Today s Topics. Energy Balance. Energy Balance. Energy Balance and Weight Management: Finding Your Equilibrium 9/8/15

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1 Today s Topics Energy Balance and Weight Management: Finding Your Equilibrium BIOL 103, Chapter 8 Energy In Energy Out Body ComposiJon: Understanding Fatness and Weight Overweight and Obesity Weight management Underweight Energy Balance Energy Intake vs. Energy Output Energy equilibrium Intake = output weight PosiJve energy balance Intake Output Gain weight NegaJve energy balance Intake Output Lose weight Energy Balance 1

2 Energy In Key concept: Food intake is regulated by sensajons of 1. Hunger: a physiological drive to eat 2. Sa3a3on: feelings of sajsfacjon that lead to ending a meal 3. Sa3ety: conjnued feelings of fullness that delay that start of the next meal 4. Appe3te: the psychological urge to eat and oxen as no relajon to. Internal Cues that Regulate Energy Intake QuesJon: Are your internal cues regulated by physiological drive or psychological drive? Why does our stomach growl? Stomach growling can happen any Jme, but with food, it becomes quieter. Empty stomach à stomach produce hormones that sjmulate local nerves to send a message to the brain à brain signals digesjve muscles to restart the process of peristalsis à contracjons occur to sweep up any remaining food AND vibrajons in your stomach occur to make you feel hungry. What sjmulates our internal/external cues? Control by commi_ee What factors sjmulates our cues? 1. Internal: Examples: in our GI tract, central nervous system, general circulajon 2. External: Examples: where we are eajng, what we are eajng, who we are eajng with 2

3 Internal Factors 1. GastrointesJnal sensajons Sense of fullness as the ingested food stretches your stomach/intesjne Ex: sushi and water 2. Neurological and hormonal factors Neuropep3de Y NeuropepJde Y acjvity can be affected by signals from ghrelin and lepjn à affects daily feeding pa_ern Ghrelin: hormone from stomach Lep3n: hormone by adipose cells External Factors that affect your Energy Intake 1. Diet composijon Energy density (kcal/g of food) Balance of energy sources (carbs, fat, proteins) Form (liquid vs. solid) 2. Sensory properjes Taste, texture, color, temperature, presentajon External Factors Energy In: Regulatory Factors 3. PorJon size Super- size culture, McDonald s value meals never ending bowl of soup 4. Environmental and social factors Eat more in cold weather, eat less in hot weather Why? Hypothalamus More people in the group 5. EmoJonal factors EaJng to cope with stress, low self- esteem, boredom, low energy levels 3

4 How does our bodies use energy? 1. Res3ng energy expenditure or (REE) 2. Thermic effect of food (TEF) 3. Physical ac3vity (PA) REE + TEF + PA = Total Energy Expenditure Energy Out: Fuel Uses Major components of Energy Expenditure: 1. Res3ng Energy Expenditure (REE) Energy for basic body funcjons Affected by body size, composijon, age, and gender 2. Physical Ac3vity (PA) Highly variable Affected by body size, fitness level, and type of acjvity 3. Thermic Effect of Food (TEF) Energy to digest, absorb, metabolize food How to Calculate your TEE EsJmaJng total energy expenditure: Res3ng energy expenditure (REE) Males: 1.0 kcal/kg/hr Females: 0.9 kcal/kg/hr REE = weight (kg) x [ kcal/kg] x 24hr/day Physical ac3vity EsJmated by how much an individual with a certain amount of body weight exercised in a given Jme Refer to Table 8.2 Thermic effect of food 0.1 x (REE + physical acjvity) EsJmaJng Energy Expenditure Just as there are DRIs for nutrients, there are also DRIs for energy, called Es3mated Energy Requirement (EER) DefiniJon: energy intake predicted to maintain energy balance in a healthy person of normal weight EquaJons for males and females Factors for age, weight, height, and physical acjvity Predicts total energy expenditure (TEE) See Table 8.4 for more details 4

5 Body ComposiJon: Understanding Fatness and Weight Body composijon Is the rela<ve amount of fat and lean muscle mass Muscle is than fat Assessing body weight Body mass index (BMI) = Weight (lb) x Height 2 (in) BMI 18.5 kg/m 2 = underweight BMI 18.5 to 25 kg/m 2 = normal weight BMI 25 to 30kg/m 2 = overweight BMI 30 kg/m 2 = obese Q: Does BMI indicate how much fat you have? Problem Set 8, QuesJon 3 BMI = x [weight (lb)/height (in 2 )] REE for women = (weight in kg) x 0.9 x 24 REE for men = (weight in kg) x 1.0 x 24 TEF = 0.1 x (energy from physical acjvity + REE) TEE = REE + energy from physical acjvity + TEF How to measure body fatness? Can do this because fat and lean Jssues have different densi<es 1. DXA: Dual Energy X- ray Absorp3ometry 2. Underwater weighing Q: If 2 people with the same weight but different levels of fat were weighed in water, who would weigh less? 3. BodPod 4. Skinfold measurements 5. Bioelectrical impedance Overweight and Obesity Overweight/Obesity is a major public health problem A global problem US: of American adults are overweight/ obese Affects adults and youth Healthy People 2020 goal: to reduce (by 10%) the proporjon of adults, adolescents, and children who are obese 5

6 Factors in Development of Obesity 1. Biological: 1. GeneJc/heredity 2. Race and Ethnicity 3. Fat cell development: number and size of fat cells help determine how easily a person gains or loses fat. Hypertrophic obesity Hyperplas3c obesity HyperplasJc vs. Hypertrophic 1. Biological, conjnued 4. Sex and Age As children: boys are less likely than girls to consider themselves overweight As adults Men: men see themselves as overweight at higher weights Women: women see themselves as overweight at healthy weight Men/Women tend to gain most weight between years of age Factors in Development of Obesity 2. Social and environmental 1. Socioeconomic status 2. Built environment 3. Social factors 3. Lifestyle and behavior 1. Physical acjvity (ex: lack of exercise) 2. Psychological factors (ex: restrained eaters, binge eaters) Overweight and Obesity Health risks of overweight and obesity Weight cycling or yo- yo diejng Associated with negajve effects on health risks, body composijon, body fat distribujon, and energy expenditure. Prone to future weight gain 6

7 Weight Management Weight management is the adopjon of healthful and sustainable ea<ng and exercise behaviors indicated for reduced disease risk and improved feelings of energy and well- being. Weight Management The percepjon of weight 1960s: thin was in MulJple factors contribute to obesity: genejc, psychological, metabolic, hormonal, environmental, behavioral, sociocultural Health professionals emphasize and f Weight Management The PercepJon of Weight What goals should I set? 1. Set realisjc and a_ainable goals 2. Aim for metabolic fitness than a specific weight Metabolic fitness: the absence of all metabolic and biochemical risk factors associated with obesity 7

8 Diet and EaJng Habits Total calories Limiting portion sizes or reducing total calories intake Crash diets don t work Highly restrictive diet = not long-term Starving a meal can actually make you hungrier à eat more! Diet and EaJng Habits Balancing energy sources: fat, carbs, and protein Fat: 20-25% of total calories Eat healthy sources of fat (PUFA) and fiber to delay satiation Carbs: 45-65% of total calories Low sugar foods (ex: fresh fruits) Protein: 10-35% of total calories Eating habits Regular Physical Activity Thinking and EmoJons Balancing Acceptance and Change IniJal weight loss: loss Weight loss then can slow down to a plateau of lb/week IniJal loss = fluid loss Later loss = fat loss Weight Management Approaches 1. Self- help books Watch out for signs of a fat diet Warnings: quick and easy, scienjfic breakthrough 2. Meal replacements Slim- fast diet 3. Self- help groups Help cope with weight 8

9 Weight Management Approaches 4. Commercial programs 1970s: Very- low calorie diet 5. Professional counselors 6. FDA- approved weight- loss medicajons AppeJte suppressants Lipase inhibitor Effect is modest; sjll encourage exercise + low fat food. Weight Management Approaches 7. Over- the- counter drugs and dietary supplements Does not need FDA approval before markejng Pills of caffeine, fiber (dehydrajon), benzocaine (numbs tongue to reduce taste sensajons) 8. Surgery (BMI >40) Last- ditch effort Gastric banding (stomach stapling) Gastric bypass Gastric Bypass + Banding Weight Management Approaches Surgery, cont. Liposuc3on: not highly effecjve because body sjll has visceral fat, ready to store extra fat Risks: blood clots, perforajon injuries, skin, nerve damage, etc. Surgery should be complemented with exercise and a healthy diet. Maintaining healthy ea<ng habits is very important! 9

10 Underweight Causes and Assessment Altered responses EaJng disorders factors Metabolic and heredity factors Prolonged physical and emojonal stress AddicJon to alcohol and street drugs Bizarre diet pa_erns Underweight Weight gain strategies: 1. Small, frequent meals 2. Fluids between meals 3. High- calorie foods and beverages 4. Timers or other cues similar to ABC model 5. Vitamin/mineral supplements 10