Working for a Health Startup Didn't Make Me Healthier: Marko Tarnaj's Biological Age Journey

Knowing the science and living it are two very different things. As CPO of GlycanAge, Marko Tarnaj understands exactly how biological age is measured and why it matters. But when he took his own test, his result came back eighteen years higher than expected. He spent years experimenting, moving countries, and searching for the interventions that would finally move the needle. What he found was a simple truth: sustainable habits will always outlast quick interventions.
 

From what I know, when you took your first GlycanAge test, it came back as 46 years old, which was around 18 years more than your chronological age. That seems like quite a big difference. What was your initial reaction to that? Could you walk me through that experience?

Back then, I was with Jaspero, the development agency behind GlycanAge, and we all got tested together. At the time, I think I was the most physically active person in the office. I was running, going to the gym, and paying some attention to my diet, though not as much as I could have. Weight-wise, I was in the best shape I'd had, which is why I expected a good score.

But when the results came in, pretty much everyone was older. One of the guys scored the highest, around 25 years older. And the only person who came out younger was someone who smokes. We were very surprised. The way we justified his result was that he had just gotten engaged and was getting married, so all those good hormones must have offset everything else.

After that initial reaction, I had a consultation with a GlycanAge specialist. I was recommended omega-3s through fish oil, cod liver oil specifically. I also tried to cut out alcohol completely, and I didn't have any for six months. The third thing was vitamin D, since any physical activity I was doing was usually in the afternoon when the sun was already gone, and the rest of the day I was working from home. I did all of that for six months, and in six months, I dropped 10 years, bringing my GlycanAge down to 36. I was quite surprised.

However, the next time I tested, it climbed back up to around 51, even higher than where I started. There was a period of several years where it sat somewhere between 45 and 55. During that time, I was trying anything and everything, but nothing really worked.

Looking back at those years of fluctuation, was there anything happening in your life that might explain why your results were stuck?

Retrospectively, yes. That was the period when I moved to the UK, my first experience of living alone. When I was in Newcastle for four months, it was the first time I'd ever lived away from home. Moving somewhere new is stressful. Getting used to a completely different environment is mentally draining. And I was coping with all of that by doing more physical activity, running a lot. Looking back, it wasn't the right thing to do. A better approach probably would have been to go and make some friends. But honestly, it's easier to go running than make friends. 

Then I moved to London, and moving multiple times in a short period brings its own instability. The social aspect improved, but I still wasn't feeling settled. And by settled, I mean stable. There was nothing long-term. I didn't know how long I was going to stay anywhere. It wasn't something I actively stressed about, but it was always there in the background. There's also a study showing that changing your environment impacts your immune system because your body encounters a completely different set of bacteria, and it takes time to adapt. 

It sounds like the fluctuations you experienced during those years weren't that drastic. You weren't moving much in either direction, you almost reached a plateau. How did that feel, and what eventually changed?

It was quite annoying, honestly. Frustrating. I was trying out different things, certain supplements for a while, then others. But retrospectively, what your body really wants is just balance. 

After going through all of those experiments, I said, okay, I'll just commit to something for at least a year, and then we'll see. By that point, I had some stability, a long-term rental, and some healthy habits forming. My diet was on point. I developed a breakfast that I have literally every single day, and I have four different meals I cycle through for lunch. For dinners, I usually cook something from Riverford, a service in England that delivers organic ingredients with recipes. That's basically my diet.

I've also been consistently going to the gym roughly six days a week, which I know sounds like a lot. But I put a lot of emphasis on rest too, three days on, rest, three days on, rest. It seems like that combination of stability, diet, and regular exercise is what finally moved the needle. My latest GlycanAge result dropped by 10 years.

You've touched on diet and exercise, but were there any other lifestyle changes that contributed to that result? 

A few things. Aside from going to the gym six days a week, I realized that gym sessions alone aren't enough for daily activity. You also need to hit roughly 10,000 steps a day. I was doing that before, but all in one go. This time around, I split it up. A loop around the park, four times a day, morning and evening, and once somewhere in between.

When it comes to supplementation, I've actually removed almost everything. The only thing I kept was vitamin D. I used to take B complex, omegas, and a few others, four supplements in total. But I eat fish every day, sometimes twice, so I don't need omegas. And I realised my diet was already strong, so adding more supplements on top wasn't necessary. The one thing a diet can't really fix if you live in the UK is vitamin D, so that stays.

Sleep has also been a big one. For years, my Oura ring was telling me to go to bed between 10 and 11 pm based on my chronotype, and for years, I ignored it. I'd just go to sleep whenever I was done with whatever I was up to, video games, scrolling, usually between 11 and midnight. But I eventually gave it a shot. At 9:30, I'd start winding down. If friends had sent me reels to watch, I'd go through those earlier in the evening rather than in bed. If I were watching Netflix or gaming before sleep, I'd put on blue light-blocking glasses. Sometimes I'd read or do puzzles. I started to focus on preparing for bed properly, getting there on time, and going to sleep stress-free.

Have you changed anything in terms of your social habits? It sounds like the move to the UK was quite a lonely period.

Growing up in Croatia, in Osijek, I could hang out with friends every single day. It wasn't something I always did, but I always had access to people. When I moved to Newcastle, I was completely alone for four months. It was an interesting experience.

Then in London I lived in shared households, the kind where four or five people each have their own room, sometimes their own bathroom, but there's always someone around. I lived in two houses like that, and I did form some real friendships. I still hang out with those people to this day. But when it came time to look for something new, I realised I actually prefer living alone.

I love my peace. During the week, it's just quiet in my apartment, which I love. And then on weekends, I go hang out with friends, walk around, and grab lunch. I came to terms with the fact that I need a bit of both.

I want to turn our discussion to a different point. You're in quite a unique position, being both a GlycanAge user and a GlycanAge employee. Since you've been part of the team that developed the product, did it make you a bit more receptive to the high result that you saw?

While I trust the science behind the test, I am not so quick to trust the interventions that I implement and the results that they might produce. There are always outside variables that are difficult to account for, which is why I wanted to keep tracking my data over a longer period of time to see a trend.

When my results were going up and down, I wasn't ready to draw any conclusions, because in the background, I'm constantly changing things, and there's a lot happening in my life. So my approach was: I needed a longer runway before I could trust this. I didn't want to base anything on a three-month intervention. I want to sustain something for at least one to two years before I can say there's a real trend. 

Going back to exercising, the established recovery period tends to be around 48 hours, but with you exercising six times a week, that doesn't quite fit in. Why did you go down that road?

I do a push-pull legs routine. Any routine is usually measured by the week, and traditionally, there's an upper and lower split. Monday upper body, Tuesday lower body, Wednesday rest or cardio, Thursday upper, Friday lower, weekend off. So if you did upper body on Monday, you're resting Tuesday and Wednesday, and hitting it again on Thursday. This way, your muscles have enough time to recover.

With a push-pull legs routine, it's push on Monday, pull on Tuesday, legs on Wednesday, then you repeat the cycle until Saturday, and on Sunday, you rest.

Could you elaborate on what exercises fall into each of those categories?

Push is your push muscles: chest, triceps, and the front part of your shoulders. Pull is your back muscles and biceps, the muscles that pull. And legs are self-explanatory.

The usual routine runs until Saturday, and then you rest. But I modified it because I'm not really constrained by a seven-day week. I do push, pull, legs, rest, and then repeat. So I add an extra rest day, and my workout week is technically eight days, but I'm not bothered by that because I don't care what day it is. I work pretty much every day, and I work out pretty much every day, so I'm fine with it. I know that for someone who has to go to an office every day, it would be a lot more difficult.

I wanted to follow up on that because we recently had an overtraining webinar where we discussed how not giving your body and muscles enough rest can accumulate fatigue, leading to loss of motivation and poorer performance. But somehow, the routine you described is working for you, isn't it?

Completely. And I think I now understand what overtraining is, because I spoke to a guy at the gym who asked me about my routine. I explained it to him, and he also trains six times a week. So I asked him what he does, and he said every day he does a full-body workout and cardio as well. I was like, “What? What are you taking, buddy?”

I do four different exercises each day. If it's a compound movement, I'm going to do only two sets, but I'll put as much weight as I can and push myself to failure in both of those sets. For isolation exercises, I do three sets, because it's usually smaller muscle groups and they can handle a bit more load. It's all very kind of calculated, and I've been journaling all of this, writing everything down, talking with myself, talking with AI, and going through it all the time, analyzing my progress. I've also been making sure to weigh myself. Over the course of a year, I've managed to gain roughly four kilos, which is pretty good.

Since you are very much into experimenting, is there a next experiment you would love to test out?

Absolutely not. Now I just want to keep doing this and see if it was a one-off thing or if it actually works. I've been applying these interventions for a while now, and I want to see if prolonging that period even further is actually worth writing a post on LinkedIn.

As someone who has had experience seeing higher results than expected, what would your general recommendation be for people when they see such a result? What would you tell them?

Figure it out. And I know that's a difficult answer because there are so many contradictions. I want to say you should not listen to other people, but at the same time, you also should. So the answer is probably that you should listen to your own body.

But I don't think people know how to do that. Retrospectively, I had no idea what it actually meant. I love exercising, I want to do it every day, and I'm happy I found something that works for me daily. But for some people, it might not work.

When I said you shouldn't listen to other people, I meant things like intermittent fasting. People will tell you it's incredible for you. I personally tried it, it sucked, I hated it, and I stopped. But what I did try was a 24-hour fast, a 48-hour fast, and a 72-hour fast, and those are amazing for me. The 72-hour one is basically three days where you're just on tea and water, nothing else. But I felt really good. Obviously, you shouldn't do any physical exercise during that period, but when it comes to work, I am so much more focused.

Aside from intermittent fasting, have you found any other general lifestyle intervention recommendations not useful?

No, I think intermittent fasting is the one that stands out. 

But one thing I used to consider bad advice that I actually found really nice is journaling. There's something called a five-minute journal, and you do it both in the morning and in the evening. You have three morning questions and two evening questions. One of the morning questions is 'what are the three things that would make today great?' and one of the evening questions is 'what are the three things that happened today?' I loved it. 

I was already considering just writing down my thoughts, and I do have a notebook for that, but the five-minute journal is so good because it asks you what you are actually grateful for each day. And I think that question has a lot of power. It grounds you.

Every day, people worry about so many things that are not really important, but when you sit down and think about what you are actually grateful for, it changes your perspective on everything that you have.