Ahara vidhi literally means method of taking diet. It includes diet and dietary guidelines.The concept of diet in Ayurveda has a broader view beyond ingestion of food. Unlike modern dietetics, which is restricted to concept of calorie consumption, Ayurveda recommends methods of taking food, its quality and quantity based upon individual’s capacity to digest (agni). In this article, various aspects of concept of diet in Ayurveda are discussed.
|Section/Chapter/topic||Health / Ahara vidhi /Dietary guidelines|
|Reviewed by||Basisht G.|
|Affiliations||Charak Samhita Research, Training and Development Centre, I.P.G.T.& R.A., Jamnagar|
|Date of first publication:||July 14, 2020|
‘Anna’ and ‘ahara’ are the two Sanskrit terms applied to denote food and diet. Anna is ingested or eaten through mouth. The term ‘ahara’ includes all substances that are taken in by humans by various routes, including sense organs and mind too.
Broader views of nutrition of body, mind, sense organs and soul are denoted by applying the term ‘ahara’. The researchers observe that when food enters mouth and passes through the digestive system, it sends a multitude of interacting signals to the brain, loaded with sensory, nutritive, and other information.  Thus, the digestion and metabolism is not limited to ingestion of food only; but it is affected by how the brain and nervous system receives and processes the information too. This article describes classification of food, quantity of food, dietary guidelines and important factors influencing digestive health.
Classification of food
I. According to fundamental composition of food
Digestion of food depends upon the innate properties of food. There are mainly two categories of food according to their effect on digestion:
- Light to digest or quickly digestible food items(laghu)
- Heavy to digest or slowly digestible food items (guru)
The light to digest substances have a predominance of the qualities of vayu and agni mahabhuta. Therefore, the light food-articles are stimulants of agni owing to their innate quality, and are said to be less harmful even if they are eaten to a surfeit. The heavy to digest substances have predominant qualities of prithvi and jala mahabhuta. They do not stimulate agni due to their properties. Thus, they can cause harm if taken in excess quantity. Strong digestive strength achieved by physical exercise is needed to digest them.
Examples of light to digest foods:
Shali rice (Oryza sativum), shashtika rice (variety of Oryza sativum), radiata green gram (mudga Vigna), meat of common quail, gray partridge, antelope, rabbit, wapiti, Indian sambar deer, and such other food-articles are light to digest.
Examples of heavy to digest foods:
Preparations of flour (pastry), sugar-cane juice and sugar preparations, milk and milk preparations, sesame (tila, Sesamum indicum), black gram (masha, Vigna mungo), flesh of aquatic animals, marshy land animals are inherently heavy to digest foods. [Cha.Sa.Sutra Sthana 5/5]
II. According to sources of food
All the food and beverages are categorized under twelve classes according to their source and form. These classes are corn (shuka dhanya), pulses (shami dhanya), meat (mamsa varga), vegetable (shaka varga), fruits (phala varga) , greens (harita varga) , wines(madya varga), water (jala varga), milk and its products (dugdha varga), sugarcane and its products (ikshu varga ), cooked food (kritanna varga) and adjuvant of foods (ahara yogi varga). Their taste, potency, post-digestive qualities and specific properties are important for preservation of health and management of disease. [Cha.Sa.Sutra Sthana 27/6-7]
According to dietary guidelines, the healthy Mediterranean style eating pattern is categorized into following five groups:
- Vegetables including dark green, red and orange, legumes (beans and peas), starchy vegetables and other vegetables
- Grains including whole grains and refined grains
- Dairy products
- Protein food including sea food, meats, poultry, eggs, nut seeds and soy seeds
Based upon calorie needs of individuals in population of United States ranging from minimum 1000 calories to maximum 3200 calories, twelve calorie groups are formed. Specific quantity of each type of food is recommended in each group. [USA Dietary Guidelines page 80-83]
III. According to forms of food
Different types of wholesome foods are categorized in four categories like
- Eatables (ashita)
- Drinkables (peeta)
- Lickables (leedha)
- Masticables (khadita)
IV. According to effects of food
The food can be divided in two categories according to its naturally beneficial and harmful effects to human being:
- Wholesome (pathyatama)
- Unwholesome (apathyatama) [Cha.Sa.Sutra Sthana25/37]
General properties of food
Each food item has a specific taste(rasa), property (guna), potency (veerya), and post digestion effect or metabolite (vipaka). A particular food has a specific effect (prabhava) beyond these properties. All the effects are seen due to either of these properties. Atreyabhadrakapyiya Adhyaya [Cha.Sa.Sutra Sthana26]
Proper quantity of food
One must take food in proper quantity. The quantity of food is person specific and depends on the strength of his/her agni (digestive power). The proper quantity of food is digested in due time without disturbing the equilibrium. [Cha.Sa.Sutra Sthana 5/3-4]
Dietary guidelines advise to take food according to energy requirement based upon age, gender, physiological conditions like pregnancy, lactation and level of physical activity. The goal is to maintain ideal body weight and optimal nutrition status. 
Proportion of heavy and light to digest food
The right quantity always depends upon the substance itself. Based on the food-article itself, it is advised that heavy to digest articles should be taken up to one third to one half of the saturation point (of capacity of stomach); The remaining proportion shall be filled with light to digest food. Neither heavy to digest not light ones should be taken in surfeit in order to maintain the strength of agni. [Cha.Sa.Sutra Sthana 5/7]
Eating variety of food (sarva graha) or single substance (parigraha)
The healthy eating pattern includes taking all types of foods together (sarva graha) and not a particular substance (parigraha) at one time. This affects the digestion and metabolism of food. [Cha.Sa.Vimana Sthana 1/22.4] For example, eating a dish containing all food items like roti, curry, dal, rice together has a different effect than eating only rice at one time. This also affects the overall nutrition status.
Three divisions of stomach
The total capacity of stomach can be divided in three functional parts for deciding the proper quantity of diet. One part of solid, one for liquids and third part can be left empty for movement of dosha. Therefore, one shall fill stomach up to maximum of two third of its capacity with equal proportionate ingestion of solid foods and liquid beverages. This preserves health and prevents diseases. [Cha.Sa.Vimana Sthana 2/3]
Assessment of proper quantity of food
- The assessment of proper quantity of food can be done by observing following signs after consumption of food:
- No feeling of undue pressure in abdomen due to ingested food
- No feeling of heaviness due to food or feeling of lightness
- No obstruction in functioning of heart or no congestion or heaviness in chest and flanks
- Feeling of satiety and nourishment in senses
- No feeling of hunger and thirst
- Comfortable and ease in movements while standing, sitting, walking, exhaling, inhaling, laughing and talking
- Normal digestion of food taken in morning and evening
- Enhancement of strength, complexion, and nourishment of tissues. [Cha.Sa.Vimana Sthana 2/6]
Symptoms of taking less or insufficient quantity of food
- Reduction in strength, complexion and nourishment of body tissues,
- Lack of satiety, dis-satisfaction,
- Altered peristalsis and abnormal functioning of vayu
- Impairments in vital functions, quality of body tissues (sara), sexual stamina (virility) and ojas (vitality)
- Impairment of the body, mind, intellect, and sense organs
- Feeling of in-auspiciousness or dirtiness
- Susceptibility to disorders of vata
Signs of taking excess quantity of food
- Sudden aggravation of all three dosha in abdomen
- Either obstruction of all the movements in the abdomen (sluggish bowel)
- or Sudden elimination through upper and lower channels of the alimentary tract (cholera)
- Aggravation of Vata causes colic pain, distension of the abdomen, body ache, dryness of the mouth, fainting, giddiness, variability in digestive power, rigidity in flanks, back and waist and contraction (spasm) and hardening of vessels.
- Aggravation of Pitta causes fever, diarrhoea, burning sensation inside body, thirst, intoxicated state, giddiness and delirium.
- Aggravation of Kapha causes vomiting, anorexia, indigestion, fever with cold, laziness and heaviness in the body. [Cha.Sa.Vimana Sthana 2/7]
Benefits of proper quantity diet
The food taken in right quantity certainly provides strength, complexion, happiness and longevity to the person; without disturbing the normalcy. [Cha.Sa.Sutra Sthana 5/8] It maintains equilibrium of dosha, normal digestion and metabolism (agni), easily passes down through the bowels, and gets digested without discomfort. [Cha.Sa.Vimana Sthana 1/25.3]
If food is taken in excess quantity, it leads to disorders due to over nutrition and vice versa. A large number of disorders including obesity, cardiovascular diseases including coronary artery disease and hypertension, diabetes, cerebrovascular stroke are caused due to over nutrition. Malnutrition results in Kwashiorkor/Marasmus, iron deficiency anaemia, stunting, wasting especially in children.
Sequence of eating food items
The food with sweet taste shall be taken in the beginning followed by those with sour and salty taste. The food with other tastes like pungent, bitter and astringent shall be taken at last. According to the source of food, fruits should be taken in the beginning followed by liquid gruel (peya). Then the variety of solid eatables (bhojya and bhakshya) can be taken. The best fruit to be taken at the beginning is Indian gooseberry (amalaka). [Su.Sa.Sutra Sthana 46/460-463]
This sequence of taking food is based upon the status of digestive factors (agni) and post digestive effects (vipaka) of food. The sweet food items are generally heavy to digest and can be digested easily when taken at first in the presence of peak strength of digestive power (agni). The first phase of digestion after taking meals is dominated by effect of sweet taste (madhura avastha paka), followed by sour taste (amla avastha paka) and ended by pungent taste (katu avasthapaka). This sequence is applicable only in person with normal digestion capacity (agni). In case of abnormal digestion, the sequence can be changed according to the disease condition. The recent researches showed taste like cells in the gut. These cells play an important role in integrating physiological responses during digestion. These taste receptors also influence eating pattern.  The relation between sequence of eating food and its impact on taste receptors in gut need more studies.
Food articles for regular consumption and preservation of health
One should regularly consume shashtika rice (Oryza sativum), shali rice(varieties of Oryza sativum rice), Green gram (mudga, Vigna radiata), rock-salt, Indian-gooseberry (amalaka, Phyllanthus emblica ), barley (yava Hordeum vulgare-), water, milk, ghee, flesh of animals of arid habitat (jangala) and honey. [Cha.Sa.Sutra Sthana 5/12]
Those food items, which maintain health as well as prevent onset of diseases should be included in daily regimen. [Cha.Sa.Sutra Sthana 5/13] One should always take food of all tastes. [Su.Sa. Sutra Sthana 46/492]
Forbidden food articles for habitual consumption
One should not have the habit of taking dried meat, dried vegetables, tuber of lotus (Shaluka, Nymphaea alba Linn.) and stalk of lotus (Bisa, Nymphaea alba Linn.) as these are heavy to digest. One should never eat meat of emaciated animal. [Cha.Sa.Sutra Sthana 5/10] Regular consumption of coagulated milk, cream-cheese, pork, meat of cow and buffalo, fish, curd, black-gram and wild-barley should be avoided. [Cha.Sa.Sutra Sthana 5/11]
Accordingly, one should never eat such heavy to digest articles as preparations of flour, rice, flattened rice etc., on top of a meal. Even while hungry one should take them in right quantity. [Cha.Sa.Sutra Sthana 5/9]
Salt, saturated fats, and excess sugar are disease causing. Excess consumption of animal products leads to premature ageing, increased risk of chronic diseases and higher cause of mortality. Refined carbohydrates including white rice, white bread, sugar, honey, maple syrup, agave nectar lead to overweight, diabetes, dementia, mental illness and cancer. The fast and processed food includes chips, soda, cookies, candy, breakfast cereals, bars, French fries, burgers, pizza, white flour baked goods, and all other high-calorie, low-nutrient foods that people often eat multiple times per day. These food items contribute to obesity, diabetes, heart attacks, strokes, dementia and cancer. This has resulted in decreased longevity. The fast food, processed food, commercial baked goods, and sweets may also be linked to destruction of brain cell and a lowering of intelligence. Candy and sweetened baked goods may even stimulate the brain in an addictive fashion, which can lead to more serious illnesses.  Hence they shall be avoided. One should never eat food which is not sacredly prepared (achoksha), contaminated, with stone particles, grass or hair etc.. The food which causes aversion, kept overnight, foul smelling and stale shall be avoided. The food which does not have its natural taste, hardened due to passage of time, cold, re-heated, with oozing and moisture, burnt shall not be taken. [Su.Sa.Sutra Sthana 46/476-477] Reheated foods cause more oxidative stress through formation of aldehydes and increase the risk of degenerative illness and artherosclerotic disease.  Reheating of cooking oils like corn, soyabean, and sunflower oils produces toxin named 4-hydroxy-trans-2- nonenal (HNE). This is responsible for increased risk of cardiovascular disease, stroke, Parkinson's disease, Alzheimer's disease, Huntington's disease, various liver disorders, and cancer.  Therefore reheating of food shall be avoided. One should not be habituated to consume food having a single taste, foods of inferior quality, unsuitable to human being and sour foods. [Su. Sa. Sutra Sthana 46/491]
The suppression of urge of hunger and its treatment
One shall not suppress the natural urge of hunger for a longer duration. It leads to emaciation, weakness, change in body complexion, generalized body ache, aversion (to food) and dizziness. Such cases are treated by unctuous, hot and light (easily digestible) food is advised. [Cha.Sa.Sutra Sthana 7/20]
These effects are observed after starvation for a longer time due to depletion of glucose, then fatty acid break down and formation of ketone bodies. The treatment is done with sips of water mixed with glucose, fruit juices to avoid refeeding syndrome. 
Personal well being
One should eat after washing hands, face, mouth and feet and dressed appropriately. Reciting mantras, offering oblation to God, departed forefathers, guests and dependents is good practice. Wearing of precious stones while eating has been the practice in the past, is being followed in some societies. [Cha.Sa.Sutra Sthana 8/20] It is important to maintain personal hygiene, prevent negative effect of metaphysical powers while eating.
Effect of sound on health
Reciting mantra or offering prayer before eating is observed in some societies. Mantra is a sacred utterance, a numinous sound, a syllable, word or phonemes, or group of words in Sanskrit believed by practitioners to have religious, magical or spiritual powers. Hymns and sacred chants are observed in all religious scripts.  The term mantra in Sanskrit means "to think". Since ancient times, mantras have been used to calm the mind and produce a sense of peace. Recently, scientists have confirmed this calming effect and have discovered the causal factors within the brain/mind that bring it about. 
Mantra (prolonged repetitive verbal utterance) showed psychological calming effect by reducing the blood oxygenated level dependent signals in brain. 
The structure of Gayatri Mantra is in perfect tune with the science of cosmic sound. Chanting of mantra can enhance spiritual energy, increase self-awareness, cognizance level.  On the other side, ample evidence shows that exposure to environmental noise has adverse effects on the health of the population. A report from the world health organization showed evidence on the relationship between environmental noise and health effects, including cardiovascular disease, cognitive impairment, sleep disturbance, tinnitus, and annoyance. 
Influence of mental status on digestion
One should eat with a stable and pleasant state of mind. The wholesome food, though taken in the right quantity, does not get digested properly, if the mental state of the person is riddled with anxiety, grief, fear, anger, or restlessness and irritability due to lack of sleep.[ Cha.Sa.Vimana Sthana 2/9] One should not take food with greed, ignorance, [Cha.Sa.Sutra Sthana 28/41] passion/desires, greed, infatuation, envy, bashfulness, conceit, excitement and fear in mind. The negative mental factors can harm the digestion process leading to formation of ama (undigested food) and a number of metabolic disorders. [Cha.Sa.Vimana Sthana 2/8]
One should eat with utmost concentration on the food and avoid mental distractions like watching television, reading newspapers, checking emails and working. One should avoid talking or laughing during meals. This can lead to the same defects as by eating too fast discussed later in this article. [Cha.Sa.Vimana Sthana 1/25.9] The mental distractions showed overeating leading to obesity. While paying attention to a meal was linked to eating sufficient meal and lesser chances of gaining weight. Thus, paying attention to meal is directly linked to satiety and weight gain. A concept of mindful eating is originated on these practices. 
- One should eat in pleasant surroundings with soothing fragrance around.
- Facing towards the north direction while eating is said to have beneficial positive effect on health. According to ancient Indian architecture (vastu shastra), the north direction is full of divinity and spiritual energy. However scientific research is needed to study effect of direction while eating.
- The attendants serving food shall be loyal, disciplined, clean and devoted to impart pleasant surroundings. [Cha.Sa.Sutra Sthana8/20]
Appropriate place of eating and accessories
One should not eat at crowded place [Cha.Sa.Sutra Sthana 8/20] to avoid mental distractions and spread of micro-organisms through contact. Physical distancing measures should be followed to avoid microbial infections from person to person. One should eat at a suitable place. It is important to feel comfortable and satisfied while eating. [Cha.Sa.Vimana Sthana1/25.6] Cooking and dining place (mahanasa) shall be clean, spacious and sacred with stay of pure hearted people(apta-avyabhicharinah). [Su.Sa. Sutra Sthana 46/446] Utensils made up of metals shall be used to process and store cooked food. [Su.Sa.Sutra Sthana 46/449-457] The hygiene at the place of eating is of utmost importance to avoid microbial contamination of food and its diseases. The utensils used for cooking, preparing and storing food shall not possess antagonistic properties to that of food. The interaction can cause harmful effects on health.
Duration of taking meals
One should not eat too fast to avoid entry of food particles in nasal passage. By eating with normal speed, the person is able to ascertain the qualities and taste of the food or even detect any defects in the food. [Cha.Sa.Vimana Sthana 1/25.7]
One should not eat too slow. Eating too slow can affect satiety and lead to eating in excess quantity. As the time passes, the cooked food becomes cold and is not digested properly. [Cha.Sa.Vimana Sthana 1/25.8]
A research on eating speed shows that eating quickly (within 9 minutes) leads to poor digestion, increased weight gain, and lower satisfaction. However, slow eating for 29 minutes showed better digestion, better hydration, easier weight loss or maintenance, and greater satisfaction. Mindful eating has suggested ideal eating time as 20 minutes with complete attention on meals.
Eight specific factors before taking food
Eight specific factors shall be considered while consuming food as they are responsible for good and bad effects on the health. [Cha.Sa.Sutra Sthana 28/43]
These eight specific factors are as described below:
1. Nature of food (prakriti)
The natural properties of food like heavy or light to digest etc. shall be considered and appropriately combined as discussed earlier. [Cha.Sa.Vimana Sthana 1/22.1]
The dietary guidelines focus on presence of proportion of carbohydrate, protein, fats, macro nutrients, micro nutrients, phytochemicals, anti-oxidants in the food item.
2. Processing of food (karana)
The term ‘processing’ includes techniques of preparation and cooking fresh food. The food preparation techniques can modify properties of food substances. These properties are imparted by contact of water and fire, by cleansing, churning, place, time, infusing, steeping, etc. and also by the medium used for storage or preparing it (e.g., copper vessel, or earthen pot), etc. [Cha.Sa.Vimana Sthana 1/22.2]
Eating warm and freshly cooked food
One should eat warm and freshly cooked food. It tastes well and the warmth stimulates digestion, reduces gastric emptying time, normalizes functions of vata and reduces kapha dosha which obstructs digestion. [Cha.Sa.Vimana Sthana 1/25.1] Cooking exposes the food to heat and changes physical and chemical properties of food. The digestibility and molecular patten of food is altered after cooking. It also alters the bacterial diversity in gut influencing the gut microbiome after digestion. The techniques of preparation of food can affect feeding time, interest of taking food and digestion processes.  It is observed that cooked and freshly prepared food is more preferred over raw food by humans. Food processed and preserved by modern food technologies like smoking, curing, salting, adding sugar, and/or the addition of chemical preservatives alters natural properties. This food is harmful for health. Research shows that avoidance of processed food can reduce risk of obesity, type 2 diabetes, cancer and cardiovascular diseases. [Dietary guidelines for USA population pg. 25]
Inclusion of unctuous portion
One should eat food with unctuous substance. It tastes well. It stimulates dormant digestive processes, gets digested quickly, helps in normalizing functions of vata dosha, nourishes body, provides firmness to sense organs, increases strength, and enhances complexion. [Cha.Sa.Vimana Sthana 1/25.2]
The unctuous substance (sneha) provides good digestive power, proper evacuation of bowels, optimum quality of body constituents, optimum strength, good complexion, proper functioning of sense organs and longevity. [Su.Sa.Chikitsa Sthana 31/56]. it subsides vata, makes body soft and disintegrates the morbid materials. [Cha.Sa. Siddhi Sthana 01/08]
Unctuous dietary substances like ghee and oil are commonly used for cooking food. These are main sources of fatty acids. Various types of cooking oil contribute as medium of heat transfer, flavour and texture of food. 
Aggregation or combination of two or more food substances can exhibit modified or different properties due to food: food interactions. [Cha.Sa.Vimana Sthana 1/22.3]
Eat suitable combination of food
One should take variety of food items that are not antagonistic to each other. The combinations of antagonistic substances (viruddha ahara) cause various disorders. [Cha.Sa.Vimana Sthana 1/25.5]
There are eighteen varieties of commonly observed antagonistic combinations (viruddha). Antagonistic or incompatible (viruddha) food causes impotency, blindness, erysipelas, ascites, pustules, insanity, fistula-in-ano, fainting, narcosis, tympanitis, spasm in the throat, anaemia, cellular toxins (ama visha), leukoderma, leprosy, digestive disorders, oedema, acid gastritis, fever, rhinitis, genetic disorders and even death. [Cha.Sa.Sutra Sthana 26/102-103] The incompatible food can lead to psychiatric disorders like psychosis (unmada) [Cha.Sa.Chikitsa Sthana 9/4] and epilepsy (apasmara) [Cha.Sa.Chikitsa Sthana 10/4]. The combination of incompatible food substances in dier shall be avoided. Combination of honey and ghee in equal proportions show deleterious effect on health. A study revealed that heated honey (>140°C) mixed with ghee produces hydroxymethyl furaldehyde (HMF) which may produce deleterious effects and act as a poison in due course.  Its formation has been the topic of significant study as HMF was regarded as being potentially carcinogenic to humans.  In another experimental study on Charles foster rats, Combination of honey and ghee in equal proportion showed significant increase in oxidative stress at cellular level. This is due to increased formation of Amadori product, dipeptidyl protease(DPP-4) activity and low incretins glucagon like peptide (GLP-1), gastric inhibitory polypeptide (GIP) activity resulting in high postprandial hyperglycemic response.  Regular consumption of incompatible foods (samyoga viruddha) can induce inflammation at a molecular level. It can disturb the eicosanoid pathway creating more arachidonic acid and increased prostaglandin-2 and thromboxane. This can lead to improper function of digestive system (agni mandya), formation of undigested food and toxins (ama) and a number of metabolic disorders. 
4. Quantity (rashi)
Details about quantity of food are discussed earlier.
5. Geographical origin of food (desha)
The local food grown in that particular geographical region is suitable for people living in that habitat. [Cha. Sa. Vimana Sthana 1/22.5] The geographic region or habitat of that food substance and population shall be considered. Diversity in traditional health foods is observed in various regions based upon the climate, culture, and cropping practices of that particular region. Certain foods become more popular according to the health condition of a population. 
6. Season or time (kala)
The season in which food items show their highest potency, time of their consumption are important to be considered. Consumption of untimely grown and artificially matured food items are hazardous. Untimely consumption is also cause of disease. [Cha.Sa.Vimana Sthana 1/22.6]
Seasonal changes in diet
The physiological changes in human being (microcosm) are predominantly affected by the changes in external environment in universe (macrocosm). e.g, geothermal changes due to the Sun and the Moon, seasonal changes due to rotation of the Earth around the Sun. Similarly, the digestive strength of an individual is also affected by seasonal changes. The properties of food substances also vary according to season. Therefore, one shall follow diet as per seasonal regimen described in chapter on seasonal regimen Tasyashitiya adhyaya. [Cha.Sa.Sutra Sthana 6] The food grown in a particular season shall be consumed in that season only.
Proper time of taking food
One should eat only when the previous meal is digested. If one eats before earlier meal is digested, mixing with undigested food quickly aggravates all dosha. Eating after digestion of previous meals is important to maintain equilibrium of dosha, normal digestion and metabolism and appetite. It helps in cleansing of body channels, pure eructation, normal functioning of heart, normal natural urges to expel body wastes and prevent obstruction to their passage. Thus, it enhances longevity by maintaining quality of dhatu (body components). [Cha.Sa.Vimana Sthana 1/25.4]
There are two phases of digestive cycle: anabolic and catabolic. The first phase of digestion includes eating and digestion. Catabolic phase starts when the digestion is ceased. In the anabolic phase, body stores glycogen, fats and wastes. In catabolic phase, the body effectively detoxifies itself and enhance cellular repair. At this time, the liver and kidney remove harmful metabolic products like aldehydes, advanced glycation end-products (AGEs) and toxic metabolites. One should eat when the true hunger is felt. It is a mild sensation felt in throat and base of neck. It heightens taste sensitivity and ensures pleasurable eating. The true hunger is felt after completing the catabolic phase of digestion. 
A review of researches showed that kalabhojana i.e. eating at scheduled time can produce long term beneficial effect on human health. Timely eating also reduces risk and prevents many metabolic disorders. The researchers also depicted advantages of kalabhojana over time restricted feeding.
7. Rules of taking food (upayoga samstha)
The rules of taking diet show specific post digestive effects. For example, taking food in state of indigestion leads to aggravation of all three dosha. Therefore, the food should be taken only after complete digestion of previous taken food. These rules are elaborated further in the later part of article. [Cha.Sa.Vimana Sthana 1/22.7] This includes all guidelines included in this article.
8. User (upayokta)
Suitability of food (satmya) to the user shall be considered. The adaptation or habituation developed by practice (oka satmya) also depend upon suitability to the user. [Cha.Sa.Vimana Sthana1/22.8] The unsuitable food includes that which is disliked by the consumer and which causes constipation, burning sensation. It can lead to formation of ama (undigested food and toxins). [Cha.Sa.Vimana Sthana 2/8]
Eating with self-awareness
One should eat with self-awareness i.e., knowing one’s own constitution, suitability and tastes. [Cha.Sa.Vimana Sthana 1/25]
Suitability of food to fundamental constitution (prakriti) of a person
|Sr. No.||Fundamental constitution||Properties of suitable food|
|1||Vata dominant constitution||Pacifying Taste: Sweet, Sour and Salty
|2||Pitta dominant constitution||Pacifying Taste: Sweet, Bitter and astringent
|3||Kapha dominant constitution||Pacifying Taste: Pungent, Bitter and astringent
An intuitive eating pattern includes food choices based on hunger, satisfaction and pleasure of eating. 
Cumulative importance of eight factors
The effects of these eight factors are cumulative and inter-dependent. For example, a substance of optimum quantity taken in the right season and in the right place will only produce wholesome effect. Therefore, before prescribing any food regimen, thorough understanding of these eight aspects is important to achieve wholesome effect. [Cha.Sa.Vimana Sthana 1/23] All eight factors are equally important to attain beneficial effect of food. [Cha.Sa.Vimana Sthana 2/4]
Guidelines after meals
Water shall be taken in suitable quantity during meals and after meals. [Su.Sa. Sutra Sthana 46/482]
Drinking suitable quantity of water during meals assures proper passage of food in alimentary canal, mixing in stomach and digestion.
To prevent decaying of teeth and bad smell (halitosis), mouth should be thoroughly cleaned after eating. [Su.Sa.Sutra Sthana 46/483]
Kapha is aggravated after taking food and produces discharge in oral cavity. One shall take mixture of areca nut (puga), cubeb (kankola), camphor (karpura), clove (lavanga) or fruits of pungent, astringent taste with betel leaf as mouth freshener. [Su.Sa.Sutra Sthana 46/484-486]
After taking food, one should sit comfortably like a king (rajavat) till the drowsiness due to food is over. After that one should walk slowly for hundred steps and rest by lying on the left side. One shall observe those measures which soothes, nourish senses and feels good. [Su.Sa. Sutra Sthana 46/487] After meals, sleeping and sitting for longer time, excess liquid diet, exposure to heat, swimming, travelling, riding shall be avoided. [Su.Sa.Sutra Sthana 46/491]
Faulty dietary habits
The improper dietary habits disturb process of digestion and metabolism(agni), lead to formation of ama (undigested food and toxins) and cause severe diseases of various body systems. [Cha.Sa.Chikitsa Sthana 15/42-49]. The following dietary habits can cause severe diseases or death.
- Taking of wholesome and unwholesome food together (samashana) shall be avoided.
- Taking food in excess quantity or less quantity or at improper time (vishamashana) shall be avoided.
- Taking food without complete digestion of previous meals or during indigestion (ajirna) (adhyashana) shall be avoided. [Cha.Sa.Chikitsa Sthana 15/235-237] [Su.Sa. Sutra Sthana 46/508-509] [A.Hr. Sutra Sthana 8/33-34]
Importance of food
Food is most essential for sustenance of life (vrittikara). [Cha.Sa. Sutra Sthana 25/40] The body is constituted and nourished by food. [Cha.Sa. Sutra Sthana 28/41] The origin of life and diseases is food. Wholesome and unwholesome food articles are responsible for happiness and sorrow respectively. Food decides whether the body can or cannot sustain the diseases of body and mind. [Cha.Sa. Sutra Sthana 28/47-48]
The ingested food after proper digestion and metabolism nourishes the tissues, results in plumpness, strength, complexion, health and longevity. The tissues are sustained by getting fed by various nourishing factors (poshaka dhatus). [Cha.Sa. Sutra Sthana 28/3] A detailed list of dietary preparations and therapies having superior qualities (agrya samgraha) that keep a person healthy is given in chapter Yajjah Purushiya Adhyaya. A skillful physician should prescribe the right dietary regimen and therapy after gaining a thorough understanding of the qualities of these articles. Attainment of eternal duties(dharma) and all desires (kama) depends upon this prescription. [Cha.Sa. Sutra Sthana 25/40-44]
Multi-factorial effect of food and diet in health and diseases
An individual consuming wholesome food is not afflicted by disease. However, intake of wholesome food is not the only causative factor for a disease or can prevent diseases. Apart from unwholesome food, there are many other etiological factors that lead to a disease, such as change in season, intellectual errors, unwholesome contacts, excessive, wrong and over-utilization of senses of sound, touch, vision, taste and smell.
These etiological factors can cause diseases in an individual despite wholesome intake of tastes (rasa) and diet. Hence, an individual taking wholesome food has also been observed to have taken ill.
Similarly, consuming unwholesome diet does not immediately produce untoward effects. All unwholesome food articles are not equally harmful, all the dosha are not of equal strength, and all the bodies are not capable of preventing disease.
Unwholesome food can be more harmful depending upon the habitat, season, combination, potency, and intake in excessive quantity. The dosha become acute and extremely difficult to manage when they get associated with multiple factors, treated with wrong therapies, become deep rooted, chronic, get vitiated in one of the ten seats of vitality (prana), and when they afflict vital centers within the body known as 'marma'.
Individuals, who are excessively obese, emaciated, whose muscles, blood, bones are depleted, who are physically very weak, who are habituated to consuming unwholesome food, who take in inadequate quantities of food, and who have very weak mind cannot withstand diseases. Contrary to this, individuals having opposite qualities to the ones mentioned above are capable of resisting diseases. Thus, unwholesome diet, dosha, and body constitution factors produce diseases of mild, severe, acute and chronic nature. [Cha.Sa.Sutra Sthana 28/7]
Cha. = Charak, Su. = Sushruta, Sa.= Samhita, A.Hr. = Ashtanga Hridaya
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