Final answer:
Food energy is measured in calories; proteins and carbohydrates provide about 4 Calories per gram, while fats provide around 9 Calories per gram. Nutritional labels help determine the energy content from these macronutrients. Excess carbohydrates are stored as glycogen or fat for energy.
Step-by-step explanation:
How is Food Energy Measured?
Food energy is measured in calories, which represent the amount of energy required to raise the temperature of 1 kilogram of water by 1 degree Celsius. In the context of food, calories are used to express the energy content. During digestion, food is broken down into chemical components, which the body can then convert into usable energy.
Energy Yield from Macronutrients
The macronutrients in food are proteins, carbohydrates, and fats or oils. Proteins and carbohydrates each provide about 4 Calories per gram, while fats and oils provide about 9 Calories per gram. Nutritional labels on food packages display the caloric content of one serving, along with the breakdown of calories from each of these macronutrients.
Excess Carbohydrates and Energy Storage
Excess carbohydrates are converted into glycogen and stored in the liver and muscles for short-term energy needs. When these stores are full, additional excess energy is converted into fat and stored in adipose tissues as long-term energy reserves.