Table 2: Sample calculations of daily energy requirements for the 3 : 1 classic ketogenic diet for a 18 kg patient.
 Daily caloric requirement (i) Total body weight × 68 cal/kg/day (ii) 18 kg × 68 cal/kg/day = 1224 cal/day Daily number of dietary units (i) For 3 : 1 (fat : protein/carbohydrate) (a) 3 g fat/unit × 9 cal/g fat → 27 calories (b) 1 g protein or CHO/unit × 4 cal/g protein or carbohydrate (CHO) = 4 calories (c) 27 + 4 = 31 calories/unit (ii) Daily caloric requirement ÷ calories/unit = dietary units/day (a) 1224 ÷ 31 = 39 units/day Daily fat content (i) Dietary units/day × g fat/unit = g fat/day (ii) 39 units/day × 3 g fat/unit = 117 g fat/day Daily protein and CHO content (combined) (i) Dietary units/day × g protein or CHO/unit = g protein or CHO/day (ii) 39 units/day × 1 g protein or CHO/unit = 39 g protein and CHO/day Daily protein content = 1 g/kg/day (i) 1 g/kg/day × 18 kg = 18 g/day Daily carbohydrate content (i) Combined protein and CHO content − daily protein content = daily carbohydrate content (ii) 39 g protein and CHO/day − 18 g protein/day = 21 g CHO/day Divide allotment into 3 meals (i) Fat: 117 ÷ 3 = 39 g/meal (ii) Protein: 18 ÷ 3 = 6 g/meal (iii) CHO: 21 ÷ 3 = 7 g/meal