Nutrition and Dietetics: Nutrients, BMI, and Therapeutic Diets
What this domain tests
Questions cover nutrients, balanced diets, energy, BMI, deficiency diseases, and therapeutic diets.
Core rules and concepts
- Macronutrients: carbohydrates (4 kcal/g), protein (4 kcal/g), fat (9 kcal/g). Alcohol is not a nutrient but gives 7 kcal/g.
- A balanced diet supplies energy, protein, vitamins, minerals, fibre, and water in correct proportions.
- BMI = weight (kg) / height (m)². Adult Asian cut-offs: underweight <18.5, normal 18.5–22.9, overweight 23–24.9, obese ≥25.
- Iron absorption is increased by vitamin C and decreased by tea/coffee and phytates.
- Fat-soluble vitamins A, D, E, K; water-soluble B complex and C.
- Diabetic diet: high fibre, complex carbohydrates, limited refined sugar, regular meal timing.
Worked example
A woman weighs 60 kg and is 1.5 m tall. BMI = 60 / (1.5 × 1.5) = 60 / 2.25 = 26.7 kg/m². Reasoning: square the height first, then divide. Using Asian cut-offs, 26.7 is obese. The nurse should assess diet, activity, and comorbidities rather than only advising weight loss.
Traps that cost marks
- Forgetting to square height.
- Using centimetres directly instead of metres.
- Calling vitamin C fat-soluble.
- Recommending tea with iron tablets.