李东垣以饮食劳倦为内伤不足之病，谓因饥饱不调伤损脾胃所致。盖人之所借以生者，
脾胃为本，必赖饮食滋养。若调养失宜，劳役过伤，失其所养，则脾胃气虚，不能升达，陷郁为
热，亦与外感发热相似。人多误以内伤混作外感处治，故东垣着《脾胃内伤论》，制以补
中益气汤，非为饮食有余之立法也。王安道谓其不着饮食有余之伤，以为白璧微瑕之诮，
其亦责备之过也。然则内伤专言其虚，而胃气下陷主于升补，不可混言。饮食有余之伤，可
用消导。今以有余之伤，别为脾胃一门，不得附于劳倦不足中也。学人宜于各类求之。
黄帝曰∶阴虚生内热，奈何？岐伯曰∶有所劳倦，谷气衰少，形气不盛，下脘不通，
上焦不行，胃气热，
热气蒸胸中，故内热。
又曰∶病生于阴者，得之饮食居处，阴阳喜怒。
太阴阳明论曰∶阳者，天气也，主外；阴者，地气也，主内。故阳道实，阴道虚。犯贼
风虚邪者，阳受之；饮食不节，起居不时者，（即内伤也。）阴受之。阳受之则入六腑，阴受
之则入五脏。入六腑则身热，不时卧，上为喘呼；入五脏则腹满闭塞，下为飧泄，久为肠 。
此见内伤外感阴阳虚实之不同也，岂容不辨内外虚实之证而处治哉？
平人气象篇曰∶人以水谷为本，故人绝水谷则死也。
通评虚实篇曰∶头痛耳鸣，九窍不利，肠胃之所生也。
又曰∶阴之所生，本在五味；阴之五宫，伤在五味。
李束垣曰∶历考《内经》，元气之充足，皆由脾胃之气无所伤，而后能滋养元气。
若胃气之本弱，饮食自倍，则脾胃之气既伤，而元气亦不能充，而诸病由生也。《内经》之旨，
皎如日星，犹恐后人有所未达，故《灵枢经》中复申其说。经云∶水谷入口，其味有五，
各注其海，津液各走其道。胃者，水谷之海。其输上在气街，下至三里。水谷之海有余，
则腹满；水谷之海不足，则饥不受谷食。人之所受气者，谷也。谷之所注者，胃也。胃者，
水谷气血之海也。海之所行云气者，天下也。胃之所出气血者，经隧也。经隧者，五脏
六腑之大络也。又云∶五谷入于胃也，其糟粕津液宗气，分为三队。故宗气积于胸中，
上于喉咙，以贯心肺，而行呼吸焉。荣气者，泌其津液，注之于脉，化而为血，以荣四末，
内注五脏六腑，以应刻数焉。卫者，出其悍气之 疾，而行于四末分肉皮肤之间而不休
者也。又云∶中焦之所出，亦并胃中，出上焦之后。此所受气者，泌糟
粕，蒸津液，化为精微，上注于肺脉，乃化而为血，以奉生身，莫贵乎此。圣人谆复其辞而
不惮其烦者，仁天下后世之心亦倦倦矣。故夫饮食失节，寒温不适，脾胃乃伤。此因喜怒忧
恐损耗元气，资助心火。火与元气不两立，火胜则乘其土位，此所以病也。
生气通天论云∶苍天之气，清净则志意治。顺之则阳气固，虽有贼邪，弗能害也，
此因时之序。故圣人传精神，服天气，而通神明。失之则内闭九窍，外壅肌肉，卫气散解，此
谓自伤，气之削也。阳气者，烦劳则张，精绝，辟积于夏，使人煎厥。目盲不可以视，耳闭
不可以闻，溃溃乎若坏都。故苍天之气贵清净，阳气恶烦劳。病从脾胃生者，一也。五常政
大论云∶阴精所奉其人寿，阳精所降其人夭。阴精所奉，谓脾胃既和，谷气上升，春夏令行，
故其人寿。阳精所降，谓脾胃不和，谷气下流，收藏令行，故其人夭。病从脾胃生者，二也。
六节脏象篇云∶脾胃大肠小肠三焦膀胱者，仓廪之本，荣之居也，名曰器，能化糟粕，转
味而出入者也。其华在唇四白，其充在肌，其味甘，其色黄。此至阴之类，通于土气。凡十一
脏皆取决于胆也。胆者，少阳春升之气。春气升则万化安。故胆气春升，则余脏从之。
胆气不升，则飧泄肠僻，不一而起矣。病从脾胃生者，三也。经曰∶天食人以五气，地食
人以五味。五气入鼻，藏于心肺，上使五色修明，音声能彰。五味入口，藏于脾胃。味有
所藏，以养五气。气和而生，津液相成，神乃自生。此谓之气者，上焦开发，宣五谷味，熏肤充身
泽毛，若雾露之溉。气或乖错，人何以生？病从脾胃生者，四也。
岂特四者，至于经论天地之邪气，感则害人五脏六腑，及形气俱虚，乃受外邪，不因
虚邪，贼邪不能独伤人，诸病从脾胃而生明矣。圣人旨意，重见叠出，详尽如此，且垂戒云∶法于阴阳
，和于术数，饮食有节，起居有常，不妄作劳，故能形与神俱，而尽终其天年，度百岁乃去。由是言之，饮食起居
之际，可不慎哉？
李东垣认为，饮食和劳倦是导致内伤不足类疾病的病因，他主张这是由于饥饱不调损伤了脾胃所致。大概人赖以生存的根本在于脾胃，必须依赖饮食来滋养。如果调养不当，过度劳累导致身体受损，失去了应有的滋养，那么脾胃之气就会虚弱，无法升发通达，郁滞而化热，这种发热症状与外感发热相似。人们常常错误地将内伤当作外感来治疗，所以李东垣撰写了《脾胃内伤论》，制定了补中益气汤，这并不是为了治疗饮食有余（即饮食积滞）的病证而设立的立法。王安道批评他没有论述饮食有余造成的伤害，认为这是白璧微瑕的缺憾，但这恐怕是责备过当了。然而，内伤主要论述的是虚证，胃气下陷的治疗关键在于升提补益，不能混淆而言。对于饮食有余造成的伤害，可以使用消食导滞的方法。现在将饮食有余的伤害单独列为脾胃门中的一类，不得附属于劳倦不足之中。学习者应当在各类病证中分别寻求理解。
黄帝问道：阴虚产生内热，是怎么回事？岐伯回答说：由于过度劳倦，谷气衰少，形体之气不盛，下脘不通畅，上焦不能宣发，导致胃气生热，热气熏蒸于胸中，所以产生内热。
又说：疾病生于阴分的，是由于饮食、居处、阴阳失调以及喜怒情绪等因素引起的。
《素问·太阴阳明论》说：阳，代表天气，主司外部；阴，代表地气，主司内部。所以阳道多实，阴道多虚。遭受贼风虚邪侵袭的，阳分先受之；饮食不节制，起居不规律的，（这就是内伤），阴分先受之。阳分受邪则传入六腑，阴分受邪则传入五脏。邪入六腑则出现身热，不能按时卧睡，向上表现为喘息呼叫；邪入五脏则腹部胀满闭塞，向下表现为完谷不化的泄泻，日久发展为肠澼（痢疾）。这显示了内伤和外感在阴阳虚实方面的不同，怎么可以不分辨内外虚实的证候就进行治疗呢？
《素问·平人气象论》说：人以水谷为根本，所以人断绝水谷就会死亡。
《素问·通评虚实论》说：头痛耳鸣，九窍不利，是由肠胃的问题产生的。
又说：阴精的产生，根本在于五味；阴精的五脏，损伤也在于五味。
李东垣说：遍考《内经》，元气的充足，都是因为脾胃之气没有受到损伤，然后才能滋养元气。如果胃气本来虚弱，饮食过量加倍，那么脾胃之气既已受伤，元气也不能充盈，各种疾病由此产生。《内经》的宗旨，像日月星辰一样明亮，还担心后人有所不理解，所以在《灵枢经》中再次申述这一观点。经文说：水谷入口，其味道分为五类，各自注入相应的海穴，津液各自运行其道。胃，是水谷之海。它的输注穴位上部在气街，下部至足三里。水谷之海有余，则腹部胀满；水谷之海不足，则饥饿却不想进食。人所禀受的气，来源于谷气。谷气所灌注的地方，是胃。胃，是水谷气血之海。海中运行的云气，就像天下的风气一样。胃所输出的气血，通过经隧输送。经隧，是五脏六腑的大络脉。又说：五谷进入胃中，其糟粕、津液、宗气，分为三队。所以宗气积聚在胸中，上行至喉咙，贯通心肺，以推动呼吸。营气，分泌其津液，注入脉中，转化为血液，以营养四肢末端，向内注入五脏六腑，以应合刻漏的时间节律。卫气，出于其剽悍滑疾之气，运行于四肢、分肉和皮肤之间，不停息。又说：中焦所发出的气，也并行于胃中，出自上焦之后。这里所受的气，分离糟粕，蒸腾津液，化为精微，向上注入肺脉，进而化为血液，以奉养全身，没有比这更宝贵的了。圣人反复叮咛而不怕麻烦，是为了对天下后世仁爱之心殷切啊。所以饮食失节，寒温不适，脾胃就会受伤。这是因为喜怒忧恐损耗元气，资助心火。火与元气不两立，火胜则乘袭脾土之位，这就是生病的原因。
《素问·生气通天论》说：苍天的气候，清净则人的志意安定。顺应它则阳气固密，虽然有贼邪，也不能伤害，这是顺应时序的结果。所以圣人保养精神，顺承天气，从而通晓神明。违背它则内部九窍闭塞，外部肌肉壅滞，卫气散漫解怠，这叫做自我伤害，是元气的削弱。阳气，烦劳过度则亢张，精血枯竭，累积到夏季，使人发生煎厥。眼睛失明不能视物，耳朵闭塞不能听声，混乱不堪如同堤坝崩溃。所以苍天之气贵在清净，阳气厌恶烦劳。这是病从脾胃生的第一种情况。《素问·五常政大论》说：阴精上奉于人，人长寿；阳精下降于人，人短命。阴精上奉，是说脾胃调和，谷气上升，春夏的生发令行，所以人长寿。阳精下降，是说脾胃不和，谷气下流，收藏的令行，所以人短命。这是病从脾胃生的第二种情况。《素问·六节脏象论》说：脾胃、大肠、小肠、三焦、膀胱，是仓廪之本，是营气居留的地方，名叫器，能转化糟粕，转输五味而出入。其荣华表现于口唇四周，其充养在于肌肉，其味属甘，其色属黄。这是至阴的一类，通应于土气。凡十一脏都取决于胆。胆，是少阳春升之气。春气升发则万物安和。所以胆气春升，则其余脏腑随之。胆气不升，则完谷不化的泄泻、肠僻等病，不一而足地发生了。这是病从脾胃生的第三种情况。经文说：天给人提供五气，地给人提供五味。五气从鼻吸入，藏于心肺，向上使面色光泽，声音洪亮。五味从口摄入，藏于脾胃。味道有所藏留，以滋养五气。气机调和则生命产生，津液相互成就，神气自然生成。这所说的“气”，是指上焦开发，宣发五谷的味道，熏肤充身泽毛，像雾露灌溉一样。气如果乖错失常，人怎么能生存？这是病从脾胃生的第四种情况。
岂止这四种情况，至于经络论述天地间的邪气，感受了则伤害五脏六腑，以及形气俱虚的时候，才接受外邪，如果不是虚邪，贼邪不能单独伤人，诸病从脾胃而生是显而易见的。圣人的旨意，重见叠出，详尽如此，并且留下告诫说：效法阴阳，运用术数，饮食有节制，起居有常规，不妄加劳作，所以能形神兼备，尽享天赋寿命，度过百岁才离去。由此说来，在饮食起居方面，能不谨慎吗？
Li Dongyuan considered that diet and fatigue are the causes of internal injury deficiency diseases, asserting that they result from damage to the Spleen and Stomach due to irregular eating. Generally, the foundation of human life lies in the Spleen and Stomach, which must rely on dietary nourishment. If proper care is neglected and overwork causes excessive damage, leading to a loss of nourishment, the Qi of the Spleen and Stomach becomes deficient and cannot ascend and diffuse. This stagnation transforms into heat, presenting symptoms similar to fever caused by external contraction. People often mistakenly treat internal injury as external contraction, so Li Dongyuan wrote "Treatise on Internal Injury of the Spleen and Stomach" (Pi Wei Nei Shang Lun) and formulated Buzhong Yiqi Tang (Tonify the Middle and Augment the Qi Decoction). This was not legislated for treating conditions of dietary excess (food stagnation). Wang Andao criticized him for not addressing injuries caused by dietary excess, regarding it as a slight flaw in an otherwise perfect jade, but this may be overly harsh criticism. Nevertheless, internal injury primarily discusses deficiency patterns; the treatment for sinking of Stomach Qi focuses on lifting and tonifying, and should not be confused with other types. For injuries caused by dietary excess, methods of digestion and guiding out can be used. Now, injuries from dietary excess are classified separately in the Spleen and Stomach section and should not be attached to those caused by fatigue and deficiency. Students should seek understanding within each respective category.
The Yellow Emperor asked: How does Yin deficiency generate internal heat? Qibo answered: Due to excessive fatigue, the Qi derived from grains declines, and the Qi of the form is not robust. The lower Jiao becomes obstructed, and the Upper Jiao fails to disseminate. Heat arises in the Stomach, steaming the chest, thus generating internal heat.
It is also said: Diseases originating from Yin are caused by diet, living conditions, imbalances of Yin and Yang, and emotions such as joy and anger.
The Treatise on Taiyin and Yangming states: Yang represents Heaven's Qi, governing the exterior; Yin represents Earth's Qi, governing the interior. Thus, the Path of Yang tends toward Excess, while the Path of Yin tends toward Deficiency. Those afflicted by treacherous winds and empty pathogens first affect Yang; those affected by unregulated diet and irregular起居 (daily routine)—which constitute internal injury—first affect Yin. When Yang is affected, the pathogen enters the Six Fu Organs; when Yin is affected, it enters the Five Zang Organs. Entering the Six Fu Organs results in body fever, inability to sleep at appropriate times, and upward manifestations like panting and calling; entering the Five Zang Organs results in abdominal fullness and obstruction, downward manifestations like undigested stool diarrhea, and if prolonged, intestinal dysentery. This demonstrates the differences in Yin-Yang and Excess-Deficiency between internal injury and external contraction. How can one prescribe treatment without distinguishing between internal/external and excess/deficiency patterns?
The Chapter on the Normal Person's Qi and Pulse States: Humans take water and grain as their root; therefore, if humans cut off water and grain, they die.
The Chapter on Thorough Evaluation of Excess and Deficiency States: Headache, tinnitus, and dysfunction of the nine orifices are generated by the intestines and stomach.
It also states: The generation of Yin essence originates from the five flavors; the five palaces of Yin are damaged by the five flavors.
Li Dongyuan stated: Examining the Neijing thoroughly, the sufficiency of Yuan Qi depends entirely on the Spleen and Stomach Qi being uninjured, thereby nourishing Yuan Qi. If the root of Stomach Qi is weak and food intake doubles, the Qi of the Spleen and Stomach is injured, Yuan Qi cannot be filled, and various diseases arise. The purport of the Neijing is as bright as the sun and stars. Fearing later generations might not fully understand, the Ling Shu Jing reiterates this theory. The classic says: Water and grain enter the mouth, their flavors divide into five categories, each pouring into their respective seas, with fluids taking their own pathways. The Stomach is the Sea of Water and Grain. Its transport points are above at Qichong (St30) and below at Zusanli (ST36). If the Sea of Water and Grain has excess, there is abdominal fullness; if it has deficiency, there is hunger but an inability to accept food. The Qi received by humans comes from grain. The place where grain pours is the Stomach. The Stomach is the Sea of Water, Grain, Qi, and Blood. The clouds and Qi circulating in the sea are like the winds of the world. The Qi and Blood exiting the Stomach travel through the meridians. The meridians are the great collaterals of the Five Zang and Six Fu Organs. It also says: When five grains enter the Stomach, their dregs, fluids, and Zong Qi divide into three groups. Thus, Zong Qi accumulates in the chest, ascends to the throat, penetrates the Heart and Lungs, and governs respiration. Ying Qi secretes its fluids, injects them into the vessels, transforms into blood, nourishes the four extremities, and internally injects into the Five Zang and Six Fu Organs, corresponding to the timekeeping of clepsydrae. Wei Qi issues forth from its fierce, rapid Qi, moving continuously among the four extremities, muscles, and skin. It also says: The Qi issuing from the Middle Jiao also runs alongside the Stomach, emerging after the Upper Jiao. The Qi received here separates dregs, steams fluids, transforms into refined essences, pours upward into the Lung vessels, then transforms into blood to nourish the living body. Nothing is more precious than this. The Sages repeat these words tirelessly, driven by profound benevolence towards future generations. Therefore, irregular diet and inappropriate cold or warmth injure the Spleen and Stomach. This occurs because joy, anger, sorrow, and fear deplete Yuan Qi and assist Heart Fire. Fire and Yuan Qi cannot coexist; if Fire prevails, it attacks the Earth position (Spleen/Stomach), causing disease.
The Chapter on Living Qi Connecting with Heaven states: The Qi of the blue sky is pure and clear, regulating one's will and intent. Following it consolidates Yang Qi; even if treacherous pathogens exist, they cannot harm. This follows the order of seasons. Thus, sages conserve spirit, serve Heaven's Qi, and communicate with divine illumination. Deviating from this causes internal closure of the nine orifices, external congestion of muscles, and dispersion of Wei Qi. This is called self-injury, the depletion of Qi. Yang Qi, when subjected to烦劳 (mental/physical exertion), expands excessively; essence is exhausted. Accumulating into summer, this leads to Jian Jue (Frying Collapse). Eyes become blind, unable to see; ears become closed, unable to hear. Chaos ensues like a breached dam. Thus, Heaven's Qi values purity, and Yang Qi abhors exertion. This is the first way diseases originate from the Spleen and Stomach.
The Chapter on Great Regularity of the Five Constants states: Where Yin essence is offered upwards, people live long; where Yang essence descends downwards, people die young. "Yin essence offered upwards" means the Spleen and Stomach are harmonious, grain Qi ascends, and the Spring-Summer commands execute, hence longevity. "Yang essence descending downwards" means the Spleen and Stomach are disharmonious, grain Qi flows downward, and the Autumn-Winter commands execute, hence early death. This is the second way diseases originate from the Spleen and Stomach.
The Chapter on Six Sections and Viscera Manifestations states: The Spleen, Stomach, Large Intestine, Small Intestine, San Jiao, and Bladder are the roots of the granary, the residence of Ying Qi, named "vessels," capable of transforming dregs and transporting flavors in and out. Their brilliance manifests in the lips and surrounding area; their substance fills the muscles; their flavor is sweet; their color is yellow. These belong to Supreme Yin, connecting with Earth Qi. All eleven organs depend on the Gallbladder. The Gallbladder possesses the ascending Qi of Shaoyang Spring. When Spring Qi ascends, all transformations are peaceful. Thus, when Gallbladder Qi ascends in spring, the remaining organs follow. If Gallbladder Qi does not ascend, undigested diarrhea and intestinal disorders arise incessantly. This is the third way diseases originate from the Spleen and Stomach. The classic says: Heaven feeds humans with five Qi, Earth feeds humans with five flavors. Five Qi enter via the nose, store in the Heart and Lungs, making complexion lustrous and voice resonant. Five flavors enter via the mouth, store in the Spleen and Stomach. Flavors are stored to nourish the five Qi. Harmonized Qi generates life; fluids complement each other; Shen naturally arises. This "Qi" refers to the Upper Jiao opening and disseminating, promoting the flavors of five grains, warming the skin, filling the body, and moistening hair, like mist and dew. If Qi is disordered, how can humans survive? This is the fourth way diseases originate from the Spleen and Stomach.
Are there only these four cases? Regarding the classics discussing heaven and earth's pathogens, upon contact, they harm the Five Zang and Six Fu Organs. Only when both form and Qi are deficient does one accept external pathogens. Without deficiency pathogens, treacherous pathogens cannot independently harm humans. It is clear that many diseases originate from the Spleen and Stomach. The Sage's intent appears repeatedly, detailed thus, and leaves warnings: Follow Yin and Yang, harmonize with techniques and numbers, regulate diet, maintain regular routines, avoid reckless labor. Thus, form and Shen remain united, completing one's natural lifespan, reaching a hundred years before passing. From this perspective, can one not be cautious regarding diet and daily routine?