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Is InsideTracker Worth It? A Dietitian’s Review

Can tracking what is going on inside your body make you a better athlete? Registered Dietitian Matthew Kadey reviews InsideTracker, the popular app that promises to help you hack your health.


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The past few years have been quite the time for athletes who want to arm themselves with the knowledge necessary to optimize their health and performance through tweaks in their diet and lifestyle. While the endurance crowd has for decades been measuring various athletic metrics: heart rate, split times, VO2 max, the mostly aimless lactate threshold, and so on, only in recent times has the ability to analyze what is going on inside your body leaped to new heights. Case in point: InsideTracker, the blood screening service that seems to be on just about every endurance athlete’s Instagram account these days.

It used to be that you could only get specialized health tests on a doctor’s orders. Now a new wave of bio-wellness companies are encouraging us to send them our blood, saliva, urine and even poop to their web- and app-based platforms. From there, algorithms can spit out numbers to help athletes zero in on ways to fine-tune diet and fitness (or so they claim). This shift from outpatient to at-home testing is thanks to advances in sample collection.

Think of it as a personal touch to better understand what is going on in our bodies that, in theory, can lead to performance and health breakthroughs. The pros and biohackers are seemingly always waxing poetically about DNA testing, smart patches and glucose monitoring on social media which, in turn, has made athletes of all stripes a lot more interested in geeking out on their own data.

A handful of companies, including Viomewill take a look at your microbiome via an at-home stool test you mail them and then they make individualized food and supplement recommendations geared at optimizing your microbiota. Continuous glucose monitoring (CGM) allows athletes to track their blood glucose throughout the day and during training to better understand how to fuel properly. Lumen measures your metabolism by calculating the carbon dioxide concentration in your breath so you know whether you’re burning mostly fat or mostly carbs. Instead of peeing in a cup at the doctor’s office, you can pee on a Vessel test strip for essential health metrics like stress, hydration, and nutrient levels. To take the guesswork out of hydration, grab yourself a Gatorade Gx Sweat Patch, a one-time-use adhesive that tracks sweat rate and the amount of sodium lost through sweat.

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What is InsideTracker?

In line with at-home performance testing came InsideTracker. Positioned as a personalized performance and nutrition system, it’s a blood-testing company that measures up to 43 biomarkers to provide personalized insights based on everything from cholesterol to vitamin D to immune cells to liver enzymes to stress indicators. Tack on the DNA test to see how 261 genetic markers influence your athletic and longevity potential.

The company states that their algorithms, based on the latest research, determine which biomarkers you’ve already optimized and flag problem areas to deliver users custom interventions—“eat more iron-rich foods” or “aim for a few more hours of sleep each week”—that can help you level up. Some of the things they test for are indeed areas of concern for endurance athletes: Inadequate vitamin D and calcium levels could raise the risk for stress fractures, and low vitamin B12 levels can compromise endurance and make it feel like you are running through Jell-O. Immune/stress markers that are off-kilter can be a sign of overtraining and inadequate fueling.

There is a level of analysis based on age, gender, ethnicity, activity level, the amount of alcohol consumed and other factors beyond what most of us can expect from a visit to the doctor’s office. The company has partnered with Garmin to integrate sleep and heart rate data into its results, so it can deliver even more personalized daily tips.

Marathon legend Shalane Flanagan credits the personalized blood-level monitoring that InsideTracker provides with helping her crush Project Eclipse—completing six marathons in under seven weeks with an average run time of 2:38:30. From this, she gleaned important biometrics which informed her training and nutrition. For instance, her first blood result revealed “suboptimal” vitamin B12, something that likely would not come to light from a standard doctor-issued blood test. B12 aids in the formation of red blood cells and energy production, which will impact the way you feel in training and on race day. One post-marathon blood analysis showed elevated liver- and muscle-breakdown markers, along with increased inflammation and white blood cells, which is the information she needed to bring about big changes to her training, traveling, and fueling.

This study in the journal Scientific Reports found that users of the InsideTracker platform were able to improve upon 14 of 17 biomarkers that are most often problem areas in the general population, including blood sugar, iron, vitamin D, testosterone and cholesterol. This is arguably an important step towards validation of their automated algorithm to churn out effective personalized and actionable nutrition and lifestyle recommendations.

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Does InsideTracker Work for Athletes?

After a trip to the lab (at-home blood draws are also available) to suck out a few vials of red fluid, my blood panel was a mixed bag of A-OK and Let’s get real here.

InsideTracker’s slick interface that is designed to translate mysterious numbers into a clearer picture of your health displays a series of color-coded, user-friendly charts: red zone for levels that a deemed too high or low, yellow if you’re in the “needs work” zone, and green for optimal levels based on individual needs. Sleep, stress, dietary preferences and allergies, fitness habits, meditation and supplement regimens are all taken into account by their engine prior to generating ultra-personalized recommendations based on the blood work. So a hard-charging triathlete will have an “optimal” ferritin (iron storage) that is higher than a couch potato. That’s a good thing, as many health and fitness apps are not designed for the active population, which can have different physiological markers. (If you’re an endurance athlete who has ever been told your heart rate or blood pressure is alarmingly low, you know this to be true.)

One particular area of concern for athletes is Vitamin D, and InsideTracker flagged vitamin D as a glaring area of concern in my case.

A screenshot of InsideTracker used in this review of InsideTracker for endurance athletes

Vitamin D is crucial because it plays a big role in your immune and bone health, and apparently so much more including improving exercise capacity. The National Institutes of Health says that a level anywhere between 20 nanograms/milliliter and 50 ng/mL is considered adequate for healthy people, whereas InsideTracker says my optimal zone is between 32 and 100 ng/ml. Mine was 22 ng/mL, in the red zone and close enough to the NIH’s cutoff level that I decided to follow InsideTracker’s recommendation to boost my daily supplement dose. Even though I was popping 1,000 IU of vitamin D daily and going big on vitamin D-rich canned sardines at lunch, it wasn’t nearly enough to get my levels in the optimal zone amid the dank Canadian winter. My partner was using vitamin D supplementation more liberally and tested for better levels. The suggestion to spend 20 minutes a day in the sun to make more vitamin D will have to wait a few more weeks up here in the great white north.

RELATED: Everything Endurance Athletes Need to Know About Vitamin D

When a biomarker like vitamin D or LDL cholesterol is found to be less than optimal and there is a dietary measure that can be taken to increase or decrease levels as needed, InsideTracker provides a set of foods and a personalized food list that can help get you where you need to be. In the case of vitamin D, I can add more halibut, carp, sockeye salmon, maitake mushrooms and pork shoulder to my life. Perhaps popping an extra capsule is an easier option as my local grocer is lacking in maitake fungi. They also do recommend I consult with my physician to discuss the results—also great advice, as athletes should consult with their physician regularly anyway.

A screenshot from an InsideTracker review
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InsideTracker review: What We Liked

It’s nice to see that InsideTracker seems to take a food-first approach where possible to ameliorate problem areas. One of the few bio-wellness companies not hawking supplements.

If you have three or more tests in your InsideTracker profile (taken by them or your doctor), they provide a “trendline graph” on your bloodwork page. So by putting my present and past results on one graph, it would reveal how my vitamin D biomarker has changed over time, for better or worse.

The service does not intend to find disease, so users with any serious blood results like off-the-chart blood sugar or cholesterol levels would not be told whether they may have diabetes or cardiovascular disease, but instead would be advised to visit the doctor.

It was morbidly fascinating to browse the data and see, specifically, that my LDL cholesterol was 154 mg/dL. That is 58 mg/dL above what their algorithm says is the upper end of my optimal zone for good health. Ouch! Despite some of the rhetoric, high LDL numbers should still be considered problematic for long-term heart health as it encourages the build-up of plaque in our arteries, causing them to narrow and constrict blood flow.

For this, I embrace the recommendation from the company’s in-house dietitan to sneak more soluble fiber into my menu to help bring the LDL numbers down towards the green. In particular, I’m spooning up a psyllium gel (a gloopy mixture of psyllium husk and water) a couple of times a day, a proven way to improve the lipid score). I already don’t eat much in the way of saturated fat from meats and coconut oil, which plays a bitter role in cholesterol numbers than does dietary cholesterol. But still, I’m also paring back my daily egg habit.

I’m pleased to report that the biomarkers in my sugar, testosterone, inflammation, micronutrient, liver, and stress groups did not present numbers requiring action.  These include several biomarkers that InsideTracker looks at that are not typically tested by a physician unless there’s a concern. For example, the service measures your levels of vitamin B12 and magnesium, which can be nutrients of concern depending on dietary choices, and an enzyme called creatine kinase, which can be a marker of muscle degradation due to overtraining.

And what if a simple blood test revealed how fast you’re aging? Bingo. Using an algorithm well beyond my skill set that mines the leading scientific literature on longevity and nutrition, and compares that aggregate data against your own, InsideTracker determined that despite my birth certificate saying that I’m 47, my InnerAge is a satisfying 38.5. My average blood sugar (HB1Ac), white blood cell numbers, and albumin (serum protein) count are all apparently helping me beat the biological clock.

A screenshot from InsideTracker review

Their DNA testing is not available to us Canadians, so I’ll have to wait and see how my genes might be impacting my athletic potential, body weight, sleep patterns and bone health. Blood [plus] DNA can be a powerful one-two punch for generating personalized guidance.

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InsideTracker review: A word of caution

Without question your blood, DNA and lifestyle habits are a goldmine of data. Together, they can inform you about what’s going right, and what’s needs improvement. I’ll be quick to say that using InsideTracker gave me plenty of data that resulted in actionable modifications in the way I eat and supplement.

From monitoring your blood biomarkers to sweat rates, if any of these testing platforms help you find a system that allows you to more effectively manage your health and fitness, that’s great. For many people, it can be the push they need to better engage in their nutrition and lifestyle.

But data-driven health apps can have their limitations and raise a few red flags.

While knowledge is power, it’s easy to get overwhelmed by all the data. Whichever programs you are using it’s vital to have a professional help you interpret your data so that you make the appropriate decisions. A slightly low testosterone level should not automatically send you hunting for T-boosters on the dark web. A respiratory infection during the blood test may have sent your white blood cells crashing, and thus not a good indicator that your immune system is out-of-whack. When a program spits out data on your personalized microbiome using an app, lining up for a tub of probiotic pills may not be the answer.

There is always the risk that some people may interpret their results incorrectly and think they are in big trouble when in fact their numbers just reveal that a little improvement is necessary, not that huge nutrition or lifestyle change are required. Blood sugar or cholesterol levels outside the “optimal” zone should not necessarily be interpreted as danger, danger. There is a dearth of research to show that raising your magnesium level from 1.9mg/dL to a more optimal 2.5 mg/dL level has an appreciable impact on long-term health. Glucose monitoring may lead someone to assume that bacon is healthier than an apple based on the reality that the latter will raise blood sugar more than will slices of cured pork.

In general, such services have the risk of leading to anxiety, and potentially needless costs for treatments. The emotional stress from being obsessively preoccupied with your health can be just as damaging as would higher than desired pro-inflammatory CRP levels.

Sometimes the sales pitch is outpacing the science. Designing personalized nutrition advice based on microbiome results is still far from a perfected science. Home tests for food sensitivities and intolerances are fraught with misleading results that could lead someone to needlessly bid adieu to their favorite foods. And how much trust you want to place in the algorithm is ultimately up to you. Be sure to look into the background of the company and make sure serious scientists who aren’t fond of pseudoscience are part of their portfolio. Right now, it’s up to the companies to validate their devices and services. So some vetting before investing is a wise move.

And what if these discourage people from seeing their doctor, thus missing red flags that can indicate the onset of a disease? No algorithm or pee strip can make up for a one-on-one visit with the doctor for a clearer picture of your overall well-being. Please, don’t make any medical decisions based on an at-home test.

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InsideTracker review: The bottom line

No amount of bio-tech and biomarkers are going to be a shortcut to health and performance optimization. Instead, look at services like InsideTracker as another tool in your arsenal to help boost awareness and be all that you can be. It’s what appropriate measures you take using the information that’s going to potentially add healthy years to your life and seconds off your split times. (Which reminds me, I forget to take my vitamin D—again.)