deltoid, and you clean the area with an included alcohol pad. Then, you put the stamp on your arm and depress it until you hear a loud click. In that click, the device actually sticks you with a little pin, which is instantly withdrawn and replaced with a little, flexible, quarter-inch thread, which is about the thickness of a single bristle on a hairbrush. Levels promises that it’s completely painless, and indeed it was. I literally could not feel it at all, either during or after.

Once you remove the plastic stamp, you’ve got this little white disk stuck to you. You slap the larger, black adhesive circle over it just to give it some added protection, and you’re good to go. It’s completely sweat-proof and waterproof (I ran, swam, surfed with it and never had any issues), and you’ll largely forget it’s there at all. The sensor logs a sample every minute and transfers all of the data over to your phone when you scan it. To do that, you simply touch the back of your phone to the sensor. It has an NFC radio, and it transfers all of the data points collected since your last scan over to the Levels app.

That app is where you spend most of your time. That’s where you log all of your food and exercise. You simply write in what you ate and when you ate it, or you can take a photo of it if that’s easier. You don’t need to be too specific (i.e., you’re not counting calories, ingredients, or macros); you just enter in enough information so you remember what you had. You can also log events like meditation, sex, or moments of acute stress. Whatever you want, really — you can see how your body responds. Levels recommends you keep your glucose levels between 70 and 110 mg/dL. The ADA says you can go up to 140 mg/dL, but once you cross the 140 line, you’re classified as “pre-diabetic,” so Levels wants you to stay well clear of that and in the “optimal” zone.

The name of the game is avoiding glucose spikes and dips. The app shows you a graph of all your data points, and you want to see a nice, smooth curve after meals. Levels also rates each logged item from zero to 10 (with 10 being the best), so you can easily interpret your results. I logged nearly everything I ate and every minute of exercise for a month, and I was genuinely surprised by the way my body responded to certain things. 

For instance, there’s this one protein bar that I’ve been eating for years that is high-protein and low carbohydrate, etc. I was shocked that it made my glucose spike aggressively. Levels gave it a 2. It turns out that my body doesn’t mind some sugar alcohols, but other types of sugar alcohols cause a strong reaction. Thankfully, my regular breakfast of eggs with salad and coffee came in at a 10, but if I added a bowl of oatmeal to it, my score dropped down to a 3. Chicken tenders were fine with a savory barbecue sauce, but if I switched to my favorite (a sweet one), it dropped all the way down to a 0. Damn. Potatoes seemed to be one of the worst offenders for causing me spikes, which was heartbreaking, but sweet potato fries were less bad.

One of the biggest takeaways for me was how I could mitigate the negative impact of one thing by adding something else. For example, instead of eating that protein bar that gave me a 2 by itself, if I ate it with some jerky and almonds, it got upgraded to a 6. Dinner would frequently cause me to spike, but dinner with a walk immediately afterward improved my numbers significantly because my muscles used up some of that excess glucose in my blood. A cocktail then going to bed was bad, but a cocktail then going to bed with someone else… not so bad! You’re also given a score for each day and week as a whole, from 0 to 100, with 100 being the best.

Levels suggests you don’t make any changes during the first week, so you can see what happens with your normal habits. For weeks two and three, they suggest you start experimenting with different foods to see how your body responds to different things. For week four, it’s recommended that you try to implement your learnings and go for the lowest score possible. Everything you log takes about two hours before you can see your score (because your body doesn’t respond to food or exercise immediately), but then you can see everything in the app. Levels also emails you daily and weekly reports and, finally, one big report at the end of your one-month journey that has 14 pages of granular info broken down into easy-to-understand charts and graphs.

While the device itself doesn’t hurt at all, it must be said that there are some pain points. For starters, Levels is currently using a two-app solution. You have to download the sensor’s app (called LibreLink) and set up an account on it; then, you tell that app to share info with the Levels app. Once everything is set up and linked, you don’t really need to deal with LibreLink again, but Levels acknowledges that the onboarding process isn’t ideal, and it’s working on a better solution. 

A larger issue is that the sensor itself can only store eight hours’ worth of data points. That means that if you don’t remember to scan it right before you go to bed and again right when you wake up, then you’ll have some gaps in your data. Not ideal, especially if you’re one of those lucky people who actually gets eight-plus hours of sleep (tell me what it’s like?). Levels is working on compatibility with another continuous glucose monitor that has Bluetooth so it could constantly push updates to your phone in the background, but no word yet on if or when that option will be available. 

Levels could go further in clarifying what your numbers mean, especially toward the beginning. Right now, the way the app is set up, you don’t get a ton of information or advice to go along with your data. The company has written a lot of blogs that help explain the ins and outs of the science behind this, but it would be nice if it were better integrated into the app and if there was more built-in coaching as you went. 

Lastly, there’s the price. $400 for a month is steep. For that, you could buy a very solid multisport watch with GPS (or an Apple Watch) that would last you for years and track a ton of different metrics and activities. Of course, the data you get from Levels is unique in the pantheon of fitness trackers, but it would be easier to take the leap if the cost wasn’t so exorbitant. Its price certainly supports the argument that fitness tech really only benefits the wealthy.

Ultimately, I enjoyed my experience with Levels, and I can see it being a useful tool for athletes who want to learn how to fuel properly for their unique body chemistry and for people who have concerns about their metabolic fitness. I didn’t lose any weight in the month I did it, but that’s because glucose levels are just one part of the picture. Levels works with Apple Health and Google Fit to automatically import activities, but part of me thought it would be nice if it could integrate with a calorie tracking system like MyFitnessPal.

After some thought, though, I came around to believe that it might be best to take a month to simply learn how your body responds to different foods and activities and then integrate those learnings into your diet and exercise plan going forward. That’s something I’m already doing in the days since I took the tracker off. Where I used to just snack on an apple, now I’m more likely to pair it with some yogurt or cheese because I know it won’t spike my glucose as much, which will be better for my long-term health and may help prevent an energy crash a few hours later. That really is valuable.

Levels is targeting a full launch sometime in 2022. It’s currently in a semi-closed beta, and it has more than 100,000 people on the waiting list, but if you use this link, you should be able to skip the line, and most people will get their tracker kit within two weeks of ordering.

Update, 3:50PM ET November 30th, 2021: After this review was published, Levels reached out to say that it is now planning its full launch in 2022 instead of by the end of this year, though it doesn’t have a more precise time frame than that. We’ve updated the article to reflect this information.

Photography by Brent Rose for The Verge