Health span, Biohacking, and RED-S.
You track your sleep, your HRV, your Zone 2 minutes, and your blood sugar off a monitor you didn't medically need. By every number on your dashboard, you are extremely disciplined.
You might also be slowly starving.
That sounds dramatic. Stay with me, because this is one of the most common things I see in Austin's optimize-everything crowd, and almost nobody is naming it. The wellness internet has quietly rebranded under-eating as a longevity strategy, and a lot of smart, driven people are walking straight into a syndrome that has a clinical name.
The problem with biohacking and optimization:
A huge amount of what the biohacking podcast circuit sells you is running miles ahead of the actual evidence. A charismatic host with a supplement line and a founder with something to promote will present a mouse study, a mechanism, or a single small trial as if it's settled science, and by the time it reaches your earbuds it's a protocol you feel guilty for skipping. Most of it has never been tested in humans doing what you're doing, at the doses being pushed, over a timeframe that would actually matter. And even where a biomarker genuinely nudges, optimization mistakes what's measurable for what matters: it chases the numbers a wearable can show, glucose curves, HRV, a biological-age readout, while ignoring the things that reliably drive a long healthy life and don't fit on a dashboard, like strong relationships, purpose, financial stability, actual rest, and eating enough to run the body you have.
Vigilance has a cost. When your morning is a fasted, cold-plunged, twelve-supplement anxiety ritual, and every meal becomes a math problem you can fail, the stress of managing all of it can quietly undo the very benefits you're chasing. Chronic low-grade stress raises cortisol, wrecks sleep, and suppresses the same systems you're trying to optimize. At some point the pursuit of health stops being healthy, and the most evidence-based thing you could do is relax and eat lunch.
The deeper problem is that optimization treats food as an input and nothing else. Biohackers will measure a meal's glucose curve, its protein grams, its timing relative to a workout, and call that the full picture. But food has never been just fuel. It's also how you celebrate, how you grieve, how your family shows up for each other. It carries memory, culture, and the simple pleasure of tasting something good. Strip all of that out and you're left optimizing a spreadsheet, not a life. A perfect postprandial glucose reading means very little if you flinched away from your grandmother's cooking to get it. Your body isn't a machine you're tuning. It's the thing you actually live inside, and it wants more from a meal than data.
The symptoms the optimizer reads as wins
The early signs of under-fueling look, to an optimizer, like the protocol working.
You feel cold all the time. You call it metabolic adaptation. It's your body turning down the thermostat to save energy.
Your libido quietly tanks. You blame stress, or age, or your phone. Your sleep gets worse. Your training plateaus or slides backward. You catch every cold going around the office. You pick up a nagging stress fracture and assume you trained too hard.
None of these show up on the dashboard flagged as "danger." They show up as data points you can explain away. That's exactly why it goes on for months.
What RED-S actually is (and who it's for now)
RED-S stands for Relative Energy Deficiency in Sport. It's the current clinical model, updated by the International Olympic Committee in 2023, describing what happens when low energy availability, meaning inadequate energy intake relative to what you burn exercising, produces a cascade of health and performance problems.
The key idea is energy availability: the fuel left over for your body once the demand from exercise has been taken out. Push that too low for too long and your body does the sensible thing. It starts switching off functions it considers non-essential.
Here's the part the "Sport" in the name hides, and it matters enormously for this crowd. You do not have to be an athlete. Researchers now write it with a lowercase s on purpose, because you can be at risk even if you would never call yourself an athlete, just someone who exercises regularly. If you train hard and eat around the edges of that training, you qualify.
Take our self-screener to assess for RED-S.
Discipline versus a body that's shutting down
Discipline is a tool. It's supposed to serve your body's function. When your "discipline" is the reason your hormones are flat and your bones are thinning, it has stopped being discipline.
The optimizer's fatal move is reading discomfort as proof of virtue. Hungry means it's working. Cold means it's working. Tired means I'm tougher than the people who eat lunch. But your body isn't grading your character. It's running the math, and when the math doesn't work, it economizes on you.
For some people, this stops being an accident of bad information. Under-fueling framed as optimization is one of the easiest places for a real eating disorder to hide, precisely because the culture applauds the behavior. If restriction has become something you feel anxious about breaking, or the numbers have started running your life instead of the other way around, that's worth taking seriously.
What optimizing would actually look like:
I'm not anti-performance. I'm anti-breaking yourself in the name of it.
If you want a body that works well for decades, the move is not eating less while doing more. It's fueling the training you're actually doing, eating enough carbohydrate to support it, and treating recovery, warmth, libido, sleep, and steady progress as the real biomarkers.
You don't have to wait until you have a stress fracture or a lab result that finally scares you. If any of this is uncomfortably familiar, one honest conversation with someone who understands both training and fueling can save you a year of quietly grinding yourself down.
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RED-S, or Relative Energy Deficiency in Sport, is a syndrome caused by not eating enough to cover both your exercise and your body's basic functions. Over time, low energy availability disrupts hormones, bone health, immunity, mood, and performance. It replaced the older "Female Athlete Triad" model and now formally applies to all genders.
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Yes. Experts intentionally lowercased the "s" to make the point that regular exercisers are at risk too, not just competitive athletes. If you train hard and under-eat relative to that training, you can develop it, race bib or not.
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Common flags include low libido, less reliable morning erections, feeling cold often, poor sleep, frequent illness, stalled or declining training, and stress fractures. In men, chronic under-fueling suppresses testosterone, which is why sexual function is one of the earliest tells.
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Stacking a tight eating window on top of heavy training makes it very easy to slip into low energy availability without noticing. The problem isn't the clock; it's whether you actually eat enough across the day to cover your training. Many hard trainers don't.
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Activity and discipline aren't the problem; under-fueling is. The line gets crossed when the restriction starts degrading function: hormones, bones, sleep, recovery, drive. Discipline that's quietly shutting your body down isn't discipline anymore.
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Stop treating hunger, cold, and fatigue as evidence the plan is working, and get an outside read from someone who understands both training and nutrition. A sports dietitian can help you fuel your actual workload without turning it into another number to optimize.
If you train hard and some of this hit a little too close to home, you don't have to figure out the difference between fueling and under-fueling on your own. Khan RD is in-network with Aetna, Blue Cross Blue Shield, UnitedHealthcare, and Superior HealthPlan.
The content of this blog does not serve as medical advice.
