Food energy

Food energy denotes the energy essential for the survival and function of all living organisms, notably animals and humans. This energy is harnessed from consumed food and is pivotal in various physiological processes, especially cellular respiration. Cellular respiration can be categorized into two main processes: aerobic respiration, where oxygen combines with food molecules, and anaerobic respiration, which involves the reorganization of atoms within the molecules.

Basics of Food Energy

For efficient functioning, humans and other living beings require a consistent intake of food energy. This energy powers the body's metabolism and enables muscular activity. The primary constituents of food include carbohydrates, fats, proteins, water, vitamins, and minerals. A majority of a food item's weight is composed of carbohydrates, fats, proteins, and water. Interestingly, vitamins and minerals only account for a minuscule fraction of the food's weight. As a statistical fact, carbohydrates, fats, and proteins form around ninety percent of the dry weight of most foods.

The energy we extract from our food primarily comes from carbohydrates, fats, and proteins. Other constituents such as organic acids, polyols, and ethanol, which are present in our diet, also contribute to our energy intake. Although some components like water, vitamins, minerals, cholesterol, and fiber might not directly contribute much energy, they hold paramount importance for health, vitality, and survival. For instance, fiber, a subtype of carbohydrates, isn't entirely digestible by humans. However, Ruminants, with the aid of bacteria in their rumen, can harness energy by respiring cellulose.

Measurement Units

In the realm of the International System of Units, energy is quantified in joules (J) and its larger unit, the kilojoule (kJ), is most commonly associated with food energy. Historically and still prevalent in certain contexts, the calorie is employed to denote energy in food. It's essential to distinguish between the "food calorie" or the kilocalorie (kcal or Cal), equivalent to 4.184 kilojoules, and the "small calorie" (cal) commonly used in chemistry and physics. This differentiation is especially pertinent in regions like the European Union, where both "kcal" and "kJ" are featured on nutrition labels. In nations such as the US and Canada, the term "calorie" or "Calorie" is exclusively used.

Different components in food have varied energy densities. Fats and ethanol provide the maximum energy by mass, 37 and 29 kJ/g respectively. In comparison, proteins and most carbohydrates deliver approximately 17 kJ/g (4.1 kcal/g) . The energy density difference among food components (like fats, alcohols, and carbohydrates) mainly stems from their individual atomic proportions of carbon, hydrogen, and oxygen. Some carbohydrates, which are not easily absorbed like fiber or lactose in lactose-intolerant individuals, give less energy. Similarly, Polyols and organic acids contribute about 10 kJ/g (2.4 kcal/g)

and 13 kJ/g (3.1 kcal/g)
respectively. Factors like water content, fat percentage, and fiber in foods can influence their energy density.

Conventionally, food energy measurements rely on the heat produced during oxidation reactions in a bomb calorimeter. Additional corrections consider the efficiency of digestion, absorption, and urinary excretions like urea. The foundational work on these measurements can be traced back to the late 19th century, thanks to the endeavors of the American chemist Wilbur Atwater. The detailed methodology is elaborated in the Atwater system.

The energy one can harness from food, termed the "metabolizable energy intake (MEI)," can be calculated approximately by multiplying a food item's total energy by 85%. This percentage typically represents the energy acquired by a human post-respiration. Animal nutrition often emphasizes this energy parameter due to its significance in meat production economics.

Nutrition Labels

Nutrition facts displayed on a Basmati rice packet in the United Kingdom

Nutrition labels serve as a vital source of information, allowing consumers to comprehend the nutritional content of food products. These labels detail the energy content, often in both kilojoules and kilocalories, and offer a breakdown of the primary nutrients, facilitating informed food choices.

Summary

Understanding food energy is critical for both individual health and broader societal wellbeing. As we make dietary choices, being informed about the energy content and its source can guide healthier and more sustainable consumption patterns.

Food energy Resources
Need Help Finding a Doctor? Need help finding a doctor or specialist anywhere in the world? Explore our world directory. WikiMD's DocFinder can assist you in locating millions of physicians.	Medical Knowledge Access the latest research - Most recent articles Ongoing trials.

Translate to: East Asian 中文, 日本, 한국어, South Asian हिन्दी, Urdu, বাংলা, తెలుగు, தமிழ், ಕನ್ನಡ,
Southeast Asian Indonesian, Vietnamese, Thai, မြန်မာဘာသာ, European español, Deutsch, français, русский, português do Brasil, Italian, polski