TCM · Yin Yang · Eight Principles · Constitution · Diagnosis

Yin & Yang in Health

The primal polarity applied to the living body — a diagnostic framework of extraordinary precision. Every disease, every symptom, every constitutional tendency can be understood as a specific imbalance between Yin and Yang. Identifying that imbalance is the beginning of every TCM treatment.

The diagnostic revolution: Western medicine asks "what disease does this patient have?" TCM asks "what is the pattern of imbalance in this person?" The same disease — say, insomnia — can arise from completely different patterns in different people: Heart Fire blazing, Heart Blood deficiency, Kidney Yin deficiency, Liver Qi stagnation. The treatment for each is entirely different. This is why TCM can treat what Western medicine calls "the same condition" with completely different protocols — because it is not treating the diagnosis. It is treating the person.

Section 01

Yin & Yang — In the Body

Yin and Yang are not fixed substances but relational qualities — each exists only in relation to the other, and each contains the seed of its opposite. In the body, this dynamic polarity manifests at every level: the front and back of the body (front is more Yin, back more Yang), the interior and exterior (interior more Yin, exterior more Yang), the lower and upper body, the blood and the Qi, rest and activity, night and day.

Health in TCM is not the absence of Yin or Yang but their dynamic equilibrium — a living balance that is never static but constantly adjusting. Disease arises when this balance is disturbed in a sustained way: too much Yang (heat, excess, hyperactivity), too little Yang (cold, deficiency, hypoactivity), too much Yin (accumulation, stagnation, dampness), or too little Yin (dryness, heat from deficiency, agitation without cause).

Yin 陰
Cool, cold, moist
Interior, lower body, front
Night, rest, stillness
Blood, Jin-Ye (fluids), Jing
Storing, nourishing, holding
Organs: Liver, Heart, Spleen, Lung, Kidney
Structure, substance, density
Female principle (tendency)
Chronic conditions, slow onset
Pale tongue, slow/deep pulse
Yang 陽
Warm, hot, dry
Exterior, upper body, back
Day, activity, movement
Qi, Wei Qi (defensive)
Moving, warming, protecting
Organs: Gallbladder, Small Intestine, Stomach, Large Intestine, Bladder, Triple Burner
Function, activity, transformation
Male principle (tendency)
Acute conditions, rapid onset
Red tongue, rapid/full pulse

Yin and Yang are the law of Heaven and Earth, the outline of everything, the parents of change, the root of life and death.

— Huangdi Neijing Suwen, Chapter 5
Section 02

The Eight Principles

The Eight Principles (八綱辨證 — Bā Gāng Biàn Zhèng) are the primary diagnostic framework of TCM — four pairs of opposites that together provide a complete characterisation of any disease pattern. Every TCM diagnosis begins with placing the patient's presentation within these eight categories. Yin/Yang is the overarching pair that encompasses all the others.

Yin 陰
Yang 陽
The overarching category — encompasses Interior, Cold, Deficiency. Any condition that is chronic, slow, pale, cool, quiet, hypoactive.
The overarching category — encompasses Exterior, Heat, Excess. Any condition that is acute, rapid, red, hot, loud, hyperactive.
Interior 裏
Exterior 表
Disease in the organs, Blood, bones or deeper tissues. Often chronic. No chills/fever without sweating. Internal causes (emotion, diet, lifestyle).
Disease in the skin, muscles, meridians — the body's surface. Usually acute. Often with chills and fever together. External causes (wind, cold, heat, damp).
Cold 寒
Heat 熱
Cold limbs, preference for warmth, clear/white discharges, loose stools, pale urine, slow pulse, white tongue coating. Caused by Yang deficiency or invasion of Cold pathogen.
Fever, thirst, preference for cold, red face, dark yellow urine, constipation, rapid pulse, yellow tongue coating. Caused by Yin deficiency (empty heat) or excess Yang/Fire.
Deficiency 虛
Excess 實
The body's fundamental substances are insufficient — Qi, Blood, Yin or Yang deficiency. Chronic fatigue, pale complexion, weak pulse, thin tongue. Treat by tonifying what is lacking.
Pathogenic factors are present in the body — Qi stagnation, Blood stasis, Dampness, Phlegm, Heat. Acute onset, strong pulse, thick tongue coating. Treat by dispersing/clearing what is excess.
Section 03

The Most Common Patterns

Within the eight principles framework, TCM identifies hundreds of specific disease patterns. The following are the most commonly encountered in clinical practice — particularly in contemporary Western patients where lifestyle factors dominate.

⚡
Qi Deficiency
氣虛 · Qì Xū · The most common modern pattern
The foundational deficiency pattern — insufficient Qi to power the body's functions. Produced by overwork, poor diet, chronic illness and the general pace of modern life. When Qi is deficient, everything is a little too weak: digestion is sluggish, immunity is low, the voice is quiet, the face is pale and the person tires easily. This is the pattern underlying much of what Western medicine labels "chronic fatigue," "adrenal fatigue" and functional digestive disorders.
Key symptoms
Fatigue · Shortness of breath · Weak voice · Spontaneous sweating · Poor appetite · Pale complexion · Frequent illness · Prolapse (severe)
Treatment approach
Tonify Qi · Strengthen Spleen and Lung · Regular warm cooked meals · Astragalus (Huang Qi) · Ginseng · Avoid overwork · ST 36, SP 6, LU 9
🌸
Yin Deficiency
陰虛 · Yīn Xū · The deficiency pattern of modern excess
When the body's cooling, nourishing, moistening Yin substances are depleted, Yang (heat and activity) becomes relatively excess — producing the characteristic constellation of empty heat: afternoon fever or flushing, night sweats, restlessness and a mind that won't quiet down. Yin deficiency is the pattern of the chronically overworked, overstimulated, sleep-deprived modern person — particularly common in midlife and menopause. It is also the pattern produced by excessive use of stimulants, hot spicy foods, and substances that "burn bright" at the expense of long-term reserves.
Key symptoms
Night sweats · Afternoon heat or flushing · Dry mouth at night · Insomnia with racing mind · Red cheeks · Thin body · Red tongue without coating · Rapid thin pulse
Treatment approach
Nourish Yin · Clear empty heat · Kidney and Liver Yin tonics · Rehmannia (Sheng Di Huang) · Adequate sleep · Avoid stimulants and spicy food · SP 6, KD 3, KD 6
❄️
Yang Deficiency
陽虛 · Yáng Xū · The cold, slow pattern
Yang deficiency is the cold pattern — insufficient warmth and motivating force. The Yang-deficient person is consistently cold (especially the lower back, knees and feet), tired, has low libido, a weak digestive fire (unable to process cold raw food), and a general sense of everything being too slow, too cold, too effortful. Kidney Yang deficiency is the root pattern in hypothyroidism, adrenal insufficiency and many chronic fatigue conditions. It is produced by constitutional weakness, chronic illness, excessive sexual activity (male), prolonged exposure to cold, and too many cold raw foods.
Key symptoms
Cold limbs and lower back · Fatigue · Low libido · Pale abundant urination · Loose stools · Oedema · Pale swollen tongue · Deep slow pulse
Treatment approach
Warm and tonify Yang · Kidney Yang tonics · Moxa on Ren 4, GV 4 · Avoid cold raw food · Cinnamon (Rou Gui) · Du Zhong · Warm cooked foods · Early bedtime
🌊
Dampness & Phlegm
濕痰 · Shī Tán · The modern epidemic pattern
Dampness arises when the Spleen fails to transform and transport fluids properly — producing an accumulation of pathological fluid that makes the body feel heavy, foggy and sluggish. Phlegm is a denser, more congealed form. This is arguably the most prevalent pattern in modern Western populations — produced by excess sugar, dairy, alcohol, processed food, sedentary lifestyle and chronic Spleen Qi deficiency. What modern medicine calls metabolic syndrome, obesity, brain fog, chronic sinusitis, many skin conditions and much cardiovascular disease is Dampness and Phlegm in TCM's understanding.
Key symptoms
Heavy, sluggish body · Brain fog · Bloating · Loose stools · Excess weight · Phlegm/mucus · Sticky sweet cravings · Feeling unrefreshed · Swollen tongue with thick coating
Treatment approach
Transform Dampness · Strengthen Spleen · Eliminate sugar and dairy · Cooked warm food · Movement · Barley (Yi Yi Ren) · Poria (Fu Ling) · ST 40, SP 9, SP 6
🌀
Liver Qi Stagnation
肝氣鬱結 · Gān Qì Yù Jié · The stress pattern
Liver Qi stagnation is the quintessential pattern of modern stressed urban life — the failure of Wood energy to flow freely due to suppressed emotion, chronic stress, irregular lifestyle and insufficient physical movement. The Liver's role is to ensure the smooth flow of Qi in all directions; when this fails, everything stagnates. This pattern underlies PMS, IBS, tension headaches, depression with frustration, and many psychosomatic conditions. It frequently develops into more complex patterns (Blood stasis, Heat from stagnation) when left unaddressed.
Key symptoms
Hypochondriac distension · Bloating · Irritability · Sighing · PMS · Irregular periods · Feeling of a lump in throat · Fluctuating bowels · Wiry pulse
Treatment approach
Move Liver Qi · Regular exercise · Express emotion rather than suppress · Avoid alcohol · Chai Hu Shu Gan San formula · LR 3, LI 4 (Four Gates) · GB 34
Section 04

Reading Your Constitution

TCM distinguishes between the acute pattern (what is wrong now) and the constitutional pattern (the person's fundamental tendency). Understanding constitutional tendency allows for preventive medicine — the practitioner can identify which patterns a person is most likely to develop under stress and take action before disease establishes itself.

Constitutional assessment in TCM uses the four examinations: looking (complexion, tongue, body build, behaviour), listening and smelling (voice, breathing, body odour), asking (the ten questions: temperature preference, sweating, appetite, digestion, sleep, pain, urination, bowels, menstruation, emotional state), and touching (pulse diagnosis at the wrists, palpation of acupoints and abdomen).

ConstitutionTypical appearanceTendenciesKey vulnerabilities
Qi DeficientPale, soft, quiet, tires easilyGentle, thoughtful, prone to worryInfections, digestive weakness, prolapse, fatigue
Yin DeficientThin, dry, often intense, quickDriven, creative, can burn outNight sweats, insomnia, empty heat, dryness
Yang DeficientPale, puffy, cold, slowSteady, patient, can be lethargicCold conditions, oedema, low metabolism, depression
Damp/PhlegmHeavier build, slow metabolism, sluggishMethodical, patient, fixed habitsWeight gain, metabolic issues, brain fog, mucus
Qi/Blood StagnationDarker complexion, tight muscles, intensePassionate, driven, prone to frustrationPain, PMS, cardiovascular risk, emotional suppression
Blood DeficientPale lips and nails, dry hair, anxiousSensitive, empathic, creative but fragileInsomnia, anxiety, dry skin, irregular periods

Most people are mixed: Pure constitutional types are rare. Most people present a primary pattern with secondary elements. The skilled practitioner identifies the root pattern (the most fundamental imbalance) and the branch pattern (the current most prominent symptoms), and develops a treatment strategy that addresses both — typically treating the root when the branch is manageable, the branch when the branch is acute.

Connections
Qi & Vital Substances Meridians & Acupoints Five Elements in the Body Tongue & Pulse Diagnosis Acupuncture Chinese Herbal Medicine Ayurvedic Doshas The Gut Microbiome Taoist Cosmology
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