I am not surprised that I’ve gained weight during the COVID lockdowns. I am 6’1 and now about 190 pounds on a good day, putting me squarely at a 25 BMI.

What I am surprised by is that all my life, I was always the skinny kid. When I was 20, I weighed 130 pounds. A 17 BMI. Even earlier, when I was an even thinner teenager, my mom was so concerned about me being underweight that she routinely took me to get fast food and waffles in the hopes that I’d put a bit of meat on my bones.

As a young adult, I would never get hungry. Or when I did, it was easy for me to ignore it and keep pushing on whatever I was doing. Emotionally, I hated eating. I thought it was a big waste of time, and never enjoyed waiting around at a lunch or dinner table. I still feel that way. Back then, my favorite foods were exclusively salads, and I didn’t care much for meat.

Today, a decade later, I still hate the idea of eating, but I have cravings for food. If I’m bored, I might go eat by default. I might be working, and suddenly get distracted by the thought of a bacon sandwich. All day long, I’m snacking like a slave to refined carbs. Of course I haven’t eaten a salad in a long time, but I’m chowing down burgers and fries on the regular. Writing this paragraph is making my mouth water.

At this point, I feel like I’m suffering from a food addiction: I have totally lost my willpower and self-control around food. I don’t even enjoy it deeply – I’m not a “foodie” – it’s just a quick fix. The body demands more fat, salt, and sugar, and I fulfill those demands unquestioningly. I know enough about the interaction between the slow-changing gut microbiome and the brain to understand that the bacteria in my intestines, spawned by my diet, have the power to impact my behavior. In other words, I am literally a slave to my diet. The cravings that I have are no coincidence, but the outcome of a diet that has self-reinforced in particular ways.

But why? Well, I moved to the United States for college. Before then, I was mostly growing up in Tokyo and Sydney. Especially Tokyo is a lean place. Back then, my attitude toward weight loss was simple: just don’t eat. I didn’t understand why people struggled with it so much. It turns out that disciplined eating requires a lot of cognitive control. Once I moved to the US, my diet changed slowly but surely, and I’ve felt myself lose that control. There’s something in the water, you say? Probably, but more pressingly, there’s something in the food. You are what you eat.