PFC ratio is a ratio of energy from Protein, Fat, and Carbohydrates, which makes up the whole energy source.

Protein, fat, and carbohydrates are the only sources of energy.

It is not a ratio of weight.
To calculate the PFC ratio, the weight (gram) shown on the nutrition facts table needs to be converted to energy (kcal).
Protein 1g = 4kcal, fat 1g = 9kcal, carbohydrate 1g = 4kcal

Carbohydrate 1g can range approximately between 3.85～4.2kcal depending on the food.

Ex.1 1 cup of Brand A whole milk (200mL)
Nutrition Facts Table (g) Converted to energy (kcal) P:F:C
Energy 132 kcal (Total approx. 132 kcal) (Total 100)
Protein 6.6g 26.4 kcal 20
Fat 7.4g 66.6 kcal 50
Carbohydrates 9.7g 38.8 kcal 30

As seen in the table above, the PFC ratio of this whole milk is 20:50:30, which is the approximate average P:F:C balance of Japanese patients’ diet. This ratio is also regarded as a good nutritional balance for citrin deficiency patients in Japan. Please consult your doctor for the appropriate PFC balance.

Ex.2 1 small bowl of Brand Z white rice (100g)
Nutrition Facts Table (g) Converted to energy (kcal) P:F:C
Energy 168 kcal (Total approx. 168 kcal) (Total 100)
Protein 2.5g 10.0 kcal 6
Fat 0.3g 2.7 kcal 2
Carbohydrates 37.1g 155.3 kcal 92

As seen in the table above, the PFC ratio of this bowl of rice is 6:2:92. Patients are advised to combine other dishes that are high in protein and fat to balance the nutrient intake of the whole meal so that it is closer to a high protein, high fat and low carbohydrate diet.

To find out more about the nutritional data of different foods, please visit USDA’s FoodData Central here: https://fdc.nal.usda.gov/