Learn — Macronutrients, energy & dietary guidelines

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Caloric requirements by age

The energy requirement is the amount of dietary energy needed to maintain body size, body composition and a level of physical activity consistent with long-term health, and in a growing child or a pregnant woman it includes the extra energy deposited as new tissue. It matters at the bedside because every therapeutic diet, every infant feeding plan and every antenatal counselling session is written from these figures, and because both under-feeding a sick patient and over-feeding a sedentary one cause measurable harm.

The fuels do not carry equal energy: carbohydrate and protein give about 4 kcal per gram, fat gives 9 kcal per gram and alcohol about 7 kcal per gram, which is why a small change in the fat content of a diet moves the calorie count more than a large change in the rice.
A balanced Indian diet takes roughly 50 to 60 per cent of energy from carbohydrate, 20 to 30 per cent from fat and 10 to 15 per cent from protein, with the protein of a vegetarian diet made complete by combining a cereal with a pulse — rice with dal, or roti with rajma — since the amino acid each lacks is supplied by the other.
Infants need about 100 kcal per kilogram per day in the first year, which is three to four times the adult requirement per kilogram, because the resting metabolic rate is high and growth is fast; the classic paediatric estimate thereafter is about 1000 kcal at one year with roughly 100 kcal added for each additional year of age until adolescence.
The same stepwise pattern is used for weight-based estimation: 100 kcal per kilogram for the first 10 kg of body weight, 50 kcal per kilogram for the next 10 kg and 20 kcal per kilogram for every kilogram beyond 20 — the calculation from which the standard maintenance fluid rule is derived.
Adult requirement is set by body weight and by activity, and the current ICMR-NIN 2020 tables give a sedentary reference man of 65 kg about 2110 kcal and a sedentary reference woman of 55 kg about 1660 kcal per day, rising through moderate (2710 and 2130 kcal) to heavy activity (3470 and 2720 kcal); many Indian nursing texts still print the 2010 figures of 2320 and 1900 kcal, so quote the edition with the number.
Pregnancy adds about 350 kcal a day over the woman's pre-pregnancy requirement, with extra protein (9.5 g a day in the second trimester and 22 g in the third in the ICMR-NIN 2020 tables; older texts give 23 g), and lactation adds about 600 kcal a day in the first six months and rather less in the second six months — advice that is given alongside iron-folic acid and calcium supplementation.
Requirement rises with illness: fever, sepsis, major surgery, burns and trauma all increase energy and protein needs, while immobility, sedation and mechanical ventilation reduce them, so a critically ill patient's feed is prescribed on a calculated requirement and reviewed, not left at a standard rate.
Whether intake matches requirement is judged not by the calculation but by the patient: serial weight, the body mass index against the Asian Indian cut-offs of 23 for overweight and 25 for obesity, mid-upper arm circumference in a child, and the growth chart, which detects faltering long before a calorie count does.

Protein synthesis — translation

Translation is the synthesis of a polypeptide on the ribosome from the codons of a messenger RNA, using transfer RNAs as adaptors that match each anticodon to its amino acid. It is the step at which the genetic message finally becomes a working protein, and it matters at the bedside for a very practical reason: the differences between the bacterial 70S ribosome and the human 80S ribosome are what make an entire class of antibiotics possible, while the fact that human mitochondria also carry 70S ribosomes is what makes those same antibiotics toxic.

The genetic code is read in triplets; it is degenerate because most amino acids have more than one codon, non-overlapping, without punctuation and almost universal. AUG is the initiation codon and codes for methionine — formylmethionine in bacteria — and UAA, UAG and UGA are the three stop codons that code for no amino acid.
Initiation: the small ribosomal subunit, initiation factors and GTP assemble on the messenger RNA at the start codon, guided in bacteria by the Shine-Dalgarno sequence and in eukaryotes by the 5-prime cap with scanning, after which the large subunit joins to form the complete ribosome with the initiator transfer RNA in the P site.
Elongation: an aminoacyl transfer RNA enters the A site, peptidyl transferase — which is a ribozyme activity of the large subunit's ribosomal RNA and not a protein — forms the peptide bond, and translocation moves the ribosome one codon along, consuming GTP and elongation factors; the chain grows from the amino to the carboxy terminus while the messenger RNA is read in the 5-prime to 3-prime direction, and several ribosomes read the same message at once as a polysome.
Termination: a release factor recognises the stop codon in the A site, the completed polypeptide is hydrolysed from the transfer RNA and the subunits dissociate.
The protein is not finished when translation ends: post-translational modification includes cleavage of the signal peptide, folding assisted by chaperones, glycosylation in the endoplasmic reticulum and Golgi, hydroxylation of proline and lysine in collagen which requires vitamin C, gamma-carboxylation of clotting factors which requires vitamin K, phosphorylation, and proteolytic activation such as the conversion of proinsulin into insulin and C-peptide.
Antibiotics are grouped by which subunit they attack: aminoglycosides cause misreading and tetracyclines block the A site, both on the 30S subunit, while macrolides, clindamycin, chloramphenicol and linezolid act on the 50S subunit; mupirocin blocks isoleucyl transfer RNA synthetase, and the toxins of diphtheria and Pseudomonas inactivate eukaryotic elongation factor 2.
Because human mitochondrial ribosomes are 70S like bacterial ones, these drugs are not perfectly selective: chloramphenicol causes dose-related bone marrow suppression, idiosyncratic aplastic anaemia and, in the neonate whose liver cannot conjugate it, the grey baby syndrome, while prolonged linezolid causes cytopenias, lactic acidosis and optic and peripheral neuropathy.
Mutations show their effect here: a silent mutation changes the codon but not the amino acid, a missense mutation substitutes one amino acid for another — glutamate for valine at the sixth residue of the beta globin chain gives sickle cell disease — a nonsense mutation creates a premature stop codon and a truncated protein, and an insertion or deletion that is not a multiple of three shifts the reading frame and destroys everything downstream.

Keratin — structural protein

Keratin is the family of tough, insoluble fibrous proteins that form the intermediate filaments of epithelial cells and make up the bulk of hair, nails and the horny outer layer of the skin. Its strength comes from its unusually high cystine content, because disulphide cross-links between cysteine residues lock the coiled chains together, and this matters at the bedside because keratin is the barrier that keeps water in and organisms out, so wherever it thickens, cracks or is lost, infection and ulceration follow.

Alpha-keratin is the mammalian form, built from alpha-helical chains wound into coiled coils, and is found in hair, wool, nails, horn and skin, while beta-keratin is arranged in beta-pleated sheets and is found in reptile scales, feathers and beaks; alpha-keratin can be stretched because its hydrogen bonds yield, whereas beta-keratin cannot.
The disulphide bridges between cysteine residues are what make hard keratin rigid and insoluble, and they can be broken and re-formed chemically — which is exactly what the reducing and oxidising steps of hair perming and straightening do.
Keratins are also the intermediate filaments of epithelium, and because they are tissue-specific, cytokeratin immunostaining identifies a tumour as a carcinoma of epithelial origin, in contrast with vimentin staining in a sarcoma of mesenchymal origin.
Skin keratinocytes are formed in the basal layer, migrate outward filling with keratin, die and are shed as the stratum corneum; the turnover takes about four weeks in normal skin but only a few days in psoriasis, which is why the plaques carry a thick silvery scale.
Growth rates are the practical numbers: hair grows roughly a centimetre a month, a fingernail about 3 mm a month and a toenail considerably slower, so a fingernail takes about six months and a toenail a year or more to be completely replaced — the reason antifungal treatment for a nail infection must continue for months and cannot be judged after a fortnight.
Hair grows in cycles of anagen, catagen and telogen, and a severe stress such as a high fever, major surgery, childbirth or a serious illness pushes many follicles into the resting phase at once, producing the alarming but self-limiting shedding of telogen effluvium about two to three months later.
Dermatophyte fungi are keratinophilic and digest keratin, which is why tinea affects skin, hair and nails and why a potassium hydroxide preparation, which dissolves keratin, is used to reveal the hyphae in a skin scraping.
Disorders of keratin are examined through their names: mutations in the basal keratinocyte keratin genes cause epidermolysis bullosa simplex, in which the skin blisters with minor friction; vitamin A deficiency causes follicular hyperkeratosis and keratomalacia of the cornea; and pressure or friction produces callus and corn, which are simply local overgrowth of the horny layer.

ICMR-NIN 2020 RDA — EAR, RDA, TUL and the reference adult

The Recommended Dietary Allowances for Indians are the daily intakes of energy, protein, fat, vitamins and minerals that the ICMR-National Institute of Nutrition expert group judges sufficient for practically all healthy people of a given age, sex, body size and activity, published in successive editions of which the 2020 report is current. The 2020 revision is the one the exam asks because it changed the reference adult, gave India its first Estimated Average Requirements alongside the allowances, and set the numbers — 2110 kcal, 0.83 g of protein per kilogram, 54 and 46 g — that every diet plan, feeding norm and antenatal counselling session in the country is now built on.

The vocabulary: the Estimated Average Requirement (EAR) is the intake that meets the needs of half the healthy people in a group and is the figure for judging the adequacy of a population's intake; the Recommended Dietary Allowance (RDA) is the EAR plus two standard deviations, meeting the needs of 97.5 per cent, and is the figure for planning an individual's diet; the Tolerable Upper Limit (TUL) is the highest routine intake without risk; an Adequate Intake is used where no EAR can be set; energy has only a requirement, never an allowance, because feeding everyone at the upper bound would make half of them fat.
The reference Indian adult of 2020 is a man of 65 kg and a woman of 55 kg, aged 19 to 39, healthy, of a stated height and body mass index — the reference man was 60 kg in the 2010 tables — and requirements for everyone else are scaled from these two; physical activity is graded sedentary, moderate and heavy by the physical activity level multiplied on the basal metabolic rate.
Energy: a sedentary man needs about 2110 kcal a day, a moderately active man 2710 and a heavy worker 3470; a sedentary woman 1660, moderately active 2130 and heavy 2720; pregnancy adds 350 kcal a day in the second and third trimesters, lactation adds 600 kcal in the first six months and 520 in the next six.
Protein: 0.83 g per kilogram of body weight a day of a good-quality mixed diet, which is 54 g for the reference man and 46 g for the reference woman, with additions of about 9.5 g a day in the second trimester and 22 g in the third trimester of pregnancy and 19 g and 13 g in the two halves of lactation; the 2010 figure of 1 g/kg is still quoted in older texts.
Fat and the rest: visible fat of about 25 g a day for a sedentary adult rising to 30 to 40 g with activity, with total fat at 20 to 30 per cent of energy; dietary fibre of about 30 g a day (40 g per 2000 kcal); salt under 5 g; and the micronutrients that come up most — iron 19 mg (men) and 29 mg (women), calcium 1000 mg, vitamin C 80 and 65 mg, and folate 300 and 220 micrograms, with 570 in pregnancy.
The allowances are for healthy people and are not a prescription for the sick: illness, fever, sepsis, burns and surgery raise energy and protein needs, kidney and liver disease change the protein figure in opposite directions, and the dietitian works from the patient's condition and weight, using the RDA only as the healthy baseline.
The tables drive the programmes: the ICDS supplementary nutrition norms, the PM POSHAN meal norms, the antenatal supplements and the consumption unit of a diet survey are all derived by taking a fraction of the reference man's requirement, and the sedentary reference man is by definition one consumption unit.

Carbohydrates and fibre — types, functions and the sugar limit

Carbohydrates are the sugars, starches and fibres of plant foods that supply 4 kcal per gram and most of the energy of an Indian diet, from the simple monosaccharides and disaccharides the gut absorbs at once to the starches it digests slowly and the dietary fibre it cannot digest at all. Their nutrition is a question of kind rather than amount: whole grains, millets and pulses with their fibre are the base of a healthy plate, while refined cereals and free sugars are the base of obesity, diabetes and dental caries, which is why the guidelines now set a ceiling on sugar and a floor on fibre.

Classification: monosaccharides glucose, fructose and galactose; disaccharides sucrose (glucose plus fructose), lactose (glucose plus galactose) and maltose (glucose plus glucose); oligosaccharides such as the raffinose of pulses, which the gut cannot digest and the colon ferments into gas; and polysaccharides — starch (amylose and amylopectin), glycogen, and the non-starch polysaccharides that make up dietary fibre.
Functions: the main fuel of brain and red cells, which need about 100 to 130 g of glucose a day; protein sparing, because with enough carbohydrate the body does not burn amino acids for energy; anti-ketogenic, because fat is fully oxidised only when carbohydrate is available; and structural, in glycoproteins and glycolipids; the liver stores about 100 g and muscle 300 to 400 g as glycogen, enough for less than a day of fasting.
Quantity: carbohydrate supplies 55 to 60 per cent of energy in a balanced Indian diet, and the 2020 allowances put the acceptable range at 45 to 65 per cent; the concern is not the total but the share that is refined — polished rice, maida and sugar — against the share from whole grains, millets, pulses, vegetables and fruit.
Free sugars — sugar, jaggery, honey and the sugar of juices and sweetened drinks — should stay under 10 per cent of energy and ideally under 5 per cent, which the 2024 Indian guidelines adopt as the limit, about 20 to 25 g or five teaspoons a day; a single 300 mL bottle of a sweetened drink carries more than that and is the single easiest thing to remove from a child's diet.
The glycaemic index ranks a food by the rise in blood glucose over two hours against glucose itself: low at 55 or below (pulses, whole grains, oats, most fruit, curd), medium at 56 to 69, high at 70 and above (white rice, maida products, potato, sugar); the glycaemic load multiplies the index by the portion, and cooking, ripeness, fibre, fat and protein in the same meal all lower the response.
Dietary fibre: soluble fibre (oats, barley, pulses, fruit pectin, psyllium) forms a gel that slows glucose absorption and binds bile acids to lower cholesterol; insoluble fibre (wheat bran, whole grains, vegetables) adds bulk and speeds transit; the allowance is about 30 g a day, or 40 g per 2000 kcal, reached only with whole grains, whole pulses, vegetables and fruit with their skins, and increased gradually with fluids because a sudden jump gives bloating and, in excess, binds iron, calcium and zinc through its phytate.
Lactose intolerance is the commonest carbohydrate malabsorption in Indian adults — bloating, cramps and diarrhoea after milk because intestinal lactase falls after childhood — and it is managed by curd, buttermilk and hard cheese, small amounts of milk with meals, or lactase; it is not a milk allergy and it is not a reason to give up calcium.

Proteins — quality, biological value and requirements

Dietary protein supplies the nitrogen and the nine indispensable amino acids the body cannot make, for the growth, repair and turnover of every tissue, the enzymes, hormones and antibodies, and, at 4 kcal per gram, some energy; its worth to the body depends on quality as much as quantity, measured by how completely the absorbed amino acids can be used. In an Indian diet built on cereals and pulses the quality question is the practical one: no single plant food is complete, but the right two eaten together are.

Quality measures, each asked by name: biological value is the percentage of absorbed nitrogen retained by the body — egg 100, milk about 90, fish and meat 75 to 80, soya about 75, cereals and pulses 60 to 70; net protein utilisation multiplies biological value by digestibility — egg about 96, milk 81, meat 75 to 80, cereals 50 to 60; the protein efficiency ratio is weight gained per gram of protein eaten in a growing animal; and the amino acid score compares the limiting amino acid with the reference pattern, corrected for digestibility as PDCAAS and, since 2013, DIAAS.
Egg protein is the reference protein because almost all of it is retained, so egg and milk are the complete proteins of an Indian diet, and soya is the one plant protein that comes close; the limiting amino acid of cereals (rice, wheat, maize) is lysine, and of pulses methionine and cysteine, so each supplies what the other lacks.
Mutual supplementation is the single most useful counselling fact: dal with rice, roti with dal, idli with sambar, khichdi, and a cereal-to-pulse ratio of about 5:1 by weight give a protein of near-animal quality at a fraction of the cost, and the two need to be eaten at the same meal or close to it for the effect.
Requirement: 0.83 g per kilogram a day — 54 g for the reference man and 46 g for the reference woman — with additions of about 9.5 g and 22 g in the second and third trimesters and 19 g and 13 g in the two halves of lactation; a growing child, a wound, a burn or sepsis raise the figure to 1.2 to 2 g/kg, chronic kidney disease before dialysis lowers it, and protein supplements above about 1.6 g/kg add nothing to the muscle of a healthy adult.
Sources by content: soya about 40 g per 100 g, pulses and legumes 20 to 25 g, nuts 15 to 25 g, meat, fish and chicken 18 to 25 g, paneer about 18 g, egg 13 g (one egg gives roughly 6 g), cereals 7 to 12 g, and milk 3.2 g per 100 mL; a vegetarian reaches the allowance through pulses, milk, curd, paneer, soya and nuts, not through cereals alone.
Nitrogen balance is the clinical measure: 6.25 g of protein contains 1 g of nitrogen, intake against loss in urine, stool and skin; growth, pregnancy and convalescence are positive, starvation, fever, injury, immobility and steroids are negative, and serum albumin under 3.5 g/dL, muscle wasting and poor wound healing are the ward signs of a negative balance.
Deficiency at its extreme is protein-energy malnutrition — kwashiorkor when protein fails while energy is kept up, marasmus when both fail — on the paediatric notes; excess protein in a healthy adult is harmless within reason, but it loads the kidney in renal disease, raises urinary calcium loss, and displaces the cereals, fruit and vegetables the rest of the diet needs.

Fats and oils — saturated, unsaturated and trans fats, visible fat allowance

Dietary fat is the most concentrated fuel at 9 kcal per gram, the carrier of the fat-soluble vitamins and the essential fatty acids, and the ingredient that gives Indian food its taste and satiety — eaten as the visible fat of cooking oil, ghee, butter and vanaspati and the invisible fat within cereals, pulses, nuts, milk, eggs and meat. Its health effect depends on kind: saturated and trans fats raise the risk of heart disease, unsaturated fats lower it, and the amount that is safe is set by activity and by the share of energy the rest of the diet leaves for it.

Kinds by structure: saturated fatty acids (ghee, butter, coconut and palm oil, red meat, full-cream milk) have no double bonds and are solid at room temperature; monounsaturated fatty acids (mustard, groundnut, rice bran, olive oil, most nuts) have one; polyunsaturated fatty acids have several — the omega-6 linoleic acid of sunflower, safflower, soybean and corn oil and the omega-3 alpha-linolenic acid of flaxseed, mustard oil, walnuts and fish, both of them essential because the body cannot make them.
Trans fatty acids are made when liquid oils are partially hydrogenated into vanaspati and bakery shortening, and when oils are heated repeatedly; they raise LDL and lower HDL cholesterol and are the worst fat for the heart, so WHO asks for under 1 per cent of energy and FSSAI has limited industrial trans fat in oils and fats to not more than 2 per cent by weight since January 2022.
Amounts: total fat at 20 to 30 per cent of energy in adults and more in young children; visible fat of about 25 g a day for a sedentary adult, 30 g with moderate work and 40 g with heavy work — five to eight teaspoons, since a teaspoon of oil is about 5 g — with saturated fat under 10 per cent of energy and dietary cholesterol, found only in animal foods, under about 300 mg a day.
Cholesterol comes from egg yolk, organ meats, shellfish, ghee, butter and meat and from nothing that grows on a plant, so a cholesterol-free label on a vegetable oil says nothing about the oil; what matters on the label is the saturated and trans content, and an oil that is 'free of cholesterol' but hydrogenated is worse than one that is not.
Oil practice that a nurse teaches: rotate or blend oils so that saturated, monounsaturated and polyunsaturated fats are all represented and the omega-6 to omega-3 ratio stays within about 5 to 10 to 1 (sunflower alone gives 50 to 1); do not reuse frying oil more than two or three times and never top up an old pan, because repeated heating makes trans fats and toxic polar compounds; and remember that fried food absorbs 5 to 10 per cent of its weight as oil.
The functions worth naming: energy storage and insulation, absorption of vitamins A, D, E and K, the essential fatty acids for membranes, retina, brain and prostaglandins, satiety and the palatability that makes a toddler's meal energy-dense — the low-fat adult diet is wrong for a child under two, who needs fat for 30 to 45 per cent of energy.
Therapeutic use: a low-fat diet of under 20 per cent of energy, with medium-chain triglycerides that bypass the lymphatics, is used in steatorrhoea, gallbladder disease, pancreatitis and chylothorax; the cardiac fat rules are on the cardiac diet note, and rancidity — the oxidation of unsaturated oils exposed to air, light and heat — is prevented by cool dark storage and the vitamin E the oil itself carries.

Dietary Guidelines for Indians (2024) and My Plate for the Day

The Dietary Guidelines for Indians, revised by the ICMR-National Institute of Nutrition in 2024 after the 2011 edition, are seventeen plain-language rules for eating well across the life cycle, backed by the 2020 requirement tables and summarised in one picture, My Plate for the Day, which shows what share of the day's food should come from each group. They are the document the exam now quotes for the sugar and salt limits, the warning against ultra-processed foods and protein powders, and the millet-and-vegetable plate that has replaced the food pyramid in Indian teaching.

My Plate for the Day for a sedentary adult on about 2000 kcal: vegetables, greens, roots and fruit fill half the plate by weight — about 400 g of vegetables including 100 g of green leaves and 100 g of fruit; cereals and millets supply about 45 per cent of energy (roughly 250 g); pulses, eggs and flesh foods about 14 to 15 per cent (about 85 g of pulses or their equivalent); milk or curd about 300 mL; nuts and seeds about 30 to 35 g; and cooking oil about 27 g, so that fat stays within 20 to 30 per cent of energy.
The limits: added sugar not more than 5 per cent of total energy, about 20 to 25 g a day; salt under 5 g a day, counting the salt in pickles, papad, namkeen and processed foods; total fat 20 to 30 per cent of energy with saturated fat under 10 per cent and trans fat avoided; and ultra-processed foods — packaged snacks, sweetened drinks, instant foods high in fat, sugar and salt — kept off the daily plate.
The guidelines by life stage: exclusive breastfeeding for six months and complementary foods from six months with continued breastfeeding to two years; extra food, not just extra iron, in pregnancy and lactation; a diverse diet with milk, eggs and pulses for children and adolescents and no sugary drinks; protein, calcium and fibre with enough fluid for the elderly; and physical activity of at least 30 to 60 minutes a day for adults and an hour of play for children.
Two warnings that were new in 2024: protein supplements and powders are unnecessary for a healthy person and may carry added sugar and unregulated additives, and front-of-pack and back-of-pack labels should be read for energy, sugar, salt and fat per serving before a packaged food is bought — the guideline is that the label, not the advertisement, tells the truth.
Millets — jowar, bajra, ragi and the small millets — are placed alongside rice and wheat as everyday cereals for their fibre, minerals and lower glycaemic response, and the traditional Indian meal of a cereal, a pulse, a vegetable, a green leaf, curd and a little oil is presented as the model rather than an imported pattern.
The guidelines' definition of a balanced diet is the one taught for the exam — one that provides all the nutrients in the required amounts and proper proportions to meet the needs of the individual, with a small reserve to withstand short periods of leanness — and they set the food-group basis for it: cereals and millets, pulses and legumes, milk and meat products, fruits and vegetables, and fats and sugars.
Water and drinks: enough safe water through the day (about eight glasses for an adult), tea and coffee an hour away from meals because their tannins block iron, and no alcohol as a dietary component; the guidelines also carry a food-safety section on storage, cooking and hygiene, and a page on healthy cooking methods that keeps steaming and pressure-cooking ahead of frying.

Food groups, food pyramid and exchange lists for meal planning

Food groups sort the thousands of foods into a handful of families that contribute the same nutrients, so that a diet can be planned and checked by asking whether every group is represented rather than by adding up milligrams; the food pyramid and, since 2024, My Plate for the Day are the pictures that show how much of each group to eat. The exchange lists go one step further for the therapeutic diet: within a group, foods are listed in portions that carry the same energy and macronutrients, so a diabetic or a renal patient can swap one for another and keep the day's plan unchanged.

The ICMR five food groups: cereals, grains and their products (energy, some protein, B vitamins, fibre); pulses and legumes (protein, fibre, iron); milk and meat products — milk, curd, paneer, egg, fish, meat (protein, calcium, vitamin B12); fruits and vegetables, subdivided into green leafy vegetables, other vegetables, roots and tubers, and fruits (vitamins, minerals, fibre); and fats and sugars (energy alone).
The nutritional or functional classification is asked as often: energy-giving foods (cereals, roots and tubers, fats, sugars), body-building foods (pulses, milk, egg, fish, meat) and protective foods (fruits, vegetables, milk) — the three-food-group system of the health worker's teaching, and the reason every meal is planned to contain one of each.
The food pyramid put cereals and millets at the wide base, vegetables and fruit above them, pulses, milk and animal foods above those, and fats and sugars at the narrow tip to be used sparingly; My Plate for the Day (2024) now replaces it in Indian teaching with half the plate as vegetables and fruit, and the exam may use either picture.
A balanced diet, in the definition the exam wants, contains a variety of foods in such quantities and proportions that the need for energy, amino acids, vitamins, minerals, fats, carbohydrate and other nutrients is adequately met for maintaining health, vitality and general well-being, and also makes a small provision for extra nutrients to withstand short periods of leanness.
Exchange lists: one cereal exchange is 30 g of raw cereal — one medium chapati, about a third of a cup of cooked rice, one slice of bread or one idli — giving roughly 100 kcal, 20 g of carbohydrate and 3 g of protein; one pulse exchange is 30 g of raw dal (about 100 kcal, 7 g of protein); one milk exchange is 100 mL of milk; one fruit exchange is one small fruit or half a banana (about 40 to 60 kcal); one fat exchange is 5 g or a teaspoon of oil or ghee (45 kcal); one sugar exchange is 5 g (20 kcal); and an egg or 30 g of meat or fish is one protein exchange of about 70 to 80 kcal.
Meal planning is done in steps: fix the energy and protein for the person's age, sex, activity and condition from the 2020 tables; choose the exchanges from every group to meet them; distribute them over three meals and two snacks; check the cereal-to-pulse ratio of about 5:1, a green leafy vegetable and a fruit every day, and the fat and sugar caps; and then fit the plan to the family's food habits, religion, season, cost and cooking arrangements, because a diet no one cooks is not a diet.
Household measures make the plan usable: a katori of about 150 mL, a standard cup of 200 to 250 mL, a tablespoon of 15 mL and a teaspoon of 5 mL, with a medium chapati of about 30 g of flour — and the same measures are the ones a diet survey uses to reconstruct what was eaten.

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