The twenty first chapter is one of the most important chapters of Charaka Samhita Sutrasthana. It explains the process of obesity, its treatment, how to gain weight, importance of sleep and more. It is called as Ashtau Ninditeeya Adhyaya. Ashta means eight. Nindita means undesirable. It deals with eight types of undesirable body constitutions.
Eight undesirable constitutions
Following are the eight types of undesirable physical constitution.
Ati Deergha – too tall,
Ati Hrasva – too short,
Ati Loma – too hairy,
Aloma – hairless,
Ati Krishna – too black,
Ati Gaura – too white,
Ati Sthoola – too corpulent and
Ati Krisha – too emaciated. 
(The word undesirable should only be understood from the health perspective. The term undesirable in present context means, extra healthcare efforts are required to maintain good health of the above individuals. Very tall person is correlated to gigantism, very short person means dwarfism. In a normal colored family, if someone is born with abnormally excess white or black skin color, then they are grouped under ati krishna and ati gaura. This does not apply to generally tall or short or white or black skin colored persons).
Health issues due to obesity
Highly obese people have following health issues.
Ayusho Hrasa – Deficient in longevity, short life term,
Javoparodha – slow in movement
Krichra Vyavayata – Difficulty in intercourse
Daurbalya – weakness
Daurgandhya – body odor
Svedaabadha – excess sweating
Kshudha atimatram – excessive hunger
Pipasa Atiyoga – excessive thirst.
Causes for obesity
Ati Sampooranat – excess intake of food
Guru Madhura Ahara -heavy to digest, sweet foods,
Sheeta Snigdha Ahara – cooling and unctuous (oily) food,
Avyayamaat – due to lack of physical exercise,
Avyavaayaat – due to abstinence from sexual intercourse,
Divasvapnaat – due today sleeping,
Harsha Nityatvaat – uninterrupted cheerfulness, happy all the time,
Achintana – lack of mental exercise, lack of thinking
Beeja Svabhaavaat – heredity.
Reasoning for symptoms in obesity
In obese people, only Medo Dhatu (fat tissue) gets nourishment. Hence, other body tissues are deprived of nourishment. Hence, longevity is affected. The bodily movement is impaired due to the looseness, tenderness and heaviness of fats.
Due to deprived Shukra Dhatu (reproductive system), there will be difficulty in intercourse. It is also caused by less quantity of semen and obstruction of related channels.
Bad smell is caused by the inherent defect and nature of the fat tissue and also due to excessive sweating
As the fat is associated with Kapha and as it is fluidity, bulkiness and heaviness, the person cannot withstand physical exercise and it brings about excessive sweating.
Because of the sharp digestive power and the presence of excess Vata Dosha in digestive tract, there is excessive hunger and thirst. 
Pathophysiology of obesity
In obesity, Medo Dhatu obstructs the channels related to digestive system (Koshta). This results in obstruction of Vata Dosha in the digestive system.
It increases Agni (digestive fire, like wind increases fire) and dries up food in the stomach and intestines. Hence, food digestion speeds up increasing hunger. So the patient digests food quickly and becomes a voracious eater.
If he does not get the food on time, he becomes prone to serious disorders.
The Agni (digestive fire), influenced by Pitta and Vata Dosha get vitiated. They burn the food as the forest fire burns the forest. Hence the body weight increases.
Due to disproportionate increase of fat, diseases of very serious types are caused, all of a sudden, by Vata, etc. This may lead to instantaneous death.
Owing to an excessive increase of fat and muscle tissue, the buttock, abdomen and breast become pendulous and his strength is rendered disproportionate with his physical growth. Thus, the defects of the corpulent persons, their causes, signs and symptoms have been explained. [5-10]
Causes for emaciation
Causes for emaciation – lean person:
Rooksha Annapana – consumption of food and drinks that are dry in nature
Langhana – fasting for long periods of time
Pramitashana – taking very less quantities of food
Kriya Atiyoga – excessive Panchakarma therapies,
Shoka – grief,
Vega Nidra Vinigraha – suppression of the natural urges including sleep,
Rookshasya Udvartana – performing powder massage on a naturally dry person
Snana – repeated baths,
Prakruti – heredity,
Jara – old age,
Vikara Anushaya – continued illness
Krodha – anger
Features of emaciation
Features of very lean person:
Vyayama Asauhitya – cannot stand physical exercise,
Kshut, Pipasa Amaya, Aushadham – cannot stand intake of food in large quantity, hunger, thirst, diseases and drugs.
Na Sahate Ati Sheeta Ushna Maithuna – cannot stand excessive cold, heat and sexual acts.
Such emaciated persons are prone to
Pleeha – splenic diseases,
Kasa – cough, cold
Kshaya – muscle wasting,
Shwasa – dyspnoea, asthma
Gulma – abdominal tumor,
Arsha – piles, and diseases of the duodenum and small intestine.
Features of lean person:
Their buttocks, abdomen and neck are emaciated, veins are prominent underneath skin
The joints are prominently seen and the man appears to have bone and skin only. [10-15]
Comparative disadvantage of corpulence and emaciation
Both the types- high obesity or leanness patients suffer from diseases all the time.They are to be treated by slimming and nourishing therapies respectively. Of the two, leanness less harmful than obesity,though both of them are equally in need of treatment. When subjected to diseases, the volume of suffering in case of obese persons is far greater than in emaciated ones. [16-17]
Features of good physical health
Sama Mamsa pramana – proportionate musculature
Sama Samhana – compactness of the body
Druda indriya – strong sensory and motor
Cannot be overcome by the onslaught of diseases
Kshut Pipasa Atapa Saha – Ability to stand hunger, thirst, the heat of the sun,
Sheeta Vyayama Samsaha – Ability to stand cold and physical exercises.
Samapakta, Samajara – Ability to digest and assimilate food easily,
Sama Mamsa Upachaya – good muscular body.[18-19]
Principles of treatment for obese and emaciated persons:
Management of obesity
For reducing over corpulence the following are the prescriptions are suitable:
1. Diets and drinks that alleviate Vata and Kapha Dosha and which can reduce fat.
2. Rooksha, Ushna Teekshna Basti – Enema with drugs that are sharp, unuctuous and hot.
3.Rooksha Udvartana – powder massage with herbs having dry quality
4. Intake of Guduchi (Tinspora cordifolia), Musta (Cyperus rotundus), Triphala (Haritaki (Terminalia chebula Linn.), Bibhitaki (Terminalia belerica Roxb.) and Amalaka (Emblica officinalis Gaertn.))
5. Administration of Takrarista – buttermilk, fermented with spices
6. Administration of honey.
7. Intake of Vidanga (Embelia ribes Burm f.), Nagara (ginger), Yavaksara(Kshara prepared from Barley),Loha Bhasma with honey and powder of Yava – barley and Amla.
8. Administration of honey along with decoction of Bilvadi panchamula (roots of Bael, Oroxylum indicum, Gmelina arborea, Stereospermum suaveolens and Clerodendrum phlomidis)
9. Administration of Silajatu (asphaltum / mineral pitch).
10. Administration of the juice of Agnimantha (Clerodendrum phlomidis Linn. f.)
11. Intake of Prashatika (Setaria italica Beauv.), Priyangu (Callicara macrophylla), Syamaka (Echinochloa frumentacea Linn.), Yavaka (small variety of barley), Yava – Barley, Jurnahva (Sorghum vulgare Pers.), Kodrava (Paspalum scrobiculatum Linn.), Mudga (green gram), Kulattha (horse gram), Chakramudgaka (?), seeds of Adhaki (Cajanus cajan Millsp.) along with Patola (Trichosanthes cucumerina Linn.) and Amalaki (Indian gooseberry) as food,
12. Madhudhaka – combination of honey and water
13. Alcoholic preparations that help to reduce fat, muscle and Kapha may be used as after-food-drinks.
The above are to be prescribed in proper dosage for the reduction of obesity. One desirous of reducing obesity should indulge more and more in having less sleep, sexual act, physical and mental exercises. [21-28]
Management of leanness
Swapna – Sleep,
Harsha – joy,
Sukha Shayya – comfortable bed,
Manaso nivrutti, shama – contentment, tranquility of mind,
Abstinence from anxiety, sexual act and physical exercise,
Priya Darshana – pleasant sights and people,
Nava Anna – Intake of freshly harvested rice,
Nava Madya – fresh wine,
Gramya, Anupa and Audaka Mamsarasa – Meat soup of domestic, marshy and aquatic animals,
Well prepared meat, curd, ghee, milk, sugarcane, rice, Masha (black gram), wheat, sugar candy preparations,
Snigdha Madhura Basti – enema consisting of oily and sweet drugs,
Taila Abhyanga – regular oil massage,
unctuous unction bath, use of scents and garlands, use of white apparel, elimination of Dosas in time and administration of rejuvenating and aphrodisiac drugs remove emaciation and bring out nourishment in the body.
Freedom from anxiety about any work, intake of nourishing diet and adequate sleep makes the fatty like a boar. [29-34]
Physiology of Sleep
When the mind including sensory and motor organs is exhausted and they dissociate themselves from their objects, then the individual sleeps. 
Effect of Sleep
Happiness, misery, nourishment, emaciation, strength, weakness, virility, sterility, knowledge, ignorance, life and death all these occur depending on the proper or improper sleep.
Like the night of destructions, untimely and excessive sleep and prolonged vigil (waking up at night), take away both happiness and longevity. The same sleep, if properly enjoyed brings about happiness and longevity in human beings as the real knowledge brings about Siddhi (spiritual power) in a Yogi.
Indications of day sleep
Sleeping during the day time in all seasons is prescribed for those who are exhausted by singing, study, alcoholic drinks, sexual acts, Panchakarma therapy, carrying heavy weight, walking long distance.
Those suffering from indigestion, injuries,muscle wasting, thirst, diarrhea, colic pain, dysponea (as in Asthma), hiccup, leanness, insanity, those who are too old, too young, weak and emaciated those injured by fall and assault, those exhausted by journey by a vehicle, vigil, anger, grief and fear, and those who are accustomed to day sleep.
By this the equilibrium of Dhatus and strength are maintained and the Kapha nourishes the organs and ensures longevity.
In summer season nights become shorter and Vata gets aggravated in the body due to the absorption of fluid (Adana). Therefore, during this season, sleep during day time is prescribed for all. [39-43]
Contraindications of day sleep
Sleeping during day time in the seasons other than summer is not advisable as it causes vitiation of Kapha and Pitta.
Obese persons, those who are addicted to taking oily foods, those with Kapha body type,those suffering from diseases due to the vitiation of Kapha and those suffering from Dooshivisha (artificial poisoning) should never sleep during day time.
If one violates the prescription regarding sleep during the day time, he would subject himself to
Halimaka (serious type of jaundice),
Shirashoola – headache,
Agninasha – loss of digestion strength,
Pralepo Hrudayasya – coating of heart region, feeling of heaviness,
Shopha – oedema,
Aruchi – anorexia,
Hrullasa – nausea,
Peenasa – rhinitis,
Ardhavabhedhaka – hemicrania, migraine,
Kotha, Pidaka, Kandu – urticaria, eruption, abscess, pruritus,
Tandra – drowsiness,
Kasa – cough,
Galaamaya – diseases of the throat,
impairement of the memory and intelligence, obstruction of the channels of the body, fever, weakness of sensory and motor organs and enhancement of the toxic effects of artificial poisons (Gara Visha).
So one should keep in view the merits and demerits of sleep in various seasons and situations in order that it may bring happiness to him. [44-49]
Effect of ratri jagarana
Vigil during night causes roughness in the body sleep during day time causes increased oiliness.
Sleeping in sitting posture does neither cause roughness nor unctuousness. 
The role of sleep in obesity
Like proper diet, proper sleep is also essential for the maintenance of the body. Obesity and emaciation are specially conditioned by proper or improper sleep and diet. 
Methods to induce good sleep
Abhyanga – massage,
Utsadana – body massage,
bath, intake of soup of domestic marshy and aquatic animals, rice with curd, milk, unctuous substance and alcohol, psychic pleasure, smell of scents and hearing of sounds of one’s own taste, Samvahana (rubbing the body by hand), application of soothing ointment to the eyes, head and face, comfortable bed and home and proper time. [52-54]
Causes of Insomnia
Elimination of Dosas from the body and head through Panchakarma therapies,
Fear, anxiety, anger, herbal smoke, physical exercise, blood letting (Rakta Mokshana), fasting, uncomfortable bed, predominance of Satva and suppression of Tamas help in overcoming excess sleep.
The above-mentioned factors along with overwork, old age, diseases, specially these due to the vitiation of Vata like colic pain, etc. are known to cause sleeplessness even in normal individuals. Some have less sleep by nature. [55-57]
Classification of sleep
Types of sleep
1.Tamo Bhava – Caused by Tamas
2. Shleshma Samudbhava – Caused by (vitiated) Kapha
3. Mana Shrama Sambhava – Caused by mental exertion
4. Shareera shrama sambhava – Caused by physical exhaustion
5. Agantuka – caused by external causes such as injury,
6. Vyadhi anuvartini – Caused as a complication of other diseases like Samnipata Jvara, etc. and
7. Ratri Svabhavaja – Caused by the very nature of the night (physiological sleep). 
Good and bad sleep
The sleep caused by the nature of the night is the sleep par excellence This is known as Bhutadhatri (that nurses all the living beings). The one caused by Tamas is the root cause of all sinful acts. The remaining types are to be treated as diseases. 
Lord Punarvasu on the chapter on Eight types of Undesirable Constitutions has explained the following.
1. Enumeration of undesirable constitutions
2. The two most undesirable types of persons
3. Cause of undesirability
4. Demerits of undesirable persons
5. Their treatment
6. Indications and contra-indications of sleep depending upon the nature of the individual and time
7. Treatment of excessive sleep and sleeplessness
8. Factors that are responsible for causation of sleep and
9. Types and effects of sleep. [60-62]
Thus ends the twenty-first chapter on eight types of Undesirable Constitutions of the Sutra section of Agnivesha’s work as redacted by Charaka.