If I told you there's a disease that one in three American adults already has, that you can't feel, that won't get flagged on a routine physical, and that is quietly setting you up for type-2 diabetes and heart disease, you'd want to know if you were one of them.
Here's the uncomfortable part. As aircrew, the odds aren't one in three. They're worse. A lot worse.
The condition is fatty liver. The medical world recently renamed it MASLD, which stands for metabolic dysfunction-associated steatotic liver disease. The new name matters, because it finally says the quiet part out loud: this is not a drinking problem. It's a metabolism problem. And our job is practically engineered to break metabolism.
What it actually is
Your liver is supposed to store a small amount of fat. Fatty liver is when that storage gets out of hand, when more than about five percent of the organ is fat. Push it far enough and it moves from quiet fat accumulation, to inflammation, to scarring, to the kind of damage you don't walk back from.
The reason almost nobody catches it early is that it is silent. No pain. No symptom you'd ever connect to your liver. You feel tired, foggy, soft in the middle, and a little off, and you chalk it up to the schedule. Meanwhile the standard liver enzymes on a basic blood panel, ALT and AST, can sit in the so-called normal range while the liver is already loading up with fat. Your AME clears you. Your annual physical says you're fine. The problem is that “fine” was never actually measured.
Why your body does this
The driver isn't dietary fat. It's insulin resistance and a process called de novo lipogenesis, which is a fancy way of saying your liver is turning excess sugar and refined carbohydrate into fat and parking it on site.
When you're constantly riding a blood-sugar roller coaster, terminal pretzel here, energy drink there, hotel breakfast carb-bomb, late-night layover meal, your insulin stays elevated. Chronically high insulin tells the body to store, not burn. The liver becomes the warehouse. Over months and years, the warehouse fills up.
That's the mechanism. Now look at how our job feeds every single input.
The crew risk stack
Stack these on top of each other and you start to understand why this hits us harder than the 9-to-5 crowd:
Circadian disruption. Your liver runs on a clock. So do your blood sugar and your hormones. Crossing time zones and flying back-of-the-clock trips scrambles that clock, and circadian misalignment is independently linked to the same metabolic dysfunction that drives fatty liver. You are not imagining that red-eyes wreck you.
Garbage sleep. Short, broken, daytime sleep raises insulin resistance and cortisol. Cortisol tells your body to hold visceral fat, the deep belly fat that surrounds your organs and pours fuel onto a fatty liver. Bad sleep isn't just fatigue. It's a metabolic event.
Hotel and airport food. Ultra-processed, sugar-heavy, refined-carb everything, eaten at random hours because that's what's open. It is almost a perfect recipe for the exact process described above.
Layover alcohol. Even moderate drinking stacks directly on top of the metabolic damage. The newest research even has a category for people who carry both the metabolic and the alcohol load at once, and crew life makes that combination easy to fall into.
The chair. Long-haul sitting and low daily movement drop the body's ability to clear sugar out of the blood, which sends more of it to the liver to be stored as fat.
None of these are character flaws. They're the operating conditions of the job. But your liver doesn't care that you have a good reason.
The part that should give you hope
Here's what makes this worth writing about: caught early, fatty liver is one of the most reversible conditions in medicine. The liver wants to heal. Give it the right conditions and it will offload that fat, often faster than people expect.
The right conditions aren't a crash diet or a month of misery. According to my functional medicine partner, Dr. K. Andrew Shepard, DC, CN, of Life Visions, the needle-movers are the unglamorous ones: pulling out the added sugar and refined carbs that feed the storage process, getting blood sugar and insulin back under control, protecting sleep like it's a checklist item, moving daily even when you can't get to a gym, and being honest about the layover drinks. The body responds. It just needs the inputs to change.
But, and this is the whole point, you cannot fix what you've never measured. The reason most crew members spin their wheels is that they're guessing. They assume their “normal” annual labs mean their metabolism is healthy, when those labs were never designed to catch this. The real picture lives in the markers most physicals skip: fasting insulin, HOMA-IR, HbA1c, the triglyceride-to-HDL pattern, GGT alongside ALT and AST. That's the data that tells you whether your liver is quietly filling up, and exactly which lever to pull first.
That's the entire reason we test before we coach. Two people with the identical symptom can have completely different root causes, and a generic plan aimed at the wrong target is just more wheel-spinning. When you can see what's actually happening under the hood, you stop guessing and start fixing.
Where to start
If you're reading this and recognizing yourself—foggy, soft in the middle, tired in a way sleep doesn't fix—you don't need to panic. You need a baseline. Find out what your metabolism is actually doing instead of assuming. From there, the fix is real, and for most people it's faster than they think.
You built a career that never stops moving. Your liver shouldn't be the thing that finally grounds you.
Scott Darragh is a commercial airline pilot and the founder of Jet Set Trainer, a metabolic health and performance coaching program built for pilots, flight crew, and frequent travelers. Clinical lab interpretation referenced in this column is provided by Dr. K. Andrew Shepard, DC, CN, of Life Visions, an independent functional medicine partner. Curious where your own metabolism stands? Take the free metabolic health survey at jetsettrainer.com/bhe.
This article is for educational purposes and is not medical advice. Talk to your physician or AME before making changes to your health routine.
