Our body needs energy for its metabolic and physiological functions. It gets its energy from food and its macronutrient constituents, i.e. carbohydrates, fats and proteins. Dietary energy intake from food must meet the requirements for achieving and maintaining optimal health, physiological function and well-being.
Energy requirements are the amount of food energy needed to maintain body size, body composition, and a necessary level of physical activity consistent with long-term good health. Dietary energy requirements cannot be considered in isolation from other nutrients in the diet, as a lack of one element will influence the others. Thus, energy needs must be met by consuming a diet that satisfies all nutrient needs.
Mitochondria are found in the cytoplasm of all eukaryotic cells, i.e. cells with a clearly defined nucleus. Their main function is to generate large amounts of energy in the form of adenosine triphosphate (ATP). The number of mitochondria per cell varies greatly.
ATP, the energy-carrying molecule, is found in the cells of all living things. When ATP is broken down, energy is released which can be harnessed for cellular work. Because ATP is so easily broken down and reformed, ATP is like a rechargeable battery that powers cellular processes.
ATP is often referred to as the “molecular unit of currency” of intracellular energy transfer. ATP captures energy obtained from the breakdown of food and releases it to fuel cellular processes. Our body regenerates and recycles its own equivalent body weight in ATP every day.
Daily energy needs –
There are only small amounts of ATP in the body. Therefore, it is necessary to have sufficient power reserves for backup. The amount of energy needed daily depends on an individual’s daily energy intake and metabolic energy requirements, which depend on body weight and activity level.
The energy we get from food to fuel our bodies is measured in kilojoules. Fats, carbohydrates and proteins, found in food, all provide energy.
The basic energy consumption of the human body is 4 kJ/kilogram of body weight per hour daily. Thus, the basic energy consumption of an individual can be calculated as follows:
Total energy consumption = Body weight (Kg) × 4 KJ × 24 hours/day / 4.18 kJ
The total energy consumption value is divided by 4.18 kJ to convert the value to kilocalories (1 kcal = 4.18 kJ). This calculation represents the daily energy consumption.
Individual energy needs vary by age, sex, size and activity level. Excess food intake that is not used as energy can be stored in the body as fat. Excess fat storage can lead to a high body mass index (BMI).
BMI indicates a person’s body fat and is determined by an individual’s height and weight. In adults, the normal suggested BMI is between 19 and 24. A high BMI can potentially lead to disease or health complications. In order to have an ideal BMI, an individual’s energy intake should not exceed the energy expended on a regular basis.
Energy balance –
Energy balance is the relationship between the calories taken in by the body through food and drink and the calories used by the body for our daily energy needs.
When you take in more calories than you take in, you are in positive energy balance. When you ingest fewer calories than you consume, you are in a negative energy balance. Your energy balance affects your metabolism, hormonal balance, and mood.
A negative energy balance leads to weight loss. The body detects an energy deficit and fat reserves are called upon to make up the difference. A positive energy balance has its own ramifications not only in terms of weight gain, but also in terms of health and fitness.
The conclusion –
The metabolic and physiological functions of our body require energy, which is produced from the food we eat. Mitochondria present in the cytoplasm of all eukaryotic cells generate large amounts of energy in the form of ATP. Our body generates its own body weight equivalent of ATP every day. Individual energy needs vary by age, sex, size and activity level.