Posts in Wellness

What I Learned by Wearing a Continuous Glucose Monitor (CGM)

For the past 14 days, I’ve been wearing a continuous glucose monitor (CGM) while testing every possible food I normally do and don’t eat combined with different types of physical behavior.

I learned a lot and changed my already over-optimized diet as a result.

What is a CGM?

As the name suggests, it’s a system made of a sensor and a reader/smartphone app that continuously measures your blood sugar throughout the day and night.

It’s mostly used by diabetics, but with the recent rise of both, a number of startups promoting CGM use, and overall wellness awareness (pandemic silver lining), it has become rather popular among non-diabetics as well.

Why would non-diabetics use CGM?

As Dr. Peter Attia (@PeterAttiaMD) mentioned in his recent AMA episode, higher glucose variability and higher peak glucose levels are associated with accelerated onset of disease and death, even in non-diabetics. Studies show that higher glucose variability in non-diabetics is associated with an increased risk of cardiovascular and Alzheimer’s diseases, cardiovascular death, frailty, cancer death, and all-cause mortality compared to lower glucose variability. And CGM provides almost instant metabolic data so you can make changes in your diet and lifestyle to reduce the likelihood of a surprise diagnosis later in life.

Given my obsessions with health and data, I ordered the Abbot FreeStyle Libre CGM as soon as I got to a country that allowed me to do that without a doctor’s prescription. If you’re in the US, you can use Levels – they use the same Abbot device but pair it with their great app for more insight into your metabolic health.

The system is incredibly easy to use. Apply the sensor to the back of your arm (it doesn’t hurt, I promise), download the app (or buy a separate reader if your phone doesn’t have an NFC chip), pair them, wait a few hours for a sensor to calibrate (mine took almost 24 hours to calibrate properly, keep that in mind), and you’re good to go. Each sensor lasts only 14 days, so if you want to use it for recommended 28 days, you’d need to order two of them.

It is recommended to maintain glucose levels between 72–110 mg/dL (4.0–6.1 mmol/L), limiting post-meal glucose rises to less than 30 mg/dL (1.8 mmol/L) from pre-meal levels, and maintaining average glucose of 100 mg/dL (5.5 mmol/L) or lower.

Over two weeks, I managed to keep my average at 4.7 mmol/L (85 mg/dL):

Average Glucose Levels – Continuous Glucose Monitor


While staying in the target range 68% of the time, which isn’t too bad given that I intentionally experimented quite a lot.

Time in target range – Continuous Glucose Monitor

My estimated hemoglobin A1c was 4.6%, which is almost perfect.

Hemoglobin A1c – Continuous Glucose Monitor

I say “almost,” because based on this observational 2011 study that found a continuous increase in the associated risk for all-cause death throughout a broad range of hemoglobin A1c values, I’d prefer to keep my HbA1c below 4.5, even though based on the adjusted HRs and this study, anything below 5.0 seems to be good enough.

Crude incidence rates and adjusted HRs for all-cause mortality according to category of baseline glycated haemoglobin

As you can see, at hemoglobin A1c <4.5, there are only 5.7 all-cause deaths per 1000 person-years, with an absolutely dramatic increase to 24.5 deaths at ≥6.5 HbA1c.

Over the course of these two weeks, I kept a journal where I documented most of the meals and glucose readings.

Glucose Log – CGM

Some of the results were expected—yes, most foods with a high glycemic index will spike your glucose—but there were quite a few things that surprised me and changed my behavior as a result.

1. Not all fruits are the same.

I’ve heard lots of conflicting opinions about fruits. Even though I love fruits and never felt a sugar rush no matter how much I’d eat, it was interesting to see that some fruits which are considered to be the “good” ones would spike my blood sugar, but it would stay within the normal range after eating some other, supposedly the “bad” ones.

Fruits that spiked my glucose: cherries (8.4 mmol/L / 155 mg/dL after eating only 150g, even though its glycemic index is only 20), oranges, apples, strawberries, apricots, grapes.

Fruits that didn’t have as much effect, keeping my blood sugar within the normal range: bananas, pomegranate, raspberries, blueberries.

Behavioral change: eliminate all fruits that significantly elevate my glucose levels from my diet, keep eating the ones that don’t.

2. Almost any type of pasta is bad.

I’ve tested the wheat flour, rice, egg, and buckwheat pasta. The only one that didn’t spike the blood sugar as much was the soba made from buckwheat, which isn’t surprising given that it has the lowest glycemic index (56) of all.

Behavioral change: I used to have a side of pasta with my standard Mediterranean roasted vegetables at dinner, now I either have soba or don’t add it at all.

3. Rice has the worst effect on my blood sugar.

Yes, given its glycemic index of ~70, it shouldn’t surprise me as much, but no matter what type of other food I’ve tried during these two weeks—pastries, candies, pasta, cake—nothing could compare to what rice did to my glucose levels: it increased it to the record 10.7 mmol/L or 193 mg/dL!

Glucose spike after eating rice.

Behavioral change: forever eliminate rice from my diet.

4. Wheat flour in any shape or form causes the longest blood sugar spikes.

I’ve already mentioned the terrible effects of pasta and rice, but products made of wheat flour—bread, pizza, cakes, wraps, cookies, pastries, bagels, etc.—take the first place for the glucose surge duration.

For example, the glucose levels would go back to normal only 20 minutes after the 40% increase caused by cherries, but it’d stay up for 1.5 hours (!) after eating the wheat flour sugar-free pastry.

What about whole-grain foods? Unfortunately, there was no difference.

Behavioral change: I stopped eating bread roughly six years ago, but now I’ve also removed all other types of wheat flour foods, even the supposedly “healthy” salmon or vegetable wraps.

5. A 30-minute walk normalizes glucose levels.

One interesting find was that a 30-minute walk could significantly lower both the peak and the duration of the blood sugar spike. It turns out that muscle contraction when you exercise is an effective mechanism that absorbs glucose without the corresponding rise in insulin. And you don’t have to exercise a lot to realize these benefits. As long as you aren’t completely sedentary after consuming some sugar, any movement helps.

Behavioral change: take a 30-minute walk after every meal.

6. Pairing carbohydrates with protein or fat doesn’t affect the glucose response.

Surprisingly, one of the most common recommendations, that consuming carbs (e.g., fruit) with protein, healthy fat, or both can bring down the glycemic index of the carbohydrate-rich food, and have a positive effect on blood sugar, didn’t work for me.

E.g., a single banana would raise my glucose levels to 6.1 mmol/L / 110 mg/dL, and pairing it with nuts (cashews, Brazil nuts, almonds) has had the same effect. Adding avocado, olive oil, and seeds to a single serving of whole-grain pasta also didn’t make any difference.

Here’s an interesting article and a study if you want to dig deeper into this.

7. Maintaining stable glucose levels during the night is very important.

I’ve had a few nights when my blood sugar would drop dangerously low – to 2.5 mmol/L or 45 mg/dL. As a result, my sleep quality was terrible, waking up was a challenge even after 8 hours of sleep, and I wouldn’t have enough energy during the day.

Why would I have hypoglycemia episodes at night?

The first reason was Berberine which I take used to take instead of Metformin on my workout days. I knew that Berberine lowers blood glucose but didn’t know that it does that so much to cause hypoglycemia.

The second reason was high-carb dinners. All nights with the lowest blood sugar, aside from the Berberine episodes, were the ones when I had rice, pasta, pizza, or any other high-carbohydrate meal for dinner.

These high-carb dinners caused my glucose levels to crash in the middle of the night – my body was going into emergency mode to wake me up.

Behavioral change: I stopped eating high-carb dinners and taking Berberine in the evening.

Continuous glucose monitor is simultaneously a behavioral and analytical tool that can track and uncover strategies and tactics which can save lots of time and money by preventing bad outcomes in the future.

Just like Oura Ring and Apple Watch changed my behavior towards sleep and fitness, drastically improving the quality of my life as a result, CGM has become a remarkable food consumption accountability tool and helped to even further optimize my diet and lifestyle during these two weeks.

Disclaimer: I’m not a doctor, nor do I play one on the internet, so everything in this article is a personal experience and not medical advice. Always do your own research and talk to your doctor before doing any health experiments.

How to Quit Caffeine Without Withdrawal Symptoms

I’ve been drinking coffee every day for the past 15 years.

8 days ago, I stopped, fully expecting massive caffeine withdrawal with headaches, fatigue, decreased blood pressure, etc. – every symptom that I had before even if I skip only a day.

Imagine my surprise when there was none of it: no sluggishness, no headaches, but the same great energy levels and ability to focus.

How on earth did that happen?

One word: adaptogens.

I’ve been adding a mix of adaptogens to my morning cup of coffee – Chaga, Reishi, Moringa, Tulsi, Ashwagandha, Siberian ginseng, Amla, Rhodiola, and Schisandra – for a month before quitting cold turkey.

Here’s why that worked.

The caffeine molecule is structurally similar to our brain’s adenosine, which protects us by slowing nerve cell activity, and basically tells the brain when it’s time to rest or sleep.

Due to its similar structure, the adenosine receptors get blocked with caffeine molecules, keeping them from signaling tiredness. The excess adenosine then signals the adrenal glands to release adrenaline and cortisol (stress hormone), even further increasing your alertness. In other words, by consuming caffeine, you are deliberately putting your body in a stressed state.

After a while, your brain adds more adenosine receptors to compensate for the caffeine, which results in a so-called “caffeine tolerance,” i.e., you need more coffee to get the same effect.

Caffeine also indirectly increases the amount of dopamine (a neurotransmitter that makes us feel good) and serotonin (a natural mood stabilizer) in your brain by blocking their reabsorption into your body. This is why caffeine is addictive. You get used to the elevated dopamine and serotonin levels and miss them without a caffeine boost.

So when you skip your morning coffee, your brain gets flooded with adenosine, the dopamine and serotonin levels in your brain drop, and, as a result, the brain’s chemistry becomes unbalanced, leading to all those nasty caffeine withdrawal symptoms.

This is where the adaptogens come to the rescue.

Adaptogens are natural compounds and plant extracts that help normalize your body’s functions under stress and have been used for thousands of years in Chinese and Ayurvedic medicine.

They help your body to “adapt” (hence the name) to resist better physical stressors like exercise or mental stressors like studying.

Adaptogens also reduce mental fatigue, improve physical endurance and stress resistance, help with workout recovery and anxiety disorders.

When used correctly, adaptogenic herbs normalize your body’s functions rather than stimulate or suppress them.

While caffeine destabilizes your brain’s chemistry leading to withdrawal symptoms without another dose, adaptogens help to balance it out, so you can quit drinking coffee without the consequences.

If that wasn’t enough, Ashwagandha, Schisandra, Eleutherococcus, and ginseng have been shown to extend the life span in some animals, and Rhodiola to strengthen the endocrine system, including the thyroid and adrenal glands (the same ones that caffeine is tricking into releasing extra cortisol).

Some people are concerned by the scarce of scientific research, but the beauty of adaptogens is that they have been proven remedies in human trials for at least a few thousand years.

How to Sleep Better

I’m a sleep nerd. I genuinely believe that a good night’s sleep is a foundation for a highly productive and happy life, and it’s great to see the trend of using sleep deprivation as a badge of honor is finally getting the bad reputation it deserves.

I’d struggled with chronic insomnia for most of my adult life, but now I’m falling asleep in 5 minutes, waking up without the alarm, and my sleep score is almost always above 85.

Oura Ring Sleep and Readiness Scores

This results from years of continuous experimentation to optimize my sleep, and here’s everything that actually helped me:

1. Keep a consistent sleep schedule.

Going to sleep within the same one-hour window every day has had the most impact on my sleep, bar none.

The exact time usually doesn’t work because life happens, and “being late to bed” just gives you anxiety, which will, ironically, ruin your sleep. For me, the perfect window is from 10 pm to 11 pm. You’ll have to find your own “perfect window” because everyone has a different circadian rhythm, and by sticking to the same sleep schedule, you’ll normalize yours.

Your brain and body will know when they are supposed to shut down and relax, which will allow you to fall asleep quickly every day.

2. Don’t use a wake-up alarm clock.

I try to use an alarm to wake up as little as possible. If you need an alarm, you’re, by definition, sleep-deprived. You’ll never need it if you consistently sleep enough. Try to use the alarm only as a backup, and when you do, use the wake-up light alarm clock with sunrise simulation instead of the standard sound-based ones (they shock you into waking up, leading to sleep inertia).

3. Use blue-light-blocking glasses & f.lux after sunset.

There’s an ongoing debate whether blue light has a negative impact or not, but blocking it before sleep seems to work for me. I wear these glasses one hour before bed; they’re not fancy-looking but do the job and block 98% of blue light. f.lux makes the color of your computer’s display adapt to the time of day – warm at night and like sunlight during the day. I’ve been using it for years and love it.

4. No screens in the bedroom and at least an hour before sleep.

My bedroom is a strictly screen-free zone. No phones, tablets, laptops, or TVs are allowed at all times.

The first apparent reason is that blue light from the screens may restrain the production of melatonin and have a negative impact on your circadian rhythm.

But more importantly, the constant influx of information you get from your devices keeps your mind engaged and tricks your brain into thinking that it needs to stay awake. Not to mention social media apps that are designed to give you a positive social stimulus and dopamine influx, which, again, directly inhibits the production and release of melatonin and makes it much harder to unwind.

Make your bedroom a place for sleep and sex only, and watch the quality of your life improves.

5. Avoid caffeine after 12 pm.

That’s highly individual because people with a specific variation of the gene PDSS2 (also CYP1A2, AHR17, ULK3, and NRCAM, but that’s beyond the scope of this article) process caffeine more slowly than others.

You can determine your caffeine sensitivity by taking a DNA test (23andMe or similar ones).

You should also know that the caffeine molecule is similar in shape to the adenosine molecule, a neurotransmitter. It plays a significant role in the sleep-wake cycle. When adenosine binds to enough receptors, it signals the brain that it is time for rest. Caffeine doesn’t replace the need for sleep but masks tiredness since adenosine can no longer do what it is intended to do.

The average half-life of caffeine in healthy adults is 4-6 hours, so if you go to sleep at 10 pm, a general rule of thumb is to avoid caffeine consumption after 12 pm.

6. Exercise any time during the day but at least a few hours before bed.

I’ve found that any type of high-intensity exercise, especially running, during the day does wonders for my HRV. Although, you should avoid very late high-intensity exercise because it’s perceived by the body as a form of stress and stimulates the release of cortisol (also known as the stress hormone), and your body needs some time to return the cortisol level to normal.

7. Read a fiction book before falling asleep.

Reading a fiction book in bed before sleep has become one of my favorite rituals. I think that non-fiction business books before bed stimulate your thought process, and you end up dwelling on your daytime problems. In contrast, fiction books invite you to a new world where you can actually “turn off,” stop thinking about what “you should’ve said or done,” and easily fall asleep. Bonus points if it’s a physical copy so that you wouldn’t stare at a screen.

8. Meditate before going to bed.

I meditate with Headspace for 20 minutes before going to bed. I’ve been doing that for so long that Andy Puddicombe’s (founder of the app) voice now works as a trigger for my brain to wind down and get ready to sleep.

9. Drink chamomile tea with honey and apple cider vinegar.

I got this recipe from Tim Ferris, and it does work as a tranquilizer for me as well. Chamomile tea contains apigenin which helps to lower anxiety levels, and vinegar improves your blood sugar and insulin levels.

10. Take 200-400mg of magnesium 30 minutes before sleep.

I take all of my supplements in the morning except for magnesium, which I’ve found better taken in the evening before sleep. I mostly choose Glycinate or L-Threonate because they are absorbed more easily, while Citrate is considered to have a laxative effect. After a particularly stressful day, I combine it with 200mg of L-Theanine.

Magnesium blocks the activity of more stimulating neurotransmitters and binds to calming receptors, and theanine activates the GABA system, which reduces the activity of the neurons.

11. Maintain a healthy diet and don’t eat after 7 pm.

Nutritionists usually tell you to wait two to three hours between your last meal and bedtime. This allows digestion to happen and the contents of your stomach to move into your small intestine, preventing problems like heartburn and insomnia. Eating also prompts the release of insulin, which plays a huge role in shifting your circadian rhythm.

Bear in mind that nothing from this list would work without a healthy diet. That is, at a minimum, no processed sugars, no junk food, and no alcohol. And speaking of alcohol,

12. Avoid alcohol.

Unfortunately, many people falsely believe that alcohol helps them sleep better because it works as a sedative. What they don’t realize is that alcohol significantly affects the quality of their sleep.

Soon after falling asleep, your body enters a period of deep sleep, when it restores itself physically. Then, a typical sleep cycle includes REM sleep – the mentally restorative stage.

When your body is sedated with alcohol, it can’t reach these restorative stages of sleep because it has to process alcohol in its system instead, and you spend most of your night getting a lot of light sleep, which isn’t nearly as beneficial. So even if you sleep for 8+ hours after a few drinks, you will not wake up feeling rested and recovered.

13. Stay hydrated.

The better hydrated you are, the easier it is for your blood to circulate and deliver nutrients and oxygen to your body. Proper hydration improves HRV, resting heart rate, recovery, and thermoregulation; it helps lubricate joints, remove waste, and prevent infections.

The recommendations for how much water to drink per day vary, but the rule of thumb is ~1 ounce of water for every pound of your weight (or ~70 ml per 1 kg).

14. Keep an optimal room temperature.

You’ll find lots of people saying that keeping the room temperature at 60-68°F (15.5-20℃) is optimal for your sleep.

I find this a bit misleading. There is no universal optimal because it depends on your sheets, body fat, clothing, body temperature, and humidity. The more natural rule of thumb is that you’re not supposed to be too cold (not shivering) or too hot (not sweat). One empirically validated ‘hack’ is to wear socks – keeping your feet and hands warm prevents blood from shunting too much to the extremities and keeps your core body temperature better regulated.

15. Fix the underlying problem.

Many people recommend using weighted blankets and CBD oil because they help with anxiety, which in turn makes falling asleep easier. I haven’t used them because they address the symptom – anxiety – instead of fixing the underlying problem that causes it.

These underlying issues are different for everyone, but the most common ones are stress at work/school, relationship issues, emotional traumas, financial stress, and medical illnesses.

If you want a temporary bandaid to simply help you through a few nights, then sure, CBD oil and weighted blankets will help. But if you want to improve your sleep once and for all, then you’ll have to fix that problem that causes your anxiety.

Sleep tips for traveling.

How to preserve your established circadian rhythm when you travel and change time zones?

There’s a hard way – arrive at a new place, force yourself to live by the new hours for a couple of weeks, and your body will adapt in time.
But, of course, there’s an easier way. Start even before you reach your destination. Figure out what time you’ll be living in, and start living by that time while on the plane. That means you should sleep if it’s nighttime at your destination, even if it’s 10 am your current time.

My recipe for easily falling asleep on the plane:

  • Use a 100% blackout sleep mask (I use Manta Sleep);
  • Get a 100% natural cocktail of Magnesium, L-theanine, and Melatonin;
  • Use noise-canceling headphones (I use Bose QC35);
  • Stay hydrated before and during the flight.

Once you reach your destination, hit the gym, and do a quick workout within an hour of arrival. I don’t know the science behind it, but it almost always helps me eliminate jet lag.

Book, podcast, and gadget recommendations.

People often ask me for books, podcasts, and gadget recommendations, so here’s a special list of everything sleep-related that can help you to sleep better and, as a result, have a better life.


Start with the book Why We Sleep: Unlocking the Power of Sleep and Dreams by Matt Walker.

Many people swear by this book, claiming that it’s changed their lives, and according to Google Scholar, it’s been cited more than a hundred times in academic papers. Walker goes more in-depth on some points I’ve made in this article and touches on CBT-i (the application of cognitive-behavioral therapy to sleep issues). In his book, the key point that Walker makes is that you need at least 8 hours of sleep:

“After being awake for nineteen hours, sleep-deprived people were as cognitively impaired as those who were legally drunk… After sixteen hours of being awake, the brain begins to fail. Humans need more than seven hours of sleep each night to maintain cognitive performance. After ten days of just seven hours of sleep, the brain is as dysfunctional as it would be after going without sleep for twenty-four hours.”

Even though it’s a pop-science book, and there are quite a few factual errors, “Why We Sleep” has probably been one of the most important instruments in raising general awareness of the importance of sleep in recent years, which is all that matters.

After you finished “Why We Sleep,” read the essay “Matthew Walker’s ‘Why We Sleep’ Is Riddled with Scientific and Factual Errors” by Alexey Guzey.

He compares the facts that Walker presented in chapter one with the scientific literature and does a comprehensive review of all scientific and factual errors and an apparent invention of new facts by Walker.

The essay’s main point is to show that if you naturally sleep well and wake up with no alarm clock after less than eight hours of sleep, stick to that. People are different, and not everyone needs the full 8+ hours. Many people tried to sleep more after reading “Why We Sleep,” which led to more awake time, frustration, worry, sleep-related anxiety, and insomnia.


  • Peter Attia, M.D. and Matt Walker, Ph.D., go in-depth on sleep, different stages and cycles, the dangers of chronic sleep deprivation, REM vs. non-REM sleep roles, and much more. So basically, if you don’t want to read Walker’s book, listen to this podcast.
  • Think Your Way Out Of Insomnia by NPR – When you can’t sleep, your thoughts can be your worst enemy. In this episode, Stephen Amira, a psychologist at Brigham, and Christina McCrae, a clinical psychologist and CBT-I expert at the University of Missouri, explain five key strategies to help break the spiral, based on what many believe is the most effective treatment out there: cognitive behavioral therapy for insomnia, or CBT-I.

Sleep gadgets:

  • Oura Ring – as far as I know, this is the best and the most accurate consumer-level sleep tracker currently available on the market. Yes, it’s far from perfect, but this is the best option if you don’t have access to a sleep lab. With a body temperature sensor, infrared LEDs, 3D accelerometer, and gyroscope, it tracks your actual sleep time, sleep cycles (REM, deep, light), HRV score, resting heart rate, respiratory rate, and other things, allowing you to see how are you actually sleep at a glance.
  • Manta Sleep Mask – the best sleep mask that I’ve tested so far (and I’ve tested quite a few of them). It’s highly adjustable, ridiculously comfortable, and offers 100% blackout.
  • Philips wake-up light alarm clock with sunrise simulation – I’ve mentioned this before, but will say this again – you shouldn’t use alarm clocks, but if you do, use this one instead of the annoying sound-based alarms because they shock you into waking up, leading to sleep inertia.
  • The Pod Pro / Cover by Eight Sleep – this is an entire sleep optimization system packed into a mattress. If you and your partner have different optimal sleep temperature preferences, you can easily set your own temperature for each side of the bed. Combine it with sleep tracking and a premium memory foam, and you’ll get an ultimate biohacker’s mattress.
  • White noise machine – I tend to stay in quiet places, but the white noise machine can be a lifesaver if you have a noisy household. It creates a sound that remains consistent across all hearable frequencies, which creates a masking effect that blocks out the sudden changes in noise that can cause you to wake up during the night – the snoring, dog barking, or garbage truck rumbling down the street.

Whatever you do to improve your sleep, remember one rule – don’t stress too much over it.

Ironically, it may backfire and lead to a vicious cycle of ever-increasing worry about sleep, frustration, anxiety, and insomnia.

Take it easy, and gradually implement one change after another to see what each of them does to your sleep.

As always, if you have any questions, suggestions, or want to chat about what worked to improve your sleep, hit me up on Twitter or email me at hi [at]!