Biology · Ch 14 — Human Nutrition
Calorific and Physiological Value of Food
14.5.4
Calorific and Physiological Value of Food
The energy content of food can be measured in two related ways. The gross calorific (gross energy) value is the amount of heat released when 1 gram of a food is completely burned (combusted) in a bomb calorimeter. However, the body cannot extract quite all of this energy during digestion and metabolism, so the physiological value — the energy actually produced by 1 gram of food inside the body — is somewhat lower. For the three main food components, these values are approximately:
| Food component | Gross calorific value (Kcal/g) | Physiological value (Kcal/g) |
|---|---|---|
| Fats | 9.45 | 9.0 |
| Proteins | 5.65 | 4.0 |
Table 14.5.4Gross Calorific and Physiological Value of Food Components
Fats: Gross calorific value 9.45 Kcal/g; Physiological value 9.0 Kcal/g.
Proteins: Gross calorific value 5.65 Kcal/g; Physiological value 4.0 Kcal/g. …