Explanation: In the context of nutrition and food science, energy from food is quantified using the unit called a calorie. A calorie is defined as the amount of energy required to raise the temperature of one gram of water by one degree Celsius. In nutritional contexts, the term "calorie" often refers to a kilocalorie (kcal), which is the energy needed to raise the temperature of one kilogram of water by one degree Celsius.
Calories are a universal unit of energy measurement in the field of nutrition. They are used to describe the energy content of food and beverages, as well as the energy expenditure of the human body. The energy from food is essential for various bodily functions, including metabolism, physical activity, and maintaining body temperature.
It is important to understand that while carbohydrates, proteins, and fats are the primary macronutrients that provide energy, the energy they provide is measured in calories. Each gram of carbohydrate and protein provides approximately 4 calories, while each gram of fat provides about 9 calories. This means that the total energy content of a food item is calculated based on the amount of these macronutrients it contains, and this total energy is expressed in calories.
In the context of Indian General Knowledge (GK), understanding the concept of calories is crucial for various competitive examinations, as it forms a part of basic nutrition and health-related questions. It is also relevant in discussions about diet, nutrition, and health, which are often topics in GK sections of exams.
To summarize, while carbohydrates, proteins, and fats are the sources of energy in food, the energy itself is measured in calories. Therefore, the correct answer to the question "Energy from food is called" is (D) Calories.