Nutrition, Dietetics and Lifestyle Health
Nutrition, Dietetics and Lifestyle Health tests nutrient functions, energy balance, therapeutic diets and the lifestyle advice given in outpatient and community settings.
Core rules
- Energy yield: carbohydrate 4 kcal/g, protein 4 kcal/g, fat 9 kcal/g. A balanced diet supplies energy plus protein, fat, carbohydrate, vitamins, minerals, fibre and water in proportion.
- Macronutrients: carbohydrate for energy, protein for growth and repair (1 g/kg body weight for adults, higher in burns and pregnancy), fat for essential fatty acids and fat-soluble vitamin absorption.
- Deficiencies to know: protein-energy malnutrition - marasmus (severe wasting, no oedema) and kwashiorkor (oedema, moon face, low albumin); vitamin A (night blindness, Bitot spots), vitamin D (rickets), iron (microcytic anaemia), iodine (goitre), vitamin C (scurvy).
- Therapeutic diets: diabetic (controlled carbohydrate, high fibre, low refined sugar), low sodium for hypertension and oedema, low protein with adequate energy in renal failure, high protein and high calorie in burns and tuberculosis, soft or liquid diets for chewing difficulty.
- Body mass index = weight in kg ÷ (height in metres)². Asian Indian cut-offs: 18.5–22.9 normal, 23–24.9 overweight, 25 and above obese.
- Lifestyle risk factors: tobacco, alcohol, high salt and fried food, low fruit and vegetable intake, physical inactivity, obesity and stress.
Worked example
A man weighs 78 kg and is 1.60 m tall. BMI = 78 ÷ (1.60 × 1.60) = 78 ÷ 2.56 ≈ 30.5, which is obese on Asian Indian cut-offs. Reasoning: advice should be practical and graded - reduce fried foods and sugar-sweetened drinks, add vegetables and whole grains, build up to 150 minutes of moderate activity weekly, and review rather than prescribe a crash diet.
Traps that cost marks
- Using the 25 overweight cut-off meant for Western populations.
- Confusing marasmus with kwashiorkor.
- Advising a renal patient a high-protein diet.
- Forgetting that fat gives 9 kcal/g, not 4.