Dietary Requirements & Balanced Diet

Nutrition is among the most reliably scored chapters in Community Medicine, and within it the ICMR Recommended Dietary Allowances (RDA) and the concept of a balanced diet are pure recall marks. This note distils the caloric density of macronutrients, the reference Indian adult, and life-stage RDAs for energy, protein, iron, calcium, and key vitamins into exam-ready tables.

Core Definitions & Concepts

A handful of overlapping terms are repeatedly confused in MCQs, so fix them precisely:

• Recommended Dietary Allowance (RDA): average daily dietary intake sufficient to meet the nutrient requirement of 97–98% (nearly all) of healthy individuals in a group. It equals the Estimated Average Requirement (EAR) + 2 SD. RDA is a recommendation for individuals, not a population average.
• Estimated Average Requirement (EAR): intake meeting the needs of 50% of the group; used for planning population diets.
• Estimated Energy Requirement (EER): for energy, ICMR/WHO does not add 2 SD (adding a safety margin would promote overweight); the recommendation is set at the mean requirement. This is a classic trap — energy = EAR-equivalent, all other nutrients = EAR + 2 SD.
• Tolerable Upper Limit (UL): highest chronic intake unlikely to pose risk of toxicity.
• Reference body weight (ICMR 2020): man 65 kg, woman 55 kg (older texts/Park editions use 60 kg man, 55 kg / 50 kg woman — answer per the source the paper quotes; the long-standing "reference Indian adult man = 60 kg sedentary" still appears).

High-yield: RDA = EAR + 2 SD for all nutrients except energy. For energy, RDA is set at the mean requirement (no 2 SD added) to avoid promoting obesity.

A balanced diet is one that contains different types of foods in such quantities and proportions that the need for energy, amino acids, vitamins, minerals, fat, carbohydrate, and other nutrients is adequately met, plus a small provision for extra nutrients to withstand short durations of leanness.

Caloric Density of Macronutrients

This is the single most repeated factual recall in the chapter.

Nutrient	Energy yield (kcal/g)	Energy yield (kJ/g)
Carbohydrate	4	17
Protein	4	17
Fat	9	37
Alcohol	7	29
Dietary fibre	~2 (negligible)	—

High-yield: Fat yields 9 kcal/g — more than twice carbohydrate/protein. Alcohol gives 7 kcal/g ("empty calories"). 1 kcal = 4.184 kJ.

Proportionate contribution to total energy (balanced diet goals)

Macronutrient	% of total daily energy
Carbohydrate	50–70% (ICMR: ~55–60%; visible/free sugars < 10%)
Protein	10–15%
Fat	20–30% (visible fat ~20–30 g/day; saturated < 10%, trans minimal)

Energy from protein flow: Daily energy 2000 kcal → 12% from protein → 240 kcal ÷ 4 = 60 g protein. Practise this conversion both directions.

The Reference Indian Adult & Activity Levels

Energy requirement = BMR × Physical Activity Level (PAL). ICMR classifies adult activity as sedentary, moderate, and heavy work, each with a PAL multiplier.

Activity (adult man, ~60–65 kg)	PAL	Energy (kcal/day, classic Park figures)
Sedentary work	1.53	~2320–2425 (round to ~2400)
Moderate work	1.8	~2730–2875
Heavy work	2.3	~3490–3800

Activity (adult woman, ~55 kg)	PAL	Energy (kcal/day)
Sedentary	1.53	~1900–2060
Moderate	1.8	~2230–2400
Heavy	2.3	~2850–2925

High-yield: The classic NEET answer for a reference Indian adult man, sedentary is ~2400–2425 kcal/day (older texts say 2320). For a sedentary woman it is ~1875–1900 kcal/day. Know the sedentary values cold.

Flow for energy needs: Reference weight → BMR (≈ weight-based) → × PAL (activity) → total energy requirement → add increments for pregnancy/lactation.

Protein Requirements (RDA)

ICMR safe protein intake for an Indian adult is classically ~1.0 g/kg/day (revised ICMR-2020 figure ~0.83–1.0 g/kg of reference body weight using a quality-adjusted approach). The reference adult man therefore needs roughly 60 g/day.

Group	Protein RDA (approx.)
Adult man (sedentary)	~0.8–1.0 g/kg → ~54–60 g/day
Adult woman	~46–55 g/day
Pregnancy	+ ~7.5–9.5 g/day (≈ +23 g in late pregnancy by ICMR-2020)
Lactation (0–6 mo)	+ ~17–19 g/day
Lactation (6–12 mo)	+ ~13 g/day
Infant 0–6 mo	~1.16 g/kg/day (from breast milk)
Child 1–3 yr	~12.5 g/day

Protein quality terms (frequently tested):

• Biological Value (BV): proportion of absorbed N retained. Egg ≈ 100 (reference), milk ~85, meat/fish ~75, rice ~70, wheat ~60, pulses ~50–60.
• Net Protein Utilisation (NPU) = BV × digestibility.
• Protein Energy Ratio / Mutual supplementation: cereals (limiting in lysine) + pulses (limiting in methionine) together give a complete amino-acid profile — basis of the Indian cereal-pulse diet.

High-yield: Egg has the highest biological value (~100) and is the reference protein. Cereal + pulse = complementary/supplementary proteins correcting each other's limiting amino acid (lysine ↔ methionine).

Iron & Calcium RDA

Group	Iron (mg/day)	Calcium (mg/day)
Adult man	~17–19	800–1000
Adult woman (reproductive)	~21–29 (menstrual loss)	800–1000
Pregnancy	~27–35 (national programme: 60 mg elemental Fe + 500 µg folic acid daily for ≥180 days)	1000–1200
Lactation	~21–25	1000–1200
Infant 6–12 mo	~5–6	300–500
Child / adolescent	rises with growth & menarche	600–800

High-yield: Anaemia Mukt Bharat / national IFA prophylaxis in pregnancy = 100 mg elemental iron + 500 µg folic acid daily for ≥180 days antenatally and continued 180 days postpartum. Adolescent WIFS = weekly 100 mg iron + 500 µg folic acid.

Iron absorption is enhanced by vitamin C, animal (haem) iron and inhibited by phytates, tannins (tea), phosphates, calcium. Indian diets are iron-rich but absorption is low (~3–5%), explaining endemic anaemia despite intake.

Key Vitamin RDAs

Vitamin	Adult RDA	Classic deficiency
Vitamin A	600 µg retinol equiv./day (children 400 µg)	Xerophthalmia, night blindness
Vitamin D	600 IU (15 µg)/day; 800 IU > 65 yr	Rickets / osteomalacia
Thiamine (B1)	0.5 mg/1000 kcal (~1.2–1.4 mg)	Beriberi, Wernicke
Riboflavin (B2)	~1.2–1.4 mg	Angular stomatitis, cheilosis
Niacin (B3)	6.6 mg/1000 kcal	Pellagra (3 D's)
Folate	300 µg (adult); 500–570 µg pregnancy	Megaloblastic anaemia, NTD
Vitamin B12	~2.2 µg	Megaloblastic anaemia, SACD
Vitamin C	40 mg/day (ICMR)	Scurvy

High-yield: Vitamin A national prophylaxis = 1 lakh (100,000) IU at 9 months, then 2 lakh (200,000) IU every 6 months up to 5 years (total 9 doses). Vitamin A RDA for an adult = 600 µg retinol equivalents.

Vitamin A unit conversion (asked): 1 µg retinol = 1 retinol equivalent (RE) = 3.33 IU; 1 µg β-carotene ≈ 1/12 µg retinol (dietary, RAE convention). 6 µg β-carotene = 1 µg retinol by older (RE) convention.

Extra Requirements in Special Physiological States

State	Extra energy	Extra protein	Notes
Pregnancy (2nd/3rd trim)	+350 kcal/day	+9.5 to +23 g	+ iron, folate, calcium, iodine
Lactation (0–6 mo)	+600 kcal/day	+17–19 g	Highest energy demand
Lactation (6–12 mo)	+520 kcal/day	+13 g

High-yield: Memorise Pregnancy +350 kcal, Lactation (0–6 mo) +600 kcal. These exact increments are textbook MCQ favourites. Lactation, not pregnancy, has the higher energy increment.

Mnemonic — "350 for the bump, 600 for the pump" (pregnancy 350, lactation 600).

Components of a Balanced Diet (Food Groups)

ICMR groups foods into five basic groups; the balanced-diet "plate" combines them:

1. Cereals, grains & products — main energy source (~55–60% energy).
2. Pulses & legumes — protein, complement cereals.
3. Milk & animal foods — high-BV protein, calcium, B12.
4. Fruits & vegetables — vitamins, minerals, fibre, antioxidants.
5. Fats, oils & sugars — concentrated energy, EFAs (use sparingly).

Balanced-diet construction flow: Estimate energy need → fix carbohydrate 55–60% → protein 10–15% (≥½ from good-quality sources) → fat 20–30% (visible fat ~20–30 g) → fill micronutrients via fruits/vegetables/milk → ensure 30–40 g fibre.

A useful balanced-diet model is the "My Plate for the Day" (ICMR-NIN 2020): roughly half the plate fruits + vegetables, the rest split between cereals/millets and protein foods, with limited oil/sugar. ICMR-NIN advocates at least 50% of cereals replaced by whole grains and millets, ≥ 3 servings of vegetables and 2 of fruit daily, and protein from a combination of pulses, milk, egg, fish, or meat to ensure adequate essential amino acids.

Essential vs non-essential nutrients

Nine amino acids are essential (cannot be synthesised) — PVT TIM HaLL: Phenylalanine, Valine, Threonine, Tryptophan, Isoleucine, Methionine, Histidine, Leucine, Lysine. Essential fatty acids are linoleic acid (n-6) and alpha-linolenic acid (n-3), deficiency of which causes scaly dermatitis. These cannot be omitted from any "balanced" diet, which is why fat is never reduced to zero.

Reference Values Worth Memorising

Quantity	Value
Visible fat intake	20–30 g/day (sedentary), up to 40–50 g (heavy work)
Dietary fibre	30–40 g/day (≈ 40 g/2000 kcal)
Free/added sugar	< 10% of energy (WHO: ideally < 5%)
Salt	< 5 g/day (WHO)
Cereal:pulse ratio (Indian diet)	~ 7:1 to 8:1 (ideal closer to 4:1)
Saturated fat	< 10% energy; PUFA:SFA balance, n-6:n-3 ≈ 5–10:1

Diagnosis & Assessment of Nutritional Adequacy

While "investigation of choice" is clinical here, the methods of dietary/nutritional assessment are examinable:

• Diet survey methods: 24-hour recall, food frequency questionnaire, weighment method (most accurate = weighment), expenditure/inventory.
• Anthropometry: weight-for-age, height-for-age, weight-for-height (BMI in adults; Waterlow/WHO classification, MUAC in children).
• Biochemical: haemoglobin (anaemia), serum retinol, serum albumin/prealbumin, urinary iodine.
• Clinical signs: Bitot's spots (vit A), angular stomatitis (B2), bleeding gums (vit C), goitre (iodine).

High-yield: The weighment method is the most accurate diet survey technique but is costly/labour-intensive; 24-hour recall is the quickest and most commonly used in field surveys.

Complications of Imbalanced Intake

• Undernutrition: Protein-Energy Malnutrition — marasmus (energy deficit), kwashiorkor (protein deficit with oedema), and micronutrient deficiencies (anaemia, xerophthalmia, rickets, goitre).
• Overnutrition: obesity, type 2 diabetes, dyslipidaemia, hypertension, CVD — the rising "double burden of malnutrition" in India.
• Hidden hunger: micronutrient deficiency (iron, vit A, iodine, zinc, folate) despite adequate calories.

Key Differentials & Distinctions

Confused pair	Key differentiator
RDA vs EAR	RDA meets 97–98% (EAR + 2SD); EAR meets 50%
Energy RDA vs nutrient RDA	Energy set at mean (no 2SD); others at +2SD
Marasmus vs Kwashiorkor	Marasmus = severe wasting, no oedema; Kwashiorkor = oedema + fatty liver, hair changes
Visible vs invisible fat	Visible = cooking oil/ghee; invisible = fat within cereals, pulses, milk
Reference adult (ICMR-2020 65 kg) vs older 60 kg	Answer per quoted source/edition

Recently asked / exam angle

• Caloric value of fat = 9 kcal/g (vs 4 for CHO/protein, 7 for alcohol) — perennial one-liner.
• Energy increment in lactation (0–6 mo) = +600 kcal/day, pregnancy = +350 kcal/day.
• RDA = EAR + 2 SD; "for which nutrient is 2 SD NOT added?" → Energy.
• National IFA prophylaxis in pregnancy = 100 mg elemental iron + 500 µg folic acid for ≥180 days (Anaemia Mukt Bharat).
• Vitamin A prophylaxis schedule = 1 lakh IU at 9 mo, 2 lakh IU 6-monthly till 5 yr (9 doses total).
• Highest biological value protein = egg (~100).
• Cereal limiting amino acid = lysine; pulse limiting amino acid = methionine (mutual supplementation).
• Sedentary reference Indian man energy requirement ≈ 2400 kcal/day.
• "Most accurate diet survey method" → weighment method.
• Protein contributes ~10–15% and carbohydrate ~55–60% of total energy in a balanced diet.

Rapid revision

1. Fat 9, CHO 4, Protein 4, Alcohol 7 kcal/g — fat is the densest.
2. RDA = EAR + 2 SD for all nutrients except energy (energy = mean).
3. EAR meets 50%, RDA meets 97–98% of the group's needs.
4. Reference Indian adult man 65 kg / woman 55 kg (ICMR-2020); older = 60 kg man.
5. Sedentary man ≈ 2400 kcal/day; sedentary woman ≈ 1875–1900 kcal/day.
6. Adult protein RDA ≈ 0.8–1.0 g/kg → ~60 g/day; egg = highest BV (~100).
7. Pregnancy +350 kcal, lactation 0–6 mo +600 kcal ("350 bump, 600 pump").
8. Pregnancy IFA = 100 mg elemental iron + 500 µg folate × ≥180 days.
9. Vitamin A = 600 µg RE/day; prophylaxis 1 lakh IU at 9 mo then 2 lakh IU 6-monthly.
10. Vitamin C RDA (ICMR) = 40 mg/day; folate adult 300 µg, pregnancy 500–570 µg.
11. Balanced diet: CHO 55–60%, protein 10–15%, fat 20–30%; salt < 5 g, fibre 30–40 g.
12. Cereal lysine-deficient, pulse methionine-deficient → complementary proteins; weighment = most accurate diet survey.