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Overweight and Obesity (week 11).docx

19 Pages

Health Studies
Course Code
HLTH 230
Jeffery Lalonde

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Over Weight and Obesity 12/24/2012 6:43:00 AM Overweight and Obesity  Energy Balance o When energy in is equal to energy out, a person’s body weight is stable o When energy in is greater than energy out, body weight increases o When energy in is less than energy out, body weight decreases  Excess protein, excess carbohydrates, excess fat, and excess alcohol can lead to increased body fat o Energy goes up and down throughout the day Macronutrient Broken into Carbohydrate Glucose Stored: Glycogen stores Body fat stores Fat Fatty Acids Stored: Body fat stores Protein Amino Acids Stored: Body fat stores Individuals are constantly burning energy, even at rest  Basal metabolic rate We eat to refuel  When the energy we refuel does not equal the energy expended, weight will change o If food intake is 3500 kcal greater than expenditure, we will gain 1 pound of fat  3500kcal = 1 lb gain  Healthy weight adult has energy stores between 50,000 and 200,000 kcal o Only 1500-200 kcal from glycogen, in liver and muscle  If calories are less, regardless of what you eat, you will lose weight o 1 kcal = 4.184 joules o Energy needed to burn 1 kcal o Energy that increases 1g of water by 1 degree  A fast change in body weight is not a change in body fat o Lose 1 litre of water, lose 2 pounds o Glycogen is hydrophilic, holds on to water  Change in the amount of fluid in the body is responsible for rapid weight change Weight loss  Long term weight loss is generally 75% fat and 25% lean tissue o Gradual and slow weight loss o Slight caloric deficit  Starvation / Rapid weight loss o 50% fat and 50% lean tissue o Severe caloric deficit  Fat losses and gains should be gradual Rapid weight loss – yoyo effect  Starved volunteers for 24 days o Loss mass and fat  After refeeding for 12 days eating whatever they want o When they reached 100% normal weight they entered hyperphagia  Eating more than normal  Fat mass and fat free mass after weight loss influences how much a person is going to eat o Put on more weight than initial weight after starvation Basic Chemistry – Energy in  Food and drink provide energy  Calorie content of foods o Burning foods  When food is burned the chemical bonds between carbon and hydrogen break  Releases energy in the form of heat  Measure the amount of heat, will tell you how many calories  Problem  Overstates the amount of energy human body gets from foods  Human body is not that efficient  We do not use all of those calories  Overestimates how many calories are actually used  Indirect calorimetry o Carbon dioxide and water are produced  The amount of oxygen used givens indirect measure of heat produced  Energy of foods can also be calculated by calculating fat, carbohydrate, protein, and alcohol in food o Fat as most energy = 9 kcal o Alcohol has 7 kcal o Carbohydrates and protein have 4 kcal of energy Food Intake Regulation  Appetite o Integrates response to the sight, smell, thought, or taste of food that initiates or delays eating  Can be experienced without hunger  Prompts a person to eat or not eat  Eg. Favourite dessert after a big meal  Sigh and smell triggers appetite, not hunger o You can also be hungry, but no appetite  Eg worried, tired, sick  Hunger o Irritating painful sensation caused by a lack of food o Initiates food seeking behaviour o Triggered by chemical messengers initiating in the brain  Hypothalamus  When you eat, it takes times for nerves in the upper digestive tract to signal the hunger centre in the hypothalamus to turn off o Can be influenced by:  Presence or absence of nutrients in the blood  Size and composition of preceding meal  Whether GI tract has emptied  Climate  Cold increases intake  Heat decreases intake  Customary eating patterns  Routines, other people, holidays  Exercise  Increased need for macronutrients  Hormones  Anorectic hormone (ANOREXIA – WANT WEIGHT LOSS, NOT HUNGRY)  Suppresses appetitive  Promotes weight loss  Promotes negative energy  Orexigenic Hormone  Increasing hunger  Increasing intake  Illness o The stomach is a reservoir which handles periodic amounts of food  Most food has left the stomach after 4 hours  Most people do not feel like eating again until the stomach is empty  Satiation DURING o The feeling of satisfaction and fullness that occurs DURING a meal, halts eating  Determines how much food is consumed at a meal  Receptors in the stomach stretch and the person begins to feel full  Satiation occurs and the person stops eating  Satiety AFTER o The feeling of satisfaction that occurs AFTER a meal o Inhibits eating until next mean  Satiety determines how much time passes between meals  Satiation tells us to stop eating  Satiety tells us not to start eating again  Satiety can be overridden by appetite  Favourite food can cause you to keep eating  Regardless of hunger, people typically over eat when offered an abundance and variety at buffets  Sensory Specific Satiety o We tend to get bored of food as we eat it o The more variety there is, the more likely it will increase over all consumption  Buffet o Pleasantness of food decreases  Satiety can be specific to food  Overriding hunger and satiety o Food cravings when bored o Eat when celebrating o Eat when stressed o Eat more with variety and large portions o Discipline can lead us to ignore hunger o Not eating when excited  Portion size o People tend to eat more when portions are larger  Increase in obesity due to increase in portion sizes  Influences energy intake  Despite increases in intake, those who consume large portions do not report to increased levels of fullness  Eating low energy dense foods (fruits, vegs) maintains satiety while reducing energy intake  Bottomless bowl o People eat more when they think there is more food o Judgment of calories becomes false  Despite addition of food, people did not feel more full Sustaining satiation and satiety  Ability of food to produce satiation and sustain satiety depends on nutrient composition o Protein is the most satiating energy yielding nutrient o Food rich in fibre provides satiation by filling the stomach and delaying gastric emptying  Prolonging satiety o Fructose in sugary fruit drinks may stimulate appetite and increase intake  Fat has a week effect on satiation o High fat foods are flavourful  Increases appetite  Energy dense o Fat provides little satiation during, o Strong satiety after a meal once it reaches intestines  Fat in the intestines triggers release of CCK  Signals satiety o High fat foods must be eaten in small portions compared to fibre fich foods  Portion size correlates with food satiety Hypothalamus  Control centure, message centre o Integrates messages about energy intake o Expenditure and storage from other parts of the brain, mouth, liver, GI tract  Chemicals in the brain participate in appetite control and energy balance o Neuropeptide Y  Favours positive energy balance  Orexigenic  Initiates eating  Causes carb cravings  Decreases energy expended  Increases fat storage o Gastrointenstinal Hormones that regulate food intake  Amylin  CCK  Pancreatic peptide  Etc Energy Out  Breaking down energy yielding nutrients involves work and produced heat o Thermogenesis  Total body energy expenditure o Basal metabolism o Physical activity o Food consumption o Climate  Eg stress, trauma Basal Metabolic Rate  2/3 of the energy expended by an average person per day  Metabolic activities include o Maintaining body temperature o Breathing o Circulation o Making red blood cells, tissues  The rate at which the body expends energy to maintain vital functions when they body is at digestive, physical, and emotional rest o In general, the more a person weights, the greater energy is needed on basal metabolism o The energy expended per pound may be lower  Eg 150 pound adult has a higher metabolic rate than a baby  But the baby has a higher metabolic rate  Growing  Basal metabolic rate is higher in o People who are growing (children, pregnancy) o People with more lean muscle mass  Active tissue o During stress o Hyperthyroidism o Caffeine o Smoking o Environmental temperatures  Body has to do more work  BMR slows down with o Fasting  Body attempts to converse fuel stored o Malnutrition o Age  Declines with age  Sacropenia  Muscle loss due to age  BMR o Rate of energy use for metabolism under specific conditions  After 12 rest  Without physical activity or emotional excitement  Comfortable setting  Resting Metabolic Rate o A measure of energy use of a person at rest in a comfortable setting o Less strict criteria for food intake and physical activity  RMR is usually higher than BMR because it is less prepared for strict conditions Physical Activity  The voluntary movement of the skeletal muscles and support systems  Most variable and changeable component of energy expenditure  Extra energy is required to the move  The heart and lungs require extra energy  How much energy is required will depend on o The persons weight o Muscle mass o The activity being performed  Intensity and duration Thermic Effect of Food  10% of intake  When a person eats, GI tract muscles speed up their activity o Increased energy produces heat o Thermic effect of food  Thermic effect of food is higher for a meal eaten all at once than spread out over a couple of hours o Generally TEF is not counted  No research for negative calorie foods  TEF o Fat 0-5% o Carbohydrate 5-10% o Protein 20-30% o Alcohol 15-20% Adaptive Thermogenesis  Additional energy expenditure when the body is dramatically challenged o Physically conditioning o Extreme cold o Overfeeding o Starvation o Trauma  Body has extra work to do  Uses extra energy to build tissues, making hormones, etc. Alcohol and Appetite  Alcohol (ethanol) has 7kcal  Can decrease lipid oxidation by 70% o Less lipids being broken down  Body usually compensates by decreasing appetite because lipids are not being broken down and enough calories are consumed o Not the case for alcohol  Alcohol can stimulate appetite o Decrease in leptin levels Obesity a
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