Nutritional facts of Energy

Nutritional facts of Energy

1. Energy Mrs.Nagamani.T , MSc (N) HOD, Dept.of Community Health Nursing

2. Introduction Nutrition is the science of food and its relationship to health – how the human body uses food and processes the nutrients it contains to enable the body to perform functions (i.e. the heart to beat, the lungs to breathe, the kidneys to filter blood, the brain to think etc .). Energy is the capacity to do work . Through the process of digestion, we convert the food we eat to energy. Our bodies need energy to grow and repair themselves, keep warm and do physical activity. Energy comes from food and drink, in particular from carbohydrates, protein, fat and alchol .

3. Definition Energy is defined as the capacity to do work . Energy is the strength and vitality required for sustained physical or mental activity.  Energy requirement  is the amount of food energy needed to balance energy expenditure in order to maintain body size, body composition and a level of necessary and desirable physical activity consistent with long-term good health. This includes the energy needed for the optimal growth and development of children, for the deposition of tissues during pregnancy, and for the secretion of milk during lactation consistent with the good health of mother and child.

4. Unit of energy The food energy is calculated as Calories (C) or kilocalories (kcal) or Joules (J). Calorie; The qualitative food requirements are estimated in terms of energy in Calorie. One kilocalorie is equal to 1000 calories. One Kcal is equal to 4.186 Joules One gram of protein or carbohydrate provides 4 kcal whereas one gram of fat provides 9 kcal. In nutrition calorie and kilocalorie are sometimes used to mean the same thing.

5. Energy requirement of different categories of people The recommended level of dietary energy intake  for a population group is the mean energy requirement of the healthy, well-nourished individuals who constitute that group.

6. COMPONENTS OF ENERGY REQUIREMENTS Human beings need energy for the following: Basal metabolism . This comprises a series of functions that are essential for life, such as cell function; the synthesis, secretion and metabolism of enzymes and hormones to transport proteins and other substances; the maintenance of body temperature; uninterrupted work of cardiac and respiratory muscles; and brain function. Basal metabolic rate (BMR) :  The minimal rate of energy expenditure compatible with life. It is measured in the supine position under standard conditions of rest, fasting, immobility, thermoneutrality and mental relaxation. Depending on its use, the rate is usually expressed per minute, per hour or per 24 hours. Depending on age and lifestyle, BMR represents 45 to 70 percent of daily total energy expenditure, and it is determined mainly by the individual’s age, gender, body size and body composition .

7. Metabolic response to food . Eating requires energy for the ingestion and digestion of food, and for the absorption, transport, inter conversion , oxidation and deposition of nutrients. These metabolic processes increase heat production and oxygen consumption, and are known by terms such as  dietary-induced thermogenesis ,  specific dynamic action of food  and  thermic effect of feeding . The metabolic response to food increases total energy expenditure by about 10 percent of the BMR over a 24-hour period in individuals eating a mixed diet. Physical activity . This is the most variable and, after BMR, the second largest component of daily energy expenditure. Humans perform  physical activities.

8. Discretionary activities , include the regular practice of physical activity for fitness and health; the performance of optional household tasks that may contribute to family comfort and well-being; and the engagement in individually and socially desirable activities for personal enjoyment, social interaction and community development . Growth . The energy cost of growth has two components: 1) the energy needed to synthesize growing tissues; and 2) the energy deposited in those tissues. The energy cost of growth is about 35 percent of total energy requirement during the first three months of age, falls rapidly to about 5 percent at 12 months and about 3 percent in the second year, remains at 1 to 2 percent until mid-adolescence, and is negligible in the late teens.

9. Pregnancy . During pregnancy, extra energy is needed for the growth of the foetus , placenta and various maternal tissues, such as in the uterus, breasts and fat stores, as well as for changes in maternal metabolism and the increase in maternal effort at rest and during physical activity. Lactation . The energy cost of lactation has two components: 1) the energy content of the milk secreted; and 2) the energy required to produce that milk. Well-nourished lactating women can derive part of this additional requirement from body fat stores accumulated during pregnancy.

10. BMI ( Body Mass Index) Body mass index (BMI) is an estimate of body fat based on height and weight. It doesn’t measure body fat directly, but instead uses an equation to make an approximation. BMI can help determine whether a person is at an unhealthy or healthy weight . Body Mass Index Formula BMI is calculated by dividing a person’s weight by the square of their height . BMI Weight Status Below 18.5 Underweight 18.5 – 24.9 Normal 25.0 – 29.9 Overweight 30.0 and above Obese Adults age 20 and older can interpret their BMI based on the following standard weight status categories. These are the same for men and women of all ages and body types:

11. BMI

12. Body Mass Index for Children; BMI is interpreted differently for people under age 20.The implications for children and adolescents can vary depending on age and gender. The amount of body fat changes with age. It’s also different in young boys and girls. Girls usually acquire a higher amount of body fat and develop it earlier than boys . For children and teens, the CDC uses  age growth chartsTrusted Source  to show BMI as a percentile ranking. Each percentile expresses a child’s BMI relative to other children of the same age and gender. For example, a child would be considered obese if they had a BMI that landed at or above the 95th percentile. This means that they have more body fat than 95 percent of children in the same age and gender category.

13. Percentile Weight Status Below 5th Underweight 5th to 85th Normal or healthy weight 85th to 95th Overweight 95th and above Obese The following table shows the percentile range for each weight status :

14. For children and teens, BMI is age- and sex-specific and is often referred to as BMI-for-age. In children, a high amount of body fat can lead to weight-related diseases and other health issues. Being underweight can also put one at risk for health issues. A high BMI can indicate high body fatness. BMI does not measure body fat directly, but BMI is correlated with more direct measures of body fa

15. Determinants and factors affecting basal metabolic rate/ Energy Expenditure 1. Muscle mass.  The amount of muscle tissue on the body . Muscle requires more energy to function than fat. So the more muscle tissue the body carry, the more energy body needs just to exist. (Resistance or strength training is most effective for building and maintaining mass.) 2.  Age.  As we get older, metabolic rate generally slows. This is because of a loss of muscle tissue and changes to hormonal and neurological processes. During development children go through periods of growth with extreme rates of metabolism. 3.  Body size.  Those with bigger bodies have a larger BMR because they have larger organs and fluid volume to maintain. 4.  Gender.  Men generally have faster metabolisms than women. 5.  Genetics.  Some families have faster BMR than others with some genetic disorders also affecting metabolism.

16. 6.  Physical activity.  Exercise increases muscle mass and powers up metabolic engines burning kilojoules at a faster rate, even when at rest. 7.  Hormonal factors.  Hormonal imbalances such as hypo & hyperthyroidism can affect metabolism . 8.  Environmental factors.  Environmental changes such as increased heat or cold forces the body to work harder to maintain its normal temperature and increases BMR. 9.  Drugs.  Caffeine and nicotine can increase BMR while medications such as antidepressants and steroids increase weight gain regardless of what we eat . 10.  Diet.  Food changes the body’s metabolism. What and how we eat has a big influence on BMR .

17. Normal BMR value An average man has a  BMR of around 7,100 kJ per day , while an average woman has a BMR of around 5,900 kJ per day. Energy expenditure is continuous, but the rate varies throughout the day. The rate of energy expenditure is usually lowest in the early morning.

18. Energy Value of Some Foods

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