Define calories and explain how the body gets energy.
Calories are a unit of measurement used to quantify the amount of energy provided by food and beverages. It represents the energy content that can be released during the process of digestion and metabolism in the body.
The body gets energy through the process of metabolism. When we consume food, our digestive system breaks down the complex molecules into simpler forms such as carbohydrates, proteins, and fats. These macronutrients contain carbon atoms that can be oxidized or utilized by our cells to release energy.
Carbohydrates are the primary source of energy for the body. They are broken down into glucose, which enters the bloodstream and is transported to cells to be utilized for energy production. Glucose can be immediately used as fuel, or it can be converted and stored as glycogen in the liver and muscles for later energy use.
Proteins can also provide energy when needed. They are broken down into amino acids, which can be converted to glucose through a process called gluconeogenesis. Alternatively, amino acids can be used for protein synthesis and other vital functions in the body.
Fats, although often associated with weight gain, are an essential energy source. During digestion, fats are broken down into fatty acids and glycerol. These can be used for immediate energy needs or stored in adipose tissue for long-term energy storage.
Alcohol, although not a nutrient, also provides calories. It is metabolized similarly to fat, releasing energy during the breakdown process.
Overall, the body extracts energy from food by breaking down macronutrients into simpler forms that can be utilized by cells. The energy released is then used for various bodily functions, including physical activity, maintaining body temperature, supporting organ functions, and even at rest.