Energy - Unit 1 PDF

Basic Nutrition - Energy and Macronutrients  Energy Energy is defined as "the capacity to do work.“ Sun – The ultimate source of energy. Energy – First and foremost function of food. Energy must be supplied regularly to meet the energy needs for the body...

Basic Nutrition - Energy and Macronutrients  Energy Energy is defined as "the capacity to do work.“ Sun – The ultimate source of energy. Energy – First and foremost function of food. Energy must be supplied regularly to meet the energy needs for the body's survival. Why energy is important? Maintenance of basal body functions (basal metabolism) Maintenance of Body Weight and Physical activity Growth and development in infants and children and maintenance of pregnancy and lactation in women.  Forms of ENERGY Light Energy Solar Energy Food Chemical Energy Electrical Mechanical Heat All living cells Energy Energy Energy Brain and Nerve cells Muscle cells  Forms of ENERGY (Cont..) 1. CHEMICAL ENERGY in FOOD 2. SOLAR ENERGY for Vit D synthesis in skin and for photosynthesis in plants 3. MECHANICAL ENERGY for movement of muscles 4. ELECTRICAL ENERGY for functioning of Brain & NERVE CELLS 5. HEAT ENERGY, generally produced when energy is converted from one form to another. 6. Energy from food is converted into heat energy 7. Interconvertible  How we get energy from food? Glucose Oxygen CO2 +H2O+ENERGY Fatty acids Amino Acids Energy from food is stored as ATP, Living cells only uses this form of energyGlucose ATP ADP + 8 KCal  Energy Requirement An adequate, healthy diet must satisfy human needs for energy and all essential nutrients Definition - 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.  ASSESSMENT OF ENERGY REQUIREMENTS Currently, it is recommended that energy requirement must be assessed in terms of energy expenditure rather than in terms of energy intake. Energy intake may vary from day to day; On some days, it may be above the energy expenditure and sometimes, below it. Body energy reserves (viz., fat) help to maintain normal energy expenditure over short periods even when the daily intake is below expenditure.  ESTIMATES OF ENERGY REQUIREMENTS Energy requirement of adult is determined from energy expenditure for basal metabolism and for activity, each contributing to approximately half of the total daily energy expenditure. EER – Derived from measurements of a collection of individuals of the same gender and similar age, body size and Physical activity – Grouped together to give average ER. Energy expended during sleep, rest and occupational and non- occupational activities during 24 hrs. are added up to arrive at the total daily expenditure.  ESTIMATES OF ENERGY REQUIREMENTS Energy requirement of adult is determined from energy expenditure for basal metabolism and for activity, each contributing to approximately half of the total daily energy expenditure. EER – Derived from measurements of a collection of individuals of the same gender and similar age, body size and Physical activity – Grouped together to give average ER. Energy expended during sleep, rest and occupational and non- occupational activities during 24 hrs. are added up to arrive at the total daily expenditure.  Recommendation on Energy Requirement Total energy requirement or Total energy expenditure (TEE) is calculated based on a multiplication of basal metabolic rate (BMR) to physical activity level (PAL): TEE = BMR X PAL Measured directly (using DLW or HRM methods), by FAO/WHO/UNU or predicted from body weight, gender and age specific equations by FAO/WHO/UNU The ICMR (2020) expert group – Recommended a 10% and 9% reduction in BMR with simultaneous reduction in PAL. Hence recommended energy requirement reduced 3 to 8 kcal/kg/day for adults compared with RDA 2010.  Energy Requirement of Infants (0-12 months) ER very high – Infancy – A period of very rapid growth. ER for infants – TEE + Energy needs for growth. Energy needs are highest during first 3 months & fall over next 6 months when growth rates are lower. Rises again after 9 months as child becomes physically active. Energy/Body Weight Net Energy(Kcal/d) Body weight (Kg) 0 -6 months ~ 98/Kcal/Kg/d 530 5.8 6 – 12 months 80/Kcal/Kg/d 680 8.5 Source: RDA and EAR 2020, ICMR-NIN  Energy Requirement of Children & Adolescents Preschool – 1 to 6 years Variability in energy requirement exists because of the variation in growth and physical activity. Energy needs for Growth – Energy used to synthesise growing tissues & Energy deposited in those tissues. Adolescent – 10 to 18 years  Energy Requirement of Adults Energy needs of Indian men and women for different activity levels computed on the basis of recommendations made by ICMR(2020) expert group. For computing RDA, the ICMR has taken “Reference Man” body weight as 65kg and “Reference Woman” as 55kg. Sex Ref Body weight Energy (EAR) Activity category Energy based on Ref. Body weight Man 65 Sedentary 2320 Moderate 2710 Heavy 3470 Woman 55 Sedentary 1660 Moderate 2130 Heavy 2720 Source: RDA and EAR 2020, ICMR-NIN  Energy Requirement during Pregnancy ER of Pregnancy are those needed for adequate maternal gain to ensure growth of the fetus, Placenta and associated maternal tissues and increased metabolic demands of pregnancy, Energy to maintain adequate maternal weight, body composition and physical activity and Energy stores to assist in lactation after delivery. BMR increases due to tissue synthesis, increases tissue mass, cardiovascular & respiratory work For Pregnancy weight gain of 10 – 12Kg  Energy Requirement during Lactation ER of lactating women is defined as level of energy intake from food that will balance the energy expenditure needed to Maintain body weight and composition Physical activity Breastmilk production Maintain Consistent good health for woman and her child Economically necessary and socially desirable activities. Undernourished woman & those with insufficient gestational weight gain should increase food intake by 675Kcal/day for 1st 6 months  RECOMMENDED DIETARY ALLOWANCES(RDA) It is defined as levels of intake of the essential nutrients that are to be sufficient to meet the nutrient requirement of nearly all healthy individuals in a particular life stage and gender group. Amount of the nutrient sufficient for the maintenance of health in nearly all people. For all nutrients, except energy, RDA= minimum requirement + safety margin RDA doesn’t apply to sick people. FACTORS THAT EFFECT RDA RDA of an individual depends on many factors like: Age Sex Physical work- sedentary, Moderate, Hard (heavy) Physiological stress Pregnancy lactation  RDA FOR INDIANS ICMR has defined well nourished Indian adults who had satisfactory growth during childhood. Scientists have prescribed RDA for adults, depending on the level of activity of individual. Sedentary workers: those who sit & work using brain & hands. Eg: teachers, clerks, typists, officers. Moderate workers: those who work vigorously for a few hours using many parts of the body like hands, feet & muscles. Eg: postman, mali, servant, housewife doing all household work. Heavy workers: use different parts of body for several hours. Eg: rickshaw pullers, coolies, workers in mines, sports person, masons etc Reference man: between 20-39 yrs of age, Weighs 65kg, Free from disease & physically fit for active work, Employed for 8hrs, 4-6 hrs sitting & moving about, 2hrs in walking or household duties, 8hrs in bed Reference woman: Between 20-39 yrs of age, Healthy & weighs 55kg, May be engaged 8hrs in general household work or in light industry or in any other moderately active work, 8hrs in bed, Spends 4-6hrs sitting or moving around in light activity, 2hrs walking or active recreation or household.  Energy Imbalance Energy balance is achieved when input(dietary energy intake) is equal to output(total energy expenditure). When energy balance is maintained for prolonged period of time, an individual is considered to be in a steady state. Too much deviation on either side from the appropriate range of body weight increases risk of health problems Over weight → Positive energy balance Underweight → Negative energy balance  Body Mass Index BMI – Predictor of the impact of body weight on morbidity and mortality risks. Morbidity - defined as the state of having a disease or medical condition. Mortality –defined as number of deaths that occur in a population. Body Mass Index – defined as weight in kilograms divided by the square of height in meters. BMI – also called Quetelet’s index Body Mass Index  Consequences - Energy Imbalance Common way to assess undernutrition or overnutrition is in terms of body weight. Undernutrition – less than adequate intake of nutrients (Energy). In adults its called “energy deficiency” Overnutrition/ obesity – Energy intake exceeds energy expenditure  Chronic Energy Deficiency Energy deficiency Refers to less than adequate intake of energy. Further subclassified into acute and chronic energy deficiency. Acute energy deficiency – Involuntary weight loss of greater than 10% of body weight occurs over a 3 -6 months. Its sudden and associated with declining body weight. Chronic Energy Deficiency – occurs over a period of long time. Stable decrease in body weight. Characterised by low BMI in weight stable individuals Chronic Energy Deficiency What happens in negative energy balance? NEGATIVE ENERGY BALANCE  Obesity Global chronic health problem in adults – emerge as more serious world problem than undernutrition by 2025 – WHO. Obesity – imbalance in energy intake and energy expenditure. Cause – Alterations in lifestyle and dietary intake have led to the increasing incidence of obesity and NCDs. Risk factors – genetics, food intake, physical inactivity and some rare metabolic diseases. In order to promote general health, at least 30 mins of moderate to vigorous activity should be performed, three or more days per week – FAO/WHO/UNU 2004  Obesity In view of the known adverse health consequences of both excess and deficient energy intake, it is essential that appropriate recommendation of RDA for Indians if evolved. This is important as the country is entering an era of dual disease burden of CED and infections on the one hand and that of obesity and non-communicable diseases on the other.  Consequences -Obesity Brain: Fat deposits accumulate in the arteries of the brain leading to blood clots and brain strokes. Airways and Lungs: Overweight people are more likely to develop breathing difficulties such as asthma and obstructive sleep apnea where the airway collapses during sleep. Heart and arteries: Since the heart has to pump harder to sustain a heavier person, it naturally increases blood pressure which can trigger a heart attack or stroke. Also, fat deposits in the arteries can eventually lead to an angina, heart attack or cardiac arrest. Liver and Gall bladder: Overweight people are more prone to liver conditions such as cirrhosis and hepatitis as well as gall bladder stones. Kidneys and bladder: Obese people are more at risk from kidney failure and kidney cancer. They are also more prone to stress incontinence (leaking urine) or urge incontinence (frequent urination)  Consequences -Obesity Pancreas: Obese people are at severe risk of Type-2 diabetes and insulin resistance Digestive canal: Obese people are more likely to develop cancer of the upper stomach, colon and rectum. Hands and legs: There is higher incidence of carpal tunnel syndrome in the wrists of the obese compared to other people. Obese people are also more prone to osteoarthritis of the knee, rheumatoid arthritis in the joints, deep vein thrombosis in the legs and Sever’s disease in the feet. Reproductive system: While obese men are more likely to suffer from erectile dysfunction, obese women are prone to irregular menstruation, cancer of the endometrial and pregnancy-related issues such as high BP, pre-eclampsia and gestational diabetes. Immune system: Obese people are more likely to develop infections and show delayed healing from wounds, burns and common ailments.  Components of Energy Expenditure Energy requirement - Amount of dietary energy needed to balance energy expenditure in order to maintain body size, body composition and level of necessary and desirable physical activity and also to allow optimal growth and development of children, deposition of tissues during pregnancy, and secretion of milk during lactation, consistent with long term goof health. For healthy, well nourished adults, it is equivalent to TEE.  Components of Energy Expenditure TEE –energy spent on average in a 24 hour period by an individual or a group of individuals. Energy needs vary widely among individuals in a group. Example 2 Example 1 Components of Energy Expenditure  Basal Metabolic Rate Basal Metabolism - comprises a series of functions that are essential for life such as cell function and replacement: The synthesis, secretion and metabolism of enzymes and hormones to transport proteins and other molecules; Maintenance of body temperature Involuntary work of cardiac and respiratory muscles Brain function BMR – Amount of energy used for basal metabolism in a period of time is called BASAL METABOLIC RATE.  Basal Metabolic Rate BMR - Measured under standard conditions that include Being awake in the supine position after 10 to 12 hours of fasting and eight hours of physical rest Being in a state of mental relaxation in an ambient env temperature Determined by age, gender, body size and composition Depending on age, lifestyle BMR represents 50 to 65 percent of the TEE.  Resting Metabolic Rate A closely related term to BMR is RMR (Resting Metabolic Rate). RMR – Measured with the subject in a supine/sitting position in a comfortable environment several hours after a meal and without any significant activity. RMR slightly higher than BMR. RMR when extrapolated to 24 hrs. is the REE  Thermic Effect of Food When a person eats, the GI tract muscles speed up their rhythmic contractions, the cells that manufacture and secrete digestive juices begin their tasks, and some nutrients are absorbed by active transport. This acceleration of activity requires energy and produces heat; it is known as the thermic effect of food (TEF). The metabolic response to food increases total energy expenditure by about 10% of BMR over a 24 hour period in individuals eating a mixed diet. TEF also known as “dietary induced thermogenesis “ and “Specific dynamic action food”.  Physical Activity Most variable and second largest component of energy expenditure. Physical activity –Obligatory and Discretionary Obligatory activities – imposed on the individual for economic, social and cultural demands. Discretionary activities – not socially, economically and culturally essential but are important for health, well being and good quality of life. E.g. Regular practice of physical activity for fitness, optional household tasks. During physical activity, the muscles need extra energy to move, and the heart and lungs need extra energy to deliver nutrients and oxygen and dispose of wastes. The amount of energy needed for any activity, whether playing tennis or studying for an exam, depends on three factors: muscle mass, body weight, and activity. The larger the muscle mass and the heavier the weight of the body part being moved, the more energy is expended.  Measurement of Energy Expenditure The standard unit for measuring energy is the calorie, which is the amount of heat energy required to raise the temperature of I ml of water at l5 degree C by 1 degree C. Because the amount of energy involved in the metabolism of food is fairly large, the kilocalorie (kcal or Cal) (1000 calories) is commonly used to measure it. A popular convention is to designate kilocalorie by Calorie (with a capital "C"). Various methods are available to measure human energy expenditure.  Direct Calorimetry Direct calorimetry monitors the amount of heat produced by a person placed inside a structure large enough to permit moderate amounts of activity. These structures are referred to as whole-room calorimeter. The method is limited by the confined nature of the testing conditions. Hence the measurement of TEE using this method is not representative of a free-living (i.e., engaged in normal daily activities) individual in a normal environment because physical activity within the chamber is limited. Its high cost and complex engineering and the scarcity of appropriate facilities around the world also limit the use of this method.  Direct Calorimetry - Principle Direct calorimetry monitors the amount of heat produced by a person placed inside a structure large enough to permit moderate amounts of activity. These structures are referred to as whole-room calorimeter. The method is limited by the confined nature of the testing conditions. Hence the measurement of TEE using this method is not representative of a free-living (i.e., engaged in normal daily activities) individual in a normal environment because physical activity within the chamber is limited. Its high cost and complex engineering and the scarcity of appropriate facilities around the world also limit the use of this method. Direct Calorimetry  Indirect Calorimetry - Principle Measures the amount of oxygen consumed and carbon dioxide produced during respiration. These values are used to estimate energy expenditure since oxygen is required for the oxidation of carbohydrates, fats, and proteins, which release energy.  Indirect Calorimetry - Procedure The subject breathes into a mouthpiece or mask connected to a gas analysis system. The system measures the volume and composition of the expired gases, particularly the oxygen consumed (VO₂) and the carbon dioxide produced (VCO₂). Using known conversion factors, oxygen consumption is used to calculate energy expenditure. The Respiratory Quotient (RQ), which is the ratio of CO₂ produced to O₂ consumed, helps determine which macronutrients (carbohydrates, fats, proteins) are being oxidized. The calculation of energy expenditure is based on the assumption that the oxidation of different macronutrients requires a specific amount of oxygen and releases a defined amount of energy.  Indirect Calorimetry - Procedure Data are obtained from indirect calorimetry in a form that permits calculation of the respiratory quotient (RQ): RQ : Moles CO2 expired /Moles 02 consumed The RQ depends on the fuel mixture being metabolized. The RQ for carbohydrate is 1 because the number of carbon dioxide molecules produced is equal to the number of oxygen molecules consumed. RQ : 1 for carbohydrate, 0.85 for a mixed diet, 0.82 for protein, and 0.7 for fat  References https://www.fao.org/4/y5686e/y5686e04.htm Roday, S. (2018). Food science and nutrition. Oxford University Press. Mahan, L. K., & Escott-Stump, S. (Eds.). (2012). Krause's food, nutrition, and diet therapy (13th ed.). Elsevier/Saunders. Srilakshmi, B. (2018). Nutrition science (7th ed.). New Age International Publishers.