Energy Balance +Notes PDF

Energy Balance Energy balance: the energy (kcalories) consumed from foods and beverages compared with the energy expended through metabolic processes and physical activities. What is the opposite of energy balance? 4  Energy...

Energy Balance Energy balance: the energy (kcalories) consumed from foods and beverages compared with the energy expended through metabolic processes and physical activities. What is the opposite of energy balance? 4  Energy Balance Excess energy stored as fat - Fat used for energy between meals Classic rule: - Adipose tissue: 87% fat - 1 pound of fat = 3500 kcalories Limitations: - Differs with gender and weight 5  Energy Imbalance Deficiency of energy intake – Symptoms of undernutrition: becoming extremely thin, losing muscle tissue, and becoming prone to infection and disease. Excess of energy – Obesity and vulnerability to diseases associated with overnutrition (heart disease and diabetes). Deficiency of a nutrient – Skin rashes, depression, hair loss, bleeding gums, muscle spasms, night blindness, or other symptoms. 7  Energy Imbalance What happens when a person doesn’t get enough or gets too much of a nutrient or energy? If the deficiency or excess is significant over time, the person exhibits signs of malnutrition. 8  Malnutrition Malnutrition: any condition caused by excess or deficient food energy or nutrient intake or by an imbalance of nutrients.  Undernutrition: deficient energy or nutrients  Overnutrition: excess energy or nutrients 9  Energy In: The kCalories Foods Provide Direct measure of food’s energy value: - Bomb calorimeter Indirect measure of energy released: - Oxygen consumed kCalorie calculations - Physiological fuel value: the number of kcalories that the body derives from a food, in contrast to the number of kcalories determined by calorimetry 10  Food intake Appetite: the integrated response to the sight, smell, thought, or taste of food that initiates or delays eating Hunger: the painful sensation caused by a lack of food that initiates food-seeking behavior Factors that influence hunger: Presence or absence of nutrients in the bloodstream. Size and composition of the preceding meal. Customary eating patterns, climate(heat reduces food intake; cold increases it). Physical activity Hormones Illnesses. 12  Food intake Hypothalamus: a brain center that controls activities such as maintenance of water balance, regulation of body temperature, and control of appetite. Satiation: the feeling of satisfaction and fullness that occurs during a meal and halts eating. – Satiation determines how much food is consumed during a meal. Satiety: the feeling of fullness and satisfaction that occurs after a meal and inhibits eating until the next meal. – Satiety determines how much time passes between meals 13 15  Factors That Influence Eating Overriding hunger and satiety – Eating can be triggered by signals other than hunger, boredom, anxiety, stress. External cues – Time of day, availability, sight, and taste. Environmental influences – Large portion sizes, favorite foods, abundance or variety of foods. Cognitive influences Disordered eating – Signals other than satiety that suppress eating, e.g Anorexia nervosa 16  Nutrient Composition for Sustained Satiation and Satiety Protein is most satiating – provides feelings of fullness and satiety Fructose in a sugary fruit drinks may stimulate appetite and increase food intake Low-energy density – High-fiber foods & – More satiating High-fat foods – Strong satiety signals  Cholecystokinin: signals satiety and inhibits food intake. – Little satiation during a meal  May lead to overconsumption 17  Energy out Thermogenesis: the generation of heat – Used in physiology and nutrition studies as an index of how much energy the body is expending – The total energy a body expends reflects three main categories of thermogenesis: Energy expended for basal metabolism Energy expended for physical activity Energy expended for food consumption 19 20  Basal Metabolism Basal metabolism – the energy needed to maintain life when a body is at complete digestive, physical, and emotional rest – 2/3 of daily energy expended Lungs inhaling and exhaling air, the bone marrow making new RBCs, the heart beating 100,000 times a day, and the kidneys filtering wastes... Basal metabolic rate (BMR) – the rate of energy used for metabolism under specified conditions: after a 12-hour fast and restful sleep, without any physical activity or emotional excitement, and in a comfortable setting Usually expressed as kcal/kg of BWt/hr 21  Basal Metabolism Resting metabolic rate (RMR) – a measure of energy use for a person at rest in a comfortable setting, but with less stringent criteria for recent food intake and physical activity RMR is easier to determine, but slightly higher than the BMR 22 23  Physical Activity Physical Activity: Voluntary movement of the skeletal muscles and support systems – most variable and the most changeable component of energy expenditure – Amount of energy expended depends on: 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 See Table 8.3 Page 238 Notes :Estimating Energy Expended on Physical Activities 25  Thermic Effect of Food (TEF) Thermic Effect of Food (TEF): An estimation of the energy required to process food – digest, absorb, transport, metabolize, and store ingested nutrients – also called the specific dynamic effect (SDE) of food or the specific dynamic activity (SDA) of food – usually estimated at 10% of energy intake – TEF is greater for high-protein foods than for high- fat foods – TEF is greater for a meal eaten all at once rather than spread out over a couple of hours – See Table 8.4 Page 238 26  Recap List and explain the three main components of energy expenditure by the body? 27  Estimating Energy Requirements Equations developed by the DRI Committee – Gender women have lower energy requirements than men – Growth Energy needs are high in people who are growing – pregnant and lactating women, infants, children, and adolescents – Age Energy needs decline during adulthood – Physical activity Physical activity factor – activities are clustered according to the typical intensity of a day’s efforts 29 Estimating Energy Requirements Equations developed by the DRI Committee – Body composition and body size Height and weight factors Q: What do you see in the picture? 30  Body Composition Body Composition: The proportions of muscle, bone, fat, and other tissue that make up a person’s total body weight – Body weight = fat + lean tissue (including water) Defining Healthy Body Weight – The Criterion of Fashion – Body image – The Criterion of Health 32  Body Mass Index (BMI) Measure of relative weight for height – BMI = weight (kg) / (height (m))2 Does not assess body composition Overweight vs overfat – Muscular athletes – See Page 243 34  Body Fat and Its Distribution Important information for disease risk – How much of weight is fat? – Where is fat located? Visceral fat, stored around the organs of the abdomen – Central obesity or upper-body fat  contributes to heart disease, cancers, diabetes, and related deaths Subcutaneous fat, stored directly under the skin Lower body fat around the hips and thighs is most common in women during their reproductive years  associated with fewer heart disease risks 35 “Apple” & “Pear” Body Shapes Compared 36 “Apple” & “Pear” Body Shapes Compared 38  Waist Circumference A waist circumference of >40 inches for men, and >35 for women is an indicator of fat distribution and central obesity. Waist circumference together with BMI are inexpensive, easy to obtain, and valuable in assessing a person’s health risk Waist circumference alone is the preferred method for assessing central obesity. 39 Common Methods Used to Assess Body Fat 40  Health Risks Associated with Body Weight and Body Fat Body weight and fat distribution correlate with disease risk and life expectancy – Correlations are not causes – diabetes, hypertension, cardiovascular disease, sleep apnea, osteoarthritis, some cancers, gallbladder disease, kidney stones, respiratory problems. Risks associated with being underweight – Fighting against wasting diseases – Menstrual irregularities and infertility – Osteoporosis and bone fractures 41 BMI and Mortality 42  Risks Associated With Being Overweight & Obese Obesity is a designated disease – Health risks More likely to be disabled in later years Costs – Medical costs – Lost productivity – Premature death 43  Specific Disease Risks Cardiovascular disease – Blood cholesterol and hypertension – Central obesity  Benefits of weight loss Diabetes— type II – Central obesity – Weight gains and body weight Cancer – Time and degree of overweight/obesity 44  Inflammation and the Metabolic Syndrome Chronic inflammation – Weight gain and location of stored fat  Ectopic fat and insulin resistance  Gene expression → increased inflammation – Cluster of symptoms increases risk for other chronic diseases Other considerations – Fitness at different BMIs  Healthy obese  Limitations of BMI 45