Energy Balance and Body Composition Chapter 8 Fasting Feasting Review Too little energy in the diet Fat used for energy lean tissue used to meet glucose and protein needs trend is towards losing weight either in fat or lean tissue Too much energy from food is stored as fat Fat used for energy between meals famine Weight gain Energy Balance Energy balance energy kcal Energy balance is energy in energy out Energy balance energy kcal consumed from foods and beverages compared with the energy expended through metabolic processes and activities Energy balance energy in energy out A shift in balance causes weight changes Not simply fat changes proteins attract water lose protein and glycogen lose weight Carb loading will gain weight then lose again as mostly water after the race of muscle because need glucose and amino acids 1 pound of fat 3500 kCalories in time of need long term deficit of 3500 calories lose a Water 60 of body wt retention or loss Long term 75 fat 25 lean safest and longest lasting Starvation 50 fat 50 lean breakdown of protein is happening shift towards more pound of fat measure heat as energy Measuring energy released from food Direct Calorimetry bomb calorimeter direct measurement of what the food provides exact Indirect Calorimetry end products are co2 and h2o addition of oxygen to products and then as exhale can measure how much of that oxygen was consumed how much we used not what the food provided kCalorie calculations Food Composition Physiological fuel value what we get from the good vs what it gave the number of kCals that the body derives from a food not the number of kcal provided by a food as determined measure oxygen consumption by face mask or canopy hood Still only an estimate not exact from bomb calorimetry we don t get 100 of our energy from out food we use some for metabolism Differs from measurements of food composition Can correct with mathematical formulas to provide tables 8 1 and 8 2 Review What is physiological fuel value How much energy of kCals we get from food Three different methods and instruments if applicable that can be used to determine the energy provided by food or food composition are 1 Direct Calorimetry bomb calorimeter 2 3 kCalorie calculations Indirect Calorimetry face mask or canopy hood Describe the accuracy and or variability of these methods all an ESTIMATE Can not be exact Energy In Food Intake Appetite integrated response to sight smell thought or taste of food that initiates or delays eating feeling want Hunger sensation caused by a lack of food that initiates food seeking behavior physiological response Physiological response to nerve signals and chemical messengers originating and acting in brain Hypothalamus acting here brain s center for food Influences on hunger Presence or absence of nutrients in bloodstream Size and composition of preceding meal Customary eating patterns Climate heat cold Physical Activity Hormones insulin and glucagon Illnesses i e stomach virus Satiation what signals that we stop eating determines amount in meal During meal food enters GI satiation occurs Receptors in stomach stretch Hormones i e Cholecystokinin CCK active Begin feeling full and prompted might override this to stop eating Satiety not to start eating again determines time between meals 4 hours after a meal most or all of food leaves stomach emptiness of stomach influences hunger satiety Influencing satiation and satiety Nutrient composition Studies that show Eating salad before meal can reduce total kcal intake high Protein is most satiating vs fructose Low energy density satiating because of volume fills up the stomach High fiber foods satiating by filling stomach stretch receptors fiber low energy density satiation signal really level fat travels slower so more time before feel hungry High fat foods Weak satiation signal can passively overeat easier because can t sense the Strong satiety feel fuller longer signals triggers CCK release less scientific The hypothalamus all together and gives us that feeling Control center for eating Integrates messages about energy intake expenditure storage of fat of glucose from mouth GI tract and liver messages from here hypothalamus puts that Amylin Cholecystokinin activated because slows the movement of food through the Gastrointestinal hormones that regulate food intake digestion tract when fat enters the intestine Enterostatin Ghrelin Glucagon like peptide 1 GLP 1 Oxyntomodulin Pancreatic Polypeptide PP Peptide YY PYY Neuropeptide Y causes CHO cravings initiates eating energy expenditure fat storage these factors support positive energy balance and weight gain what can we do to suppress it 8 2 Energy In Review Appetite is a feeling craving desire to eat Perception Hunger is a physiological reaction sensation need signal to eat Satiation is the signal that the body sends for the person to stop eating because the body is Satiety is how long your fullness can last how long you re told you have enough reminder to full not start eating again Emotional Environmental Cognitive Disordered eating Overriding hunger satiation and satiety Examples illness tastes good stress too stressed to eat so stressed all I want to do is eat social cues body image abundance of food buffet medication emotions climate smell good bad memories perceptions Review Energy In Food Intake What is the hypothalamus Describe the action of 2 of the hormones involved in hunger cholecystokinin and Food control center in the brain Cholecystokinin slows down food movement in GI tract when fat is present in the neuropeptide Y intestine support positive energy balance and weight gain Neuropeptide Y Makes people crave carbs initiates eating increases fat storage Adaptation Basal metabolism Physical activity Food consumption Energy Out Thermogenesis generation of heat used as index of how much energy body is expending 3 main categories 4th category sometimes not always involved Energy Out Basal Metabolism Uses about two thirds of the energy expended in a day It s for the metabolic activities all the basic activities of life activities supporting these basic activities intake not as strict Can use instruments to measure basal metabolic rate Resting metabolic rate RMR usually higher testing criteria physical activity food Varies across people and for same person different ages in your life Weight Lean tissue lean tissue amount All basic processes of life Basal metabolic rate BMR rate at which body expends energy for life sustaining
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