Nutrition, Diet and Common Health Conditions
This domain tests the balanced diet, nutrient deficiencies, body-mass index and the diet changes made in common diseases.
Balanced diet and nutrients
A balanced diet supplies energy, protein, fat, vitamins, minerals, fibre and water in the right proportion. Energy foods are cereals, roots and sugars; body-building foods are pulses, milk, egg, fish and meat; protective foods are vegetables and fruits. ICMR-NIN recommends plenty of vegetables and fruit, whole grains, limited oil, salt below 5 g a day and free sugar below 5% of energy.
Deficiency diseases to memorise
- Vitamin A → night blindness and xerophthalmia.
- Vitamin B1 → beriberi; B3 → pellagra; B12/folate → megaloblastic anaemia.
- Vitamin C → scurvy; Vitamin D → rickets in children, osteomalacia in adults.
- Iron → iron-deficiency anaemia; iodine → goitre.
- Protein-energy malnutrition → marasmus (severe wasting) and kwashiorkor (oedema, low protein).
Body mass index
BMI = weight in kg ÷ (height in metres)². Asian cut-offs: under 18.5 underweight, 18.5–22.9 normal, 23–24.9 overweight, 25 and above obese.
Therapeutic diets
Low salt in hypertension and heart failure; low protein with adequate energy in chronic kidney disease; high protein and high calorie in burns and tuberculosis; carbohydrate-controlled, high-fibre diet in diabetes; soft or liquid diet after surgery.
Worked example
A person weighs 60 kg and is 1.60 m tall. BMI = 60 ÷ (1.60 × 1.60) = 60 ÷ 2.56 = 23.4. By Asian cut-offs this is overweight (23–24.9), even though it would be called normal on the older WHO cut-off of 25. Reasoning is the formula plus the correct cut-off table, not a guess.
Traps that cost marks
- Mixing the BMI cut-off tables.
- Advising tea or coffee with iron tablets - tannins reduce absorption; pair iron with vitamin C instead.
- Preparing ORS with the wrong amount of water; always follow the packet instruction.