Ad
related to: kilojoules per gram of carbohydrate conversion to table definition
Search results
Results From The WOW.Com Content Network
Proteins and most carbohydrates have about 17 kJ/g (4 kcal/g), though there are differences between different kinds. For example, the values for glucose, sucrose, and starch are 15.57, 16.48 and 17.48 kilojoules per gram (3.72, 3.94 and 4.18 kcal/g) respectively.
The unit is most commonly used to express food energy, namely the specific energy (energy per mass) of metabolizing different types of food. For example, fat (triglyceride lipids) contains 9 kilocalories per gram (kcal/g), while carbohydrates (sugar and starch) and protein contain approximately 4 kcal/g. [29] Alcohol in food contains 7 kcal/g. [30]
Fat has a food energy content of 38 kilojoules per gram (9 kilocalories per gram) proteins and carbohydrates 17 kJ/g (4 kcal/g). [2] Water makes up a large proportion of the total mass ingested as part of a normal diet but it does not provide any nutritional value.
A moderate energy density would be 1.6 to 3 calories per gram (7–13 kJ/g); salmon, lean meat, and bread would fall in this category. Foods with high energy density have more than three calories per gram (>13 kJ/g) and include crackers, cheese, chocolate, nuts, [10] and fried foods like potato or tortilla chips.
Glucose is the human body's key source of energy, through aerobic respiration, providing about 3.75 kilocalories (16 kilojoules) of food energy per gram. [106] Breakdown of carbohydrates (e.g., starch) yields mono- and disaccharides, most of which is glucose.
Carbohydrates and proteins provide 17 kJ approximately (4 kcal) of energy per gram, while fats provide 37 kJ (9 kcal) per gram. [8] However, the net energy derived from the macronutrients depends on such factors as absorption and digestive effort, which vary substantially from instance to instance.
Based on the work of Atwater, it became common practice to calculate energy content of foods using 4 kcal/g for carbohydrates and proteins and 9 kcal/g for lipids. [2] The system was later improved by Annabel Merrill and Bernice Watt of the USDA, who derived a system whereby specific calorie conversion factors for different foods were proposed. [3]
Energy released by the metabolism of 1 gram of carbohydrates [103] or protein [104] 3.8×10 4 J: Energy released by the metabolism of 1 gram of fat [105] 4–5×10 4 J: Energy released by the combustion of 1 gram of gasoline [106] 5×10 4 J: Kinetic energy of 1 gram of matter moving at 10 km/s [107] 10 5 3×10 5 – 15×10 5 J