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