Caloric intake calculation using standard Atwater physiological fuel values:

• Nutrient composition in $100\text{ g}$ food:
  Fat ($1\%$) = $1\text{ g}$
  Protein ($45\%$) = $45\text{ g}$
  Carbohydrates ($53\%$) = $53\text{ g}$
• Energy yields:
  Fat: $1\text{ g} \times 9\text{ kcal/g} = 9\text{ kcal}$
  Protein: $45\text{ g} \times 4\text{ kcal/g} = 180\text{ kcal}$
  Carbohydrates: $53\text{ g} \times 4\text{ kcal/g} = 212\text{ kcal}$
• Total caloric intake:
  $\text{Total Energy} = 9 + 180 + 212 = 401\text{ kcal}$ (commonly termed 'calories' in nutritional labelling).
  
  Option analysis:
• 661 cal: Numerical error.
• 621 cal: Numerical error.
• 401 cal: Correct total energy yield.
• 396 cal: Underestimates carbohydrate energy.