Feeding in adulthoodThe energy needs of adulthood Proteins in adult nutrition Carbohydrates in adult nutrition Dietary fiber in adult nutrition Lipids in adult nutrition Vitamins in adult nutrition Minerals in adult feeding The water needs of the adult
- The energy needs of adulthood
- Proteins in adult nutrition
- Carbohydrates in adult nutrition
- Dietary fiber in adult nutrition
- Lipids in adult nutrition
- Vitamins in adult nutrition
- Minerals in adult nutrition
- The water needs of the adult
The energy needs of adulthood
To perform the body's vital functions (breathing, circulating blood in the blood vessels and heart, making the kidneys, liver, lungs and so on work), our body needs energy at any time of the day, even during sleep. .
This requirement is called basal metabolic rate (MB) or, in English, Basal Energy Expenditure (BEE) or also Basal Metabolic Rate (BMR), and represents the minimum energy consumption, that is what we spend when we are in the supine position, relaxed and fasting for at least 12 hours. This consumption is mainly linked to the lean body mass, therefore to the muscles, but not only; in fact the liver, the kidneys, the brain, even if they represent only a minimal percentage of our body (about 6% of body weight), are mainly responsible for the basal metabolism: in fact they account for 60%, while the muscle mass, which in adults it represents approximately 40% of body weight, it affects our basic energy needs for 18-20%.
The basal metabolic rate varies according to gender (males usually have a lean mass higher than that of females and therefore have a basal metabolic rate generally higher than age (as the years progress, there is unfortunately an increase in fat and a decrease in lean body mass), body weight and stature. It is also influenced by other factors, such as external temperature, emotional tension or physiological (pregnancy, breastfeeding) and pathological (fever, infections, diseases, etc. There is therefore a great interindividual variability.
The basal metabolic rate is measured in kilocalories / day (kcal / day) or in Chilojoule / day (kJ / day) and can be calculated quite accurately in adults, using some equations that have been developed by experts in the sector and which take into account weight, gender and age.
The total energy needs of the adult person are therefore linked primarily to the basal metabolic rate (which in a healthy and sedentary adult affects approximately 65-75% of the total energy expenditure) and to the type of diet we follow. All foods stimulate the metabolism, but not all in the same way; this stimulus, which for a normally varied diet represents 7-15% of the total energy expenditure, is called specific dynamic action (ADS) of food or even diet-induced thermogenesis (TID). This effect of food is linked to the energy necessary not only for the digestion process, but also for the absorption and assimilation of nutrients. For reasons still unclear, diet-induced thermogenesis appears to be increased by physical activity. Heat production is higher for proteins (from 10 to 35% of the total calories consumed), intermediate for carbohydrates (from 5 to 1%) and minimum for fats (from 2 to 5%), like saying that by eating, in addition to forfeiting energy with food, we consume a small amount of it. Finally, the physical activity we carry out at work or in our free time also affects our total needs. In this case, energy expenditure depends on the type, intensity and frequency of our activities and is therefore obviously very different depending on whether we are sedentary or, on the contrary, active.
Energy consumption therefore varies from a minimum quota, during sleep, to gradually increasing quotas as physical activity becomes more demanding, up to the maximum levels, for example during important sporting competitions.
Tables 9.4 and 9.5, obtained from the LARN (Recommended Energy and Nutrient Intake Levels for the Italian Population) indicate, according to the weight and type of activity carried out, range of energy demand values for adults. The lower and upper limits of caloric requirement correspond to the lower and upper values of the weight indicated in the first column. They are however purely indicative, as it is increasingly correct to rely on the subject's knowledge, and therefore on his precise weight and the type of physical activity actually carried out. An uncomplicated procedure for assessing an individual's total caloric needs (which includes basic energy requirements, linked to the type of physical activity performed), is that indicated in table 9.6. However, this has the disadvantage of not taking into account neither the sex nor the age of the subject.
It is important to remember that our weight is the result of the energy balance between demand (in fact, the basal metabolism and individual physical activity: "exits") and supply (the energy supply of the food we take on: "income").
Physical activity is therefore a fundamental tool for maintaining adequate weight. The food pyramid, proposed by the American Ministry of Agriculture, has recently been modified compared to what we are used to recognizing precisely because, with the symbol of the steps, the fundamental element of physical activity has been introduced graphically for the first time. The energy needs of a sportsman cannot be equivalent to that of an intellectual because sedentary work does not increase energy expenditure by more than 20/30% compared to our basal metabolic rate; obviously, however, it is possible to increase energy consumption by carrying out even moderate sports activities, such as regular brisk walking.
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