▲ Classification of Constitutions
The study of constitution in Traditional Chinese Medicine (TCM) primarily determines the differences in individual constitutions within populations based on fundamental theories such as Yin-Yang, the Five Elements, Zang-Fu organs, and the essence, Qi, blood, and body fluids. The specific classification methods include Yin-Yang classification, Five Elements classification, Zang-Fu classification, body shape classification (fat and thin), and temperament classification (brave and timid).
1. Methods of Constitution Classification
TCM uses the theory of Yin-Yang to elucidate the laws of life movement, explaining the issues of health and disease. Therefore, TCM primarily classifies constitutions based on physiological functional characteristics using the Yin-Yang theory. This section adopts the Yin-Yang classification method for constitution classification. It should be noted that the terms used in constitution classification, such as Yin deficiency, Yang deficiency, Yang excess, phlegm-dampness, spleen deficiency, and liver excess, are different concepts from the syndrome names used in syndrome differentiation and treatment, reflecting an individual specificity that exists even in a non-disease state.
2. Normal Constitution
“When Yin and Yang are balanced, it is called a person,” and “When Yin is balanced and Yang is secret, the spirit is treated.” Therefore, the ideal constitution should be one of balanced Yin and Yang, but the balance of Yin and Yang is a dynamic equilibrium of their growth and decline, so there is always a state of relative Yin or Yang. As long as it does not exceed the body’s regulatory and adaptive capacity, it is considered a normal physiological state. Thus, the normal constitution of the human body can be roughly divided into three types: balanced Yin-Yang constitution, Yang excess constitution, and Yin excess constitution.
(1) Balanced Yin-Yang Constitution
Balanced Yin-Yang constitution is a constitution with relatively coordinated functions. Individuals with this constitution are strong, with a moderate body shape; they may be plump but not sluggish, or thin but spirited. Their complexion and skin tone may show a bias towards the five colors, but they are all bright and subtle, with spirited eyes, a gentle and cheerful personality, moderate appetite, smooth bowel movements, and strong self-regulation and adaptability. Those with a balanced Yin-Yang constitution are not easily affected by external pathogens, rarely fall ill, and if they do, they often recover spontaneously or are easily cured; they have abundant energy, great work potential, sleep soundly at night, and have high efficiency in rest. If they receive proper postnatal nourishment without violent trauma or chronic diseases, their constitution is not easily altered, and they are likely to achieve longevity.
(2) Yang Excess Constitution
Yang excess constitution refers to a constitution characterized by excessive excitement, heat, and hyperactivity. Individuals with Yang excess constitution often have a lean but firm physique. Their complexion is often slightly red or slightly dark, or they may have oily skin; they are extroverted, active, easily irritable, and have poor self-control; their appetite is larger, and their digestive absorption function is robust. Those with Yang excess constitution are usually sensitive to heat, prefer coolness, may have slightly elevated body temperature, sweat easily when active, and have a strong libido.
Individuals with Yang excess constitution are more susceptible to wind, heat, and summer heat pathogens, and when affected, they often present with heat syndromes, excess syndromes, and may develop dryness and injure Yin. Their skin is prone to boils. Internally, they often present with conditions of excess heat, Yang excess, or combined Yin deficiency, leading to dizziness, headaches, palpitations, insomnia, and bleeding.
Such individuals have excessive Yang energy, are hyperactive, and have heat that consumes Yin. Coupled with excessive labor, unregulated thoughts, and indulgence, this will accelerate Yin injury and develop into common pathological constitutions such as Yang excess, Yin deficiency, and phlegm-heat.
(3) Yin Excess Constitution
Yin excess constitution refers to a constitution characterized by insufficient Yang, coldness, and inactivity. Individuals with this constitution often have a plump but weak physique, are easily fatigued; their complexion is pale and lacks luster; they are introverted, prefer quietness, and may be timid and easily startled; their appetite is small, and their digestive absorption function is average; they are usually sensitive to cold, prefer warmth, or have slightly low body temperature. Their energy is relatively weak, movements are slow, and reactions are sluggish.
Individuals with Yin excess constitution are more susceptible to cold and damp pathogens, and when affected, they often present with cold transformation, with no or low fever, and may easily transmit to the interior or directly affect the organs. They are prone to frostbite in winter. Internally, they often present with conditions of excess Yin and Yang deficiency. They are likely to develop stagnation of dampness, edema, phlegm-dampness, and blood stasis; individuals with this constitution have weak Yang energy, which can lead to insufficient Yang energy, weak organ functions, and internal generation of dampness, resulting in common pathological constitutions such as Yang deficiency, phlegm-dampness, and phlegm-retention.
▲ Application of Constitutional Theory
The specificity of constitution is determined by the strength and weakness of the Zang-Fu organs and the abundance and deficiency of Qi and blood, reflecting the uniqueness of the body’s Yin-Yang movement. Due to the specificity, diversity, and variability of constitution, there are significant differences in individual susceptibility to diseases, the nature of pathological changes, the disease process, and responses to treatment. Therefore, TCM emphasizes “tailoring treatment to the individual” and closely integrates constitutional theory with etiology, pathogenesis, diagnosis, treatment, and health preservation to guide clinical practice.
1. Constitution and Etiology
Constitution determines susceptibility to certain pathogenic factors and diseases. Different constitutions have specific susceptibilities to certain pathogens and diseases. TCM has long recognized this phenomenon, and there is a saying regarding the susceptibility of certain constitutions to corresponding pathogens, known as “like attracts like”. For example, individuals with a cold constitution are often Yang deficient, feel cold, and are susceptible to cold pathogens, leading to cold diseases; when affected by cold pathogens, it is also easy to penetrate the interior, often injuring the Yang energy of the spleen and kidneys; individuals with a dry-red constitution are often Yin deficient, intolerant of heat, and easily affected by warm pathogens; individuals with a sticky constitution have excessive dampness and are susceptible to damp pathogens, often leading to diarrhea or swelling due to external dampness triggering internal dampness. The Neijing also records, “Those with weak Zang organs are prone to consumption diseases,” “Those with weak bones and flesh are prone to cold and heat diseases,” and “Those with coarse skin and weak flesh are prone to obstruction diseases” (from Ling Shu: Five Transformations). This shows that due to the differences in the strength and weakness of the Zang-Fu organs, individuals with different constitutions also have different disease occurrences. Obese individuals often have phlegm-dampness and are prone to stroke; thin individuals often have heat and are prone to tuberculosis; elderly individuals with kidney decline often have phlegm-dampness, cough, and asthma. All these indicate that the bias in constitution is the fundamental reason for the body’s susceptibility to certain diseases.
2. Constitution and Disease Occurrence
TCM believes that deficiency of Zheng Qi (the body’s righteous Qi) is the internal basis for disease formation, while pathogenic Qi is merely an external condition for disease formation. The presence of pathogens must be due to the deficiency of Zheng Qi. If Zheng Qi is deficient, pathogens can invade; if Zheng Qi is strong, pathogens cannot easily enter. Zheng Qi is determined by constitution, and the strength of constitution determines the deficiency or excess of Zheng Qi. Therefore, the internal factors for disease occurrence largely refer to the individual’s constitutional factors.
Constitution determines whether a disease occurs and the nature of the disease: the strength of constitution determines whether one is susceptible to external pathogenic Qi. After the body is affected by pathogens, due to different constitutions, the occurrence of disease varies. Some may develop the disease immediately, some may not, and some may have relapses. A robust constitution with strong Zheng Qi is less likely to become ill; a weak constitution with internal deficiency of Zheng Qi is more prone to illness. For example, individuals with spleen Yang deficiency may experience diarrhea after consuming cold foods, while those with strong spleen and stomach can eat cold foods without falling ill. It can be seen that whether the body becomes ill after being affected by pathogenic Qi often depends on constitution. Of course, we must not deny the role of pathogenic Qi just because we emphasize the role of constitution in the disease process. It is well known that without pathogenic Qi, disease cannot occur. However, even if the body is affected by pathogenic Qi, due to different constitutions, it does not necessarily lead to illness; even if illness occurs, the clinical type and disease course also vary from person to person.
3. Constitution and Pathogenesis
1. The Transformation of Constitution and Pathogenesis: In TCM, the condition of the disease changes according to constitution, referred to as transformation. After the body is affected by pathogenic Qi, due to the uniqueness of constitution, the pathological nature often undergoes different changes. For example, when affected by wind-cold pathogens, individuals with Yang-heat constitution often transform into heat, while those with Yin-cold constitution are prone to transform into cold. Similarly, when affected by dampness, individuals with Yang-heat constitution may transform dampness into heat, presenting with damp-heat symptoms, while those with Yin-cold constitution may transform dampness into cold, presenting with cold-damp symptoms. Due to the Yin-Yang nature and the strength and weakness of the Zang-Fu organs, the body can differentiate between cold, heat, dampness, and dryness in response to pathogenic factors.
2. The Transmission of Constitution and Pathogenesis: Different constitutions lead to different disease progression. In TCM, transmission refers to the changes and development trends of diseases. Transmission is not fixed; it varies from person to person. A robust constitution or mild pathogenic Qi can resist the pathogen, leading to spontaneous recovery. For example, in the case of a cold, if a patient recovers after more than seven days, it is because the period of the Yang channel has ended, and Zheng Qi has overcome the pathogen. If the pathogenic Qi is strong and the body has conditions for transmission, the disease can rapidly progress; for instance, in a cold, if the patient has a mild fever for six or seven days but the fever does not subside, and the patient is restless, it is because Zheng Qi cannot resist the pathogen, and the disease has transmitted from the Yang channel to the Yin channel. In summary, whether a disease transmits or not, although related to the strength of the pathogen and the appropriateness of treatment, mainly depends on constitutional factors.
In conclusion, the occurrence and development of diseases primarily depend on the patient’s constitutional characteristics (of course, this is closely related to the quality and quantity of the pathogenic factors). The “syndrome” has a temporal characteristic throughout the disease course; it is not fixed but changes with the progression of the disease. The “syndrome” often transforms based on constitution, which is one of the material bases for forming the “syndrome.” The so-called “different diseases with the same syndrome” and “same disease with different syndromes” are, to some extent, based on constitutional theory. Therefore, when observing the occurrence and development of diseases, we must grasp the patient’s constitutional characteristics and pay attention to the movement of Yin-Yang contradictions within the body under the influence of pathogenic factors, distinguishing between cold and heat, deficiency and excess, Yin and Yang, and exterior and interior.
4. Constitution and Syndrome Differentiation
Constitution is the foundation of syndrome differentiation; it determines the clinical syndrome types. Even with the same pathogenic factors or the same disease, due to the differences in patient constitution, the clinical syndrome types will differ in terms of Yin-Yang, exterior-interior, cold-heat, and deficiency-excess. For example, when affected by cold pathogens, some individuals may present with fever and chills, body aches, thin white tongue coating, and floating pulse, indicating an exterior wind-cold syndrome; while others may immediately show signs of cold limbs, poor appetite, abdominal pain, diarrhea, and a weak pulse, indicating a deficiency of spleen Yang. The former has a relatively strong constitution and Zheng Qi can resist the pathogen at the surface; the latter has a deficiency of Yang Qi, and Zheng Qi cannot overcome the pathogen, leading to the cold pathogen penetrating the Taiyin. Similarly, in the same region and period, colds may present differently due to different pathogenic factors and constitutions, leading to clinical types of wind-cold, wind-heat, and various combinations of dampness and heat. The determining factor for different syndromes in the same disease is not the pathogenic factor but the constitution. For instance, in the case of cold damage as discussed by Zhang Zhongjing, the transmission pathway generally goes from the Yangming to the Shaoyang and then to the three Yin channels. Why do some individuals transform from Jueyin to heat, while others transform from Shaoyin to cold? The reason lies in the fact that those who transform to heat have a deficiency of Yin, while those who transform to cold have a deficiency of Yang. This shows that the same pathogenic factor or disease can lead to different syndromes due to different constitutions. On the other hand, different diseases with the same syndrome are also related to constitution. Even with different pathogenic factors or diseases, if the patient’s constitution has commonalities in certain aspects, similar or identical clinical syndromes often appear. For example, both diarrhea and edema can present with symptoms of spleen and kidney Yang deficiency. This may be due to the fact that although the pathogenic factors or diseases are different, the constitution is the same, leading to similar syndromes. Thus, constitution is one of the physiological bases for forming the “syndrome,” and understanding constitution is an important basis for syndrome differentiation.
5. Constitution and Treatment
Constitution is an important basis for treatment. In the prevention and treatment of diseases, tailoring treatment according to constitution is not only an important aspect of individualized treatment but also a characteristic of TCM. In clinical practice, the same disease and the same treatment method may be effective for one person but not only ineffective for another but may even be harmful; the reason lies in the fact that the disease is the same but the individuals are different, and the constitutions are different, leading to different therapeutic effects. Constitution and treatment are closely related, and constitution determines treatment outcomes.
(1) Individualized Treatment
Constitutions vary in strength and weakness, and in coldness and heat. Therefore, it is essential to consider constitution when differentiating syndromes and treating. For example, individuals with a pale complexion and a plump body, belonging to a Yang deficiency constitution, are inherently cold and damp; if they are affected by cold and damp pathogens, they cannot be treated with hot and warming herbs like ginger and Atractylodes; if they are affected by damp-heat pathogens, they will have lingering difficulties in recovery and must be treated to promote Yang and transform dampness; using overly cool herbs will further block the dampness within and weaken Yang Qi. Conversely, individuals with a pale complexion and a thin body, belonging to a Yin deficiency constitution, are prone to internal heat, and dampness transforms into heat, harming body fluids; thus, their treatment must be distinctly different from that of Yang deficiency individuals. Therefore, although both Yang deficiency and Yin deficiency individuals may be affected by damp-heat pathogens, their treatment methods are vastly different. In summary, for individuals with Yang excess or Yin deficiency, caution should be exercised when using warming herbs that may harm Yin; for those with Yang deficiency or Yin excess, caution should be exercised when using cold herbs that may harm Yang.
Additionally, treatment should also consider factors such as age, gender, living conditions, and geographical environment that contribute to constitutional differences.
1. Age: The body’s Qi and blood, as well as the strength and weakness of the Zang-Fu organs, change with age, affecting the body’s response to pathogenic factors. Therefore, age is closely related to treatment. For example, children belong to the “young Yin and young Yang” constitution, and whether using warming or bitter cold herbs, treatment should be stopped once the disease is addressed. This is because bitter cold substances can easily deplete the vital energy of children, while warming substances can easily harm true Yin. Similarly, elderly individuals often have weakened kidney Qi and deficient middle Qi, making them susceptible to pathogens, and after falling ill, they often present with deficiency syndromes or a mix of deficiency and excess. Therefore, treatment must be approached with caution. As the Qing dynasty physician Ye Tianshi stated, treatment for elderly diseases should consider constitution, preserve true Qi, and be cautious of depletion.
2. Gender: Women have physiological characteristics that differ from men. Women are born with a liver constitution and often have insufficient blood; therefore, clinical treatment should pay special attention to whether female patients have symptoms of liver Qi stagnation or blood deficiency.
3. Living Conditions: Lifestyle habits and nutritional status greatly influence constitution. Generally speaking, excessive consumption of rich foods often leads to phlegm-dampness or damp-heat constitutions; excessive indulgence can harm true Yin and true Yang; frequent hunger and labor can lead to spleen and stomach deficiency, thus requiring differentiated treatment.
4. Geographical Environment: Different regions and lifestyles lead to differences in constitution; therefore, TCM emphasizes adapting treatment to local conditions.
(2) Different Treatments for the Same Disease, Same Treatments for Different Diseases
Due to constitutional differences, even the same disease can present with different syndromes, thus requiring different treatments. On the other hand, even if the pathogenic factors or diseases are different, if the patient’s constitution has commonalities in certain aspects, similar or identical syndromes often appear, thus requiring the same treatment.
(3) Medication Considerations
Due to the differences in Yin-Yang bias in constitution, treatment should consider constitution when prescribing medications. First, pay attention to the properties of the herbs. Generally speaking, individuals with Yin deficiency should use sweet, cold, sour, and moistening herbs, avoiding spicy, warming, bitter, and cold herbs; individuals with Yang deficiency should use herbs that tonify Yang and warm, avoiding bitter and cold herbs that drain fire; individuals with Qi deficiency should use herbs that tonify Qi and strengthen the source, avoiding those that deplete and exhaust. Second, pay attention to the dosage of herbs. Generally, larger doses are suitable for robust individuals, while smaller doses are suitable for thin and weak individuals. Those who are impatient may require larger doses for quick effects, while those who are more cautious may require moderate doses for gradual effects.
(4) Post-Treatment Care
After initial recovery or when approaching recovery, TCM places great importance on post-treatment care to promote recovery. This also falls within the scope of treatment. At this time, various measures are often required, including medication, diet, mental and psychological support, and lifestyle habits. The specific selection and application of these measures must vary according to the patient’s constitutional characteristics. For example, individuals with a dry-red constitution should be cautious with spicy and warming foods like dog meat, lamb, and longan after recovering from a heat illness; individuals with a sticky constitution should avoid greasy foods like turtle and tortoise, as well as sour and astringent substances like Schisandra and black plum after recovering from a major illness.
In summary, TCM constitutional theory, as an applied discipline, originates from clinical practice and ultimately serves clinical practice, developing from clinical experience. The contribution of TCM constitutional theory lies not only in life sciences but also in clinical medicine, as it reveals the relationship between human health and disease more comprehensively and fundamentally, thus providing stronger guidance for medical practice.
