6LETTERS

A week with brutally long overtime, 

or a Friday evening when your body feels heavy as lead from daily stress. 

As if by unspoken agreement, we casually toss a word to a colleague or family member:

“I feel so low on energy today, shall we go eat some eel?”

The interesting part is that this culture isn't a unique quirk exclusive to Koreans. 

Neighboring Japan also lining up on ‘Doyo no Ushi no Hi’ (土用の丑の日, a day similar to the dog days of summer) 

to eat unagi (eel) to beat the summer heat, 

and in China as well, eel has long been regarded as the ultimate energy booster 

for both the royal court and commoners alike.

Of course, from the perspective of modern medicine, 

eating a few pieces of eel tail won't suddenly cause sleeping male hormones to explode like a volcano. 

Then why, out of so many stamina foods, 

does humanity instinctively think of 'eel' specifically when tired? 

Behind this lies a very honest and precise physiological signal sent by our brain and body.

1. Brain's Navigation: The 'Nutrient-Density' Signal Sent by the Hypothalamus

 

The feelings we often express as 

“having no energy,” “feeling sluggish,” or “lacking motivation” aren't just mere mood issues. 

It is a red alert from the body indicating that energy has been depleted at the cellular level due to accumulated lack of sleep, chronic stress, and fatigue of the autonomic nervous system.

At this moment, the Hypothalamus, which governs the homeostasis of our body, 

starts tapping on a very clever calculator.

‘Currently, the energy metabolic rate is at its worst. 

Rather than rough foods that require a lot of energy to digest, find high nutrient-density food that can fill explosive calories and essential nutrients simultaneously even with a small amount.’

Eel is an organism that perfectly satisfies these strict conditions of the hypothalamus. 

Eel is not simply 'fatty meat'.

• High-quality essential amino acids (protein) reaching about 20g per 100g

• High content of Omega-3 fatty acids (EPA, DHA) that soothe vascular inflammation and restore cell membranes

• Vitamin A (retinol), essential for skin and mucous membrane regeneration, tens of times higher than in regular fish

There are few 'comprehensive nutrient cocktails' as excellent as eel 

for an exhausted body to repair cells and yield immediate energy. 

Our bodies remember this nutrient density accurately through experience and instinct.

2. The Hidden Helpers of Testosterone: The Collaboration of Zinc and Vitamin D

 

The reason eel became the 'symbol of stamina' isn't simply because its appearance wriggles energetically. 

Looking closely at the micronutrients abundant inside eel 

makes you nod in agreement as to why eating this food gives you power. 

They are Zinc and Vitamin D.

In sports medicine and endocrinology, 

these two nutrients are considered key cogs in maintaining the secretion rhythm of male hormones (Testosterone).

Mechanism of Zinc (Prasad AS et al., 1996): 

According to the research by Dr. Prasad, 

when zinc intake was restricted in normal young men, 

serum testosterone levels dropped nearly by half in just 20 weeks. 

Conversely, when zinc was supplemented in hypogonadal men with zinc deficiency,

hormone levels rose dramatically. 

Zinc is an essential substance for activating Leydig cells 

that produce testosterone and for the balance of 5$\alpha$-reductase.

Mechanism of Vitamin D (Pilz S et al., 2011): 

In clinical research by Dr. Pilz, men with higher vitamin D levels 

maintained significantly higher testosterone levels 

compared to those who did not. 

This is because Vitamin D acts not as a simple vitamin, 

but as a kind of 'prohormone' that activates hormone receptors.

Of course, eating eel won't infinitely increase hormones in a person 

who is already in a state of nutrient excess. 

However, for modern people whose nutrient balance is temporarily broken 

and hormone rhythms have hit rock bottom due to overwork, 

staying up late, and stress, 

the rich zinc and Vitamin D provided by eel 

serve as an excellent 'raw material supply' to restart the broken hormone factory.

3. The Dichotomy of Recovery: What You Ate vs. How Your Body Receives It

 

However, here we must ask a one-step deeper question.

“Why is it that after eating the exact same eel, 

someone opens their eyes wide the next morning 

while someone else suffers indigestion and feels fatigued all day long?”

The answer lies not in the food itself, 

but in the individual's autonomic nervous system (ANS) 

and hormonal state receiving it.

Eel is a food very high in protein and fat content. 

To digest it completely and absorb it into body energy, 

the parasympathetic nervous system must be activated 

to supply sufficient blood flow to the gastrointestinal tract.

If a person is experiencing mental work stress even while eating eel, 

or if the sympathetic nervous system is extremely tense due to chronic sleep deprivation (JAMA, 2011), 

the gastrointestinal tract shuts its doors. 

The high-nutrient food fails to be absorbed and acts as toxins, 

placing strain only on the liver and stomach, causing even worse fatigue the next day.

Ultimately, what matters is not “What to eat,” 

but “How to respond (whether my body is in a state ready to receive those nutrients and switch to recovery mode).” 

This is the exact reason why we should monitor our Heart Rate Variability (HRV) 

and deep sleep patterns every morning using smartwatches. 

If the balance of your body's autonomic nervous system is broken, 

even the best stamina food in the world is like pouring water into a bottomless pit.

4. Another Miracle Happening in Front of the Grill at the Eel Restaurant: Restoration of Emotional Homeostasis

Come to think of it, the scene when we go to eat eel is usually similar. 

It is rare to order grilled eel alone through a delivery app in solitude. 

Mostly, we sit around a sizzling eel grill with team members 

after successfully finishing a project, 

with an old close friend, or with parents.

Clinking glasses together, warm language of solidarity flows back and forth: 

“You went through a lot,” “Let's eat this and gain strength.”

Physiologically, at this moment, another important hormone is secreted in our brain: 

Oxytocin, which provides emotional bonding and stability, and Serotonin, which causes feelings of happiness.

It is a moment when the emergency siren of the HPA axis (Hypothalamic-Pituitary-Adrenal axis)—

which was overheated by chronic stress—

turns off, cortisol levels drop, and the body finally enters 'Rest and Digest' mode. 

Perhaps the real reason we gained strength after eating eel wasn't just because of the calories in eel, 

but thanks to the sense of security, rest, and restoration of relationships obtained 

through the medium of eel.

Conclusion: True Nourishment (保養) Begins with Noticing Yourself

 

The nourishment culture that humanity has carried onfor thousands of years 

is not mere superstition or a placebo effect. 

It is a very wise homeostasis recovery mechanism 

that supplies nutrient-dense food, rests with good people, 

and restores broken biological rhythms.

Future health management will move away from the one-dimensional approach of 

"I'm tired, so let's cram something good for the body inside." 

It should move toward precisely noticing through data and senses why I am tired right now, 

whether sleep is lacking, 

whether autonomic nervous system balance (HRV) is broken, 

or whether nutrients are truly lacking.

Tonight, is what you truly need the fatty food called eel itself, 

or a short rest and comfort shared with precious people in front of a warm grill? 

Listening to the true voice of your body—

that is the beginning of true nourishment (保養) spoken of by modern physiology.

#6letters, #mojoking, #mojoqueen, #mojocare, #hormone, #digitalhealthcare,

References

• Prasad AS et al. (1996). Zinc status and serum testosterone levels. Nutrition.

• Pilz S et al. (2011). Vitamin D and testosterone in healthy men. Clinical Endocrinology.

• Leproult R, Van Cauter E. (2011). Effect of sleep restriction on testosterone levels in healthy young men. JAMA.

• Irwig MS. (2012). Depression and hypogonadism in men. American Journal of Men’s Health.