# What Are Calories?

Everybody needs to eat to survive. People eat all kinds of foods with a wide variety of ingredients, vitamins, nutrients and other substances that are helpful for the body. One of the things many people give close attention to, though, is the number of calories a food or drink product may contain. A calorie is a unit of energy. Nearly every food and drink product contain some calories, and some have many more calories than others. Calories are usually listed as a number per serving.

Calories are usually associated with food items, but other substances contain calories as well. For example, a gallon of gasoline contains about 31,000,000 calories. (Do not drink gasoline.) Gasoline contains energy for a car and other motorized vehicles.

A calorie is the amount of energy or heat, it takes to raise the temperature of 1 gram of water 1.8 degrees Fahrenheit, and one calorie is equal to 4.184 joules, which is a common unit of energy used in physical sciences.

In addition, when calories are listed on food items, the calories are actually kilocalories because 1,000 calories = 1 kilocalorie. A food calorie contains 4,184 joules. With this in mind, a can of soda with 200 food calories listed on its label contains 200,000 regular calories. The gallon of gasoline would contain 31,000 kilocalories. If a person burns 100 calories, it actually means they burned 100 kilocalories.

Calories are necessary because they contain energy for a human to survive, which includes breathing, moving, and pumping blood. The energy humans need come from the calories in the food eaten each day. The number of calories in a food product is measured by how much potential energy the food contains.

For example, a gram of carbohydrates has 4 calories, a gram of protein has 4 calories, and a gram of fat has 9 calories. To determine the number of calories a food item contains, a person can find the number of carbohydrates, fats, and proteins a food product contains which then determines the amount of energy provided by the food. Nutritional labels of all food items show the number of calories provided by a single serving.

Once a person eats the food item, the body burns or uses the calories through metabolic processes, which break carbohydrates into glucose and other sugars, the fats into glycerol and fatty acids and the proteins into amino acids. All nutrients your body needs to survive. The molecules are then transported through the bloodstream to the cells of the body, where they are either absorbed for immediate use or sent to a final stage of metabolism where they are stored.

The number of calories needed is different for every person. The average number of calories most people need is about 2,000 per day. The food labels usually show the nutrients and vitamins needed based on a 2,000 calorie per day diet. The height, weight, gender, age, and activity level of a person determines the number of calories needed each day.

If a person takes in more calories than needed, the person will usually gain more weight. If a person does not get enough calories needed for their body, they will lose weight. However, the speed in which the body burns calories may change as well. Exercise increases a person's metabolism, which means the calories will be burned faster. In addition, some people have a higher metabolism rate than other people, even if they are not exercising.

Finally, not all calories from foods are healthy. For example, calories from carbohydrates and proteins are healthier than sources of calories from fats. An excess of fat can sometimes have serious health consequences.

A: Calories
B: Joules
C: Kilocalories
D: Ounces

A: 100 kilocalories
B: 10 kilocalories
C: 4,184 kilocalories
D: 1 kilocalorie

A: Energy
B: Fat
C: Carbohydrates
D: Fat

A: No other substance contains calories except food and drink
B: Calories are a source of energy
C: The number of calories needed for every person is different
D: Some people have a higher metabolism rate than other people

A: 4,184
B: 10 per pound
C: 2,000
D: 100,000

A: Fats
B: Proteins
C: Metabolic processes
D: Carbohydrates

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