Alexandre Bensimon

Quantified self


Behind this seemingly complicated term, lies a rather simple concept: we can gather and analyze data from our body and behavior to find ways to improve ourselves. We often talk about health related data such as the quantity and quality of sleep but it’s actually a broader concept. For example, some people precisely track how they spend their time each day in order to improve their productivity and live more efficiently.

The main idea is that you usually need to measure something in order to improve it. How we feel about something is not always a good indication of how the thing really is. Let's say you want to lose weight (how original). It's tempting to think that eating until you "feel full" is enough and that the "body knows how to regulate itself". If this were true, people wouldn’t be overweight so obviously something else is going on here. I’ve already written about how our bodies have not evolved to deal with modern society and how we have found ways to hack our cravings. You'd better get ideas like "I feel good when I do/eat/read/think this so it's got to be good for me" out of your head or you’re going to get in a lot of trouble. If we accept the fact that we cannot trust our own instinct, we have to use tangible and objective data to be able to make better decisions. As David Sinclair says: "You wouldn't drive a car without a dashboard so why do we do that for our bodies which are even more important".

Vision for the future

We should differentiate between chronological age (since when we were born) and biological age (estimation of your health and fitness levels using multiple biomarkers). Some people already have a great knowledge of a lot of their biomarkers and how to improve them, which requires the right doctors and expensive care. Hopefully, it will become cheaper in the future.

Two main advantages of the quantified self on health are personalization and prevention. At the moment, the health sector is generalized: you consume food and pills that are mass produced. This is mainly a cost problem: collecting data on yourself and getting personalized healthcare are currently both expensive. In the future, we can imagine that instead of going to the lab to get a blood test, we could have personal sensors that collect and analyze blood at home. Based on the results we could receive daily deliveries of food and pills made for our precise needs.

Although we’re making progress on the prevention side, most people currently live their life in a reactive way. We go to the doctor when we feel sick and we don’t really mind what we eat before getting unhealthy. For cancer, we know that the earlier we find a tumor, the more chance of survival we have. By regularly measuring our biomarkers, this knowledge could be analyzed by AI models to detect early signs of disease and course-correct immediately.

Women can already use ovulation periods and other related data as a birth-control method instead of a hormonal method. Hormones are a big subject for women and men alike. Hopefully we’ll be able to get interesting data to help fix hormone imbalances.

Consumer products and sensors are improving every year. In the future, we won’t have to charge them or even think about them, they’ll just collect data automatically and give us advice and warnings to improve.

The next really interesting frontier will be the brain. The company Kernel is working on a headset that could read and analyze our neurological patterns. We could quantify when we’re the most receptive to learning, how meditation affects our brain, the evolution of our mood throughout the day or better understand and treat depression.

What can we do right now?

The future looks bright but there are already great products available today that we can use:


These are currently the most common and simple to use. Most of them can track your heart rate pattern (useful for exercise, meditation and stress mitigation) and your sleep (quantity and quality). Some can even track your blood oxygen or the sound level in your environment so that you know if you are exposed to volumes that are too loud.

We can split them in three categories:

  • Smartwatch: this includes the watches from Apple, Samsung, Huawei and many others. This kind of watch integrates best with your smartphone ecosystem and is more focused on lifestyle and customization. You can usually use the watch to call, send messages, get directions, and do a lot of things you can do with your phone.
  • Sport watch: This category is dominated by Garmin. I put it in a different category because these are usually more bulky and the target audience is people doing more intense exercise or outside sports like trekking or rafting.
  • Fitness tracker: These are usually more minimalistic. This includes fitbit bands, Whoop, the Oura ring, etc. Most of the time it has a very basic screen or no screen at all so you usually forget about it and you use your phone to see the data.

If you want to stay updated and compare wearables, The Quantified Scientist does in-depth testing and analysis of many wearables.

Sleep specific

If you don’t like to wear a watch or a ring while you sleep, there are other good options for sleep tracking, from sleeping mats to smart mattresses.


This is the most complex to track right now. Some people log everything they eat in apps like MyFitnessPal so they can precisely know their macro and micro nutrients levels.

Continuous glucose monitors can track the amount of glucose in your blood to understand what type of foods have the worst effect on you. Of course we don’t need a CGM to know that eating a cookie will spike our blood glucose, but some people react differently to potatoes, rice and bananas for exemple. CGMs are still mainly used by people who have diabetes but some brands are trying to make them mainstream.

Body composition

Knowing your height and weight (BMI) is not enough to know if you’re healthy. Some people are in the “overweight” category but because of the muscle weight. And the “healthy” range is too broad to give interesting information on your fitness level. You actually need to know how much muscle and fat percentage you have. Using some kind of smart scale can give you much more information than a regular scale.

Air quality

When we think of pollution we often think of cities with old cars and no trees. But actually, the air inside your room can get polluted really quickly if you don’t get fresh air in. Some sensors can help you know when the air quality is bad and other products can automatically purify the air.