Health Data Overload
The Perils of An Over-Reliance on External Health Data
There are over 1 billion connected wearables and hundreds of millions of health app users across the globe. When you consider that wearable tech and health metric tracking is still in its infancy, that is a staggering rate and level of adoption. And the scope of what we can track has increased dramatically in the last decade. Now, not only can you get notifications on your wrist, you can track steps, heart rate, calories burned, blood oxygen, respiration rate, various sleep metrics, or some combination of all of the above for general wellness, readiness, or recovery scores. Through apps like MyFitnessPal or Lose It!, you can track calories, macros, micros, water intake, etc.
The ability to track all of this stuff is unequivocally cool, and collecting feedback on vital health metrics has the potential to do a ton of good. But in my opinion, health data is only as good as its ability to improve future behavior and detect health emergencies. If it doesn’t achieve either of those ends, it’s a distraction at best and harmful at worst.
As someone that considers himself very tech-forward, don’t mistake my apprehension for obstinacy. But with many of these metrics, I can’t help but think of the quote from Jeff Goldblum’s character Dr. Malcolm in Jurassic Park:
Your scientists were so preoccupied with whether they could, they didn’t stop to think if they should.
My opinion on this, as with most things, is nuanced. So I will outline the pitfalls of tracking everything under the sun, but also give some practical recommendations for which metrics I believe are genuinely worth a damn.
Just Because You CAN Track Something Doesn’t Mean You Should
Knowledge is power, right? Well, not always. Human beings have lived for thousands of years without needing to track every body process. Our bodies are pretty damn good at taking care of what needs to be taken care of. Take this new trend of continuous glucose monitoring (CGMs), for instance. Unless you're diabetic or believe yourself to be pre-diabetic—in which case you should talk to a doctor about that—there is little need to know what is going on with your blood sugar. It will go up and it will come back down and vice versa, and the extent to which foods affect that matters little in the short-term unless it affects how you feel. But if that's the case, you don't need data to tell you that.
Which brings me to the main drawback with many of these metrics. Data is great if it positively informs choices, but not great when it makes you think you have a problem when you don't.
A Lot of Health Data Is A Nocebo-In-Waiting
A nocebo effect is when negative expectations or beliefs about something—in this context it's the data you collect—can actually manifest negative outcomes. If you have a poor sleep score, you may more strongly feel the effects of sleep deprivation. If your heart rate is higher than you expect, it may make you anxious and perpetuate the problem. You might see a spike in blood sugar that is way higher than normal and assume something is wrong. For any of these metrics, you might mistakenly see a signal in the noise, aka pareidolia.
When you take internal, automatic processes and try to control them, you not only make the task of managing your health vastly more complicated, you could be trying to fix something that isn't broken. The longer I've been in a health-related field, the more I understand the role that beliefs play on wellbeing and recovery. I'm not advocating sticking your head in the sand; after all, many of these metrics give us helpful insight that may improve wellbeing or performance. But a more simplified approach would be more effective for a large majority of the population.
Health Data Tracking Is Like Always On GPS
GPS has become indispensable for me. All I need is the name of a place and I can get to it. Long gone are the days of freaking out over missed turns. They are without a doubt a net positive. But...the part of our brains that maps out routes and directions in our heads is virtually non-existent now. Who needs to memorize shortcuts or visualize how roads connect to one another when you can just fire up Google maps?
Much of our success when it comes to health outcomes is predicated on our ability to engage and improve healthy habits and behaviors and to key in on internal mechanisms or cues. Those softer skills atrophy when you rely too heavily on external data and we lose a lot of the why behind our actions. Constantly relying on external data to validate healthy behaviors can lead to some unfortunate side effects.
Goodhart’s Law
Goodhart's Law states that when a metric becomes the goal, it ceases to be a good metric. For example, macro tracking is often used to ensure that someone achieves healthy long-term weight loss, but in an effort to perfectly hit their macros, some folks might employ some strange dietary choices (love Dr. Mike but this is bizarre) or eating behaviors. It becomes more about hitting the numbers instead of achieving a sustainable and healthy diet. I see the same type of thing in strength training. How much weight you move is the proxy metric for strength, but once people lose the original intent and chase numbers, you get this insanity.
As a recovering Apple Watch user, the impetus to close your rings can be so overwhelming that people will ask questions like this. You could claim that it's not the data's problem that people abuse it, but it does highlight the obsession data tracking like this can induce in people. The lesson here is to maintain some level of detachment from the data and to realize that it's a means to an end and not the end itself.
My Favorite Metrics
This is the shortlist of metrics that I think provide the most bang for your buck, so in other words, they are the simplest to track and net you the most benefit.
Steps
Although tracking steps is limiting in some ways, there is pretty good evidence that step count is correlated with all-cause mortality. And because it's unlikely that anyone can intuitively guess how many steps they're getting, a step tracker is probably a wise investment. Based on the study included, protection against all-cause mortality level off around 6-7,000 steps for adults 60 and older and between 8-10,000 steps for adults under 60. But this largely ignores individual differences and more steps may have additional benefits for other fitness goals. Regardless, aiming to improve your step count is probably a worthwhile aim for folks looking to improve their health or manage their weight.
Calories
I believe people can lose weight without tracking calories, but I also believe it's more difficult. People often draw on the argument that humans haven't needed to track calories to stay lean in the past, but we also had a much more forgiving food environment. If we hearken back to our hunter-gatherer days, food was so scarce that we needed to eat everything we could to survive. Now, calorie-dense food is abundant, which means we need a different approach to managing intake to prevent excess weight gain.
Since energy balance is the ultimate determinant of long-term changes in body weight, calories are the most important metric for achieving a healthy body weight, at least on the energy-in side of the equation. You have many options for calorie-tracking, and each one has different strengths and weaknesses. Examples include MyFitnessPal, LoseIt, MacroFactor, and MyNetDiary.
Protein
I don't believe meticulous tracking of protein is necessary beyond ensuring you're getting enough to support muscle growth or maintenance. Most sources show a range of 0.6-0.8g/lb of bodyweight to be sufficient for most people. Women that don't lift may be able to get away with the lower end of this range and men starting a lifting program might want to err on the higher side of the range.
Weight/BMI
Weight has received some heat in recent years due to its crudeness, volatility and the fact that people often attach their sense of self-worth to it. But it still remains one of the most accessible metrics for monitoring our health. BMI, which represents the relationship between your height and weight, is criticized for similar reasons.
But here’s the thing…for the large majority of the population, especially the non-lifting population, BMI and weight are good, low-cost proxies for health. There is a J-shaped relationship between BMI and all-cause mortality, which basically means that we see an increase in all-cause mortality at the very low end of BMI (<20) and then more or less linearly above a BMI of 25. However, the increased mortality risk of BMI lower than 20 may be confounded by pre-existing disease states or eating disorders.
Heart Rate
I don't personally get much use out of measuring my heart rate, but it can be useful as a proxy for intensity. It's also helpful for folks that need to ensure they're staying in a particular zone for cardiovascular training.
It may also be useful to detect arrhythmias or when your heart rate ventures wildly out of your normal zone (tachycardia and bradycardia).
Least Useful Metrics
Continuous Glucose Monitoring For Non-Diabetics
I will start by saying I think it's generally a good idea to eat foods mostly low on the glycemic index. Much of the positive effect of low GI foods may be attributed to a concomitant reduction in body weight, but they may have benefits that extend beyond weight reduction for obese individuals.
In any case, if we're specifically talking about non-diabetic folks and the need to continuously monitor blood glucose, well, I think it's unnecessary. Knowing acute blood sugar changes is as useful as knowing whether you're primarily burning fat or carbs during your workout as someone trying to lose weight. Your ability (or lack thereof) to manage your blood sugar, just as with fat loss, is about behaviors over a long period, not what is happening at any given moment.
I think continuously monitoring blood sugar would lead to the same problem as folks that place way too much emphasis on daily weight fluctuations. They lose sight of the bigger picture. Focus on the eating behaviors and better foods and your body will take care of the rest.
Blood Oxygen For Folks Without Respiratory Issues
Most of the utility of blood oxygen sensors lies in their ability to detect marked drops in oxygen saturation in people with chronic respiratory diseases or conditions in which respiratory function is impaired. Unless that’s you, you likely don’t need to constantly monitor blood oxygen. For starters, oxygen sensors on wearables aren’t accurate all the time. And more importantly, a large majority of people will see little to no fluctuation in oxygen saturation, with most hovering in the range of 95-100%. If you want to marvel at your respiratory prowess, knock yourself out; otherwise, it’s just more noise.
Calories Burned During Exercise Bouts
Not only do these values have a tendency to be wildly inaccurate, they seem to exist solely to give people permission to eat more. For starters, don't do that. Every equation used to determine maintenance calories already has an activity modifier built in. I don't know if MyFitnessPal still does it, but it used to add exercise calories onto your target by default, which makes no sense. If the activity modifier is already built in to your caloric target—it almost always is—treat any extra calories burned during the day like an added buffer to help you stay on track.
I have another problem with this metric that's more philosophical in nature. I don't like people viewing exercise solely through its utility as a calorie-burner. Exercise has myriad of physical, cognitive, and psychological benefits. It also kinda sucks at burning calories. Bottom line, you should exercise because it's also good for you and not simply because it "burns calories".
“Jury Is Still Out” Metrics
Sleep Scores
Most of the problems that I have with sleep scores isn’t the data itself, but rather how people choose to interpret or act on it. I actually think getting feedback on your sleep can be valuable. For instance, you may notice that your sleep sucks after a night of drinking or staring at your phone before bed. But I also think the feedback can be self-fulfilling or act as nocebo (there's that word again). If you wake up and feel fine, but notice that your sleep score sucks, how do you think that will affect your day? For some it may not be a problem, but I have a suspicion that it may ruin others.
Aside from the fact that I don't love wearing anything in bed, I noticed there wasn't always a direct correlation between my sleep score and how I felt. That doesn't mean the information isn't useful or accurate, but it was affecting my energy levels and actions in mostly subconscious and negative ways. If people do track sleep, I think a small, unobtrusive device that doesn't blast you with a readout upon waking is a good compromise, like the Whoop. But always remember to take the information with a grain of salt and not to let it ruin your day.
Recovery Scores
Similar to the sleep score, my beef lies mostly in what people do with these. If it's accurate—I don't know how to determine this—maybe it can help inform choices, but I don't think we need to be a slave to data, especially if it doesn't line up with how we feel. Many folks, for instance, may use it as an excuse to not train or to dial back when they would have been just fine doing their regularly scheduled programming.
Water Intake
I know that you’re probably thinking “you can pry my Stanley from my cold dead hands”, but hear me out. Drinking water is obviously important. We need it to survive, and unlike food, we can’t go very long without it. But most people drastically overestimate the need to micromanage their water intake.
There are some circumstances like exercising, being in a warmer climate, being pregnant or breastfeeding, when you’re sick and losing fluids through vomiting and diarrhea, etc. where you may need to up your fluid intake. But lots of people, especially if you don’t meet any of the aforementioned conditions, can drink to thirst.
We get water from the food that we eat, especially if we eat lots of fruits and veggies, as well as any other beverages that aren’t water, like coffee, tea, milk, orange juice, etc. And thirst, like hunger, is a useful biological mechanism that drives us to get what we need.
So don’t let me stop you from drinking gallons of water every day, but the only thing you’re realistically increasing is your number of steps to and from the bathroom.
Summary
I do believe data can be useful. After all, if we don't know what's happening, it's hard to know when or where we need to make changes. Data that can help you move more, eat less, recover better, watch out for emergencies, or remind you to chill out can help you navigate our new uncharted modern world. But it's very easy to get overwhelmed. I think most people should adopt a "less is more" approach to this stuff. Only track something if you genuinely think the feedback will help you improve your life. Don't do it just because you can.