Tristan Penman's Blog

Why I came back to Australia

23 February 2019

A lot of people ask me why I came back to Australia, or more pointedly, why I left Amazon. It’s a good question, because after spending several years getting a grasp on the basics of Machine Learning, I had found myself in a good team, working on a product recommendation system, powered by a very innovative neural network framework. The problems we faced were fascinating, and I was able to live quite comfortably.

But something was wrong.

At my lowest point, sometime in September 2016, I discovered that I weighed less than 57 kg. That is a very low weight for someone of my height (179cm), with a relatively large frame. To put that in perspective, I weigh 74 kg today, which is about what I weighed when I moved to the US to work for Amazon. And while I lost 17 kg in less than 6 months, it has taken almost two and a half years to put it back on. Some of that delay is intentional - taking care to build muscle mass - some of it is not. I think it is important to talk about the unintentional part. That will help explain why all this happened.

Naming things

I go through life with two potentially overwhelming forces looming over me: anxiety, and trauma.

Giving them names was actually a very challenging thing to do. When you’re inclined to pretend that everything is okay (like me), it is easy to read the textbook definitions and to identify exceptions that, in turn, justify denial. It’s also a step towards owning them. These days, I can speak of my anxiety, and my trauma.

It’s hard to explain what anxiety and trauma are, so I think it will make more sense to explain what they do to me.


For me, the experience of anxiety is like knowing that the realm of nightmares is somehow seeping into the real world, but not being able to see it. These are nightmares in a very abstract sense. It is not usually expressed in a physically grounded way. Which is to say that I’m not necessarily anxious about something, I’m just… anxious.

Since giving it a name, anxiety has become much more predictable for me. I’ve learned to identify triggers, such as exhaustion, lack of family contact. And I’ve found relatively healthy ways to calm it (a sauna session being a particularly good method).

I have experienced anxiety attacks, very true to the textbook definition. Thankfully I can count the number of attacks that I’ve experienced on one hand. My heart goes out to anyone who has had to experience one, and even more so to anyone who gets them more frequently.


Trauma was really hard for me to name. What made it so difficult is that, while I have no shortage of events from my childhood and teenage years that have contributed to it, I was convinced that I had already dealt with all of those events. It was only after seeking professional help that it became clear how dangerous it continues to be.

My experience of trauma can be explained using physical analogies. In the same way that old injuries can flare up and cause pain, emotional trauma does the same thing to me. It leaves emotional scar tissue, and I am certain that it influences my behaviour every day. At the end of the day, it is a learned response to pain.

As I said, trauma is dangerous. But on its own, I find it manageable, and have been able to see it as a valuable way to relate to other people who have suffered through other terrible life events.

The melting pot

So, leading up to my move to the US, I was experiencing an enormous amount of anxiety. I’d gotten my job offer from Amazon, knew that my financial situation was good, and had no reason to be concerned. None-the-less, that horrible sense of the nightmare world was there, and I managed it by over-exercising. That made it was easier to fool myself, because I was at my physical peak.

After arriving in the US, a hectic month of setting up an apartment and getting up to speed in my first team (in Amazon Video) meant that I couldn’t reliably self-medicate with exercise. Soon enough the combination of stress and anxiety caused my appetite to disappear, and at some point, I was probably getting by on one sandwich a day. On some level I knew something was wrong. But I had a deep need to make my move to the US successful, and chose to ignore it.

The active ingredient (?)

When I said that anxiety and trauma are forces that are ‘looming’ over me, I chose that word because their influence is not absolute, but they still have the potential to interfere with my mental calm at any time.

It’s turns out that the combination of the two is potentially deadly. And I know exactly when this happened.

It was during my first week being on-call at Amazon. My anxiety levels were already high, but it was the onslaught of outages and overnight pages that pushed me past my limit. The other engineers in my team later told me that it was the worst week for outages that they had seen in years of working on Amazon Video.

I think it is important to note at this stage that there was no malice or mis-management involved. My manager was great about stepping in and providing support himself. But I was already on the back foot.

At the end of that week, I told myself it was time to get some life balance back, and to relax. I knew I hadn’t been eating enough, and was actually feeling hungry, in a good way. I made an effort to go out and have a favourite meal. But the problem was that I couldn’t stomach it. I was feeling nauseous, and as soon as I got home, I threw up. That was the moment this whole thing switched to deadly.

Feedback loops

It’s hard to explain why that moment was so bad. We’ve all had the experience of being sick and not being able to stomach a meal, but in reality, this was an anxiety attack. After throwing up, and feeling completely overwhelmed, all I felt was cold and… empty. I spent an hour or two in a warm bath afterwards to try and recover.

The problem is that I didn’t really ‘recover’. I slipped back into the same pattern of under-eating. The problem is that this time, I had no intention of correcting it, at least on a sub-conscious level. Food had become linked to the risk of feeling like that again.

To make it even worse, prolonged starvation has other effects. It causes emotions to be supressed, something I found great calm in. It gives you a false sense of focus, and even purpose, as non-essential mental and physiological functions slow down. Even weirder, while I was under weight, I never once yawned.

Crucially, it made the nightmarish anxiety go away, and instead replaced it with a very identifiable food-oriented anxiety. Although I still experienced anxiety around food, I got a certain kind of high from feeling like I was ‘in control’ of the even worse demon. This was the feedback loop.

And no matter what the mechanism, it’s important to admit that this was an eating disorder.


My weight loss would have been accelerated by the fact that I had a lot of muscle mass at the time, which requires more energy to maintain than fat. And despite losing a lot of weight, I was still identifying with my ‘muscular’ self.

It was only when I booked in for a massage because of lower back pain, that I realised what had happened. The massage therapist told me that the back pain was probably caused by my lower back muscles being under-developed. That was complete surprise to me and did not match up with my self image.

When I got home that night, I weighed myself, and learned that I now weighed less than 57kg. I knew this was a bad place to be, and took photos so that I could start to manage a recovery.

Holding patterns

A full recovery didn’t feel attainable at this stage. I was physically weak, and eating was still difficult for me. But over the next few months, I was able to identify ‘safe’ meals. Safe meals were those that I could trick myself into eating without triggering the feedback loop I described above. I managed to find a combination of meals that were nutritionally balanced, and by December I had worked my way back up to 60kg.

It is hard to explain just how challenging that was. When I started tracking my caloric intake in September, I found that some days I would barely reach 1200 calories, and it was reasonable to expect that I needed 2000 or more to put on weight. I also wanted any mass gained to be muscle, if possible.

Making my US move successful was still hugely important to me, and I told myself that if I could just maintain this ‘holding pattern’ for a few years, that would be long enough to achieve some nice career goals, and then to move back to Australia and fix things properly. And as far as I was concerned, I wasn’t hurting anyone.

Hurting people

The thing is, I was hurting people. I just didn’t know it.

Late December, I met up with my Dad for a week in New York. I knew he would notice some weight loss, but I had hoped that with all the extra layers needed for a NY winter, it would be easy to down-play it.

He saw how bad it was right away. And after several long conversations about what was going on, coming from a place of absolute love and compassion, he asked me to come home. At that point, there was no question. Of all of my principles, or values, the most important is that I will never hurt the people I care about. And it was so clear in that moment how much this had hurt him.

Without intending to, I had put myself in an environment where my anxiety and trauma had enough power to compromise my values. Whether in control or not, that is something that I regret. And it is something that I think I will forever be sorry for, both to my Dad and to all of my friends and family.

Where next?

So really, that’s the answer to the question that motivated me to write this. And that is why I have not, even for a single moment, doubted my decision to come back to Australia.

There is so much more that I could have written about this, in the hope that others could benefit from it. I feel like a lot of it, especially the topic of eating disorders, really deserves more attention than it could be given here, so I’ll finish with what I think is the most valuable advice I can give:

If you are struggling, it’s completely okay to seek professional help. And maybe not just okay, but crucial. Mental illness is an incredible burden, and also one that has the potential to impact all of the people around you. If you see it beginning to overwhelm you, talking to someone about it is a powerful step you can take to overcome it.