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Biology 45 – Weight ControlAnna Miller, MS, RD 1Biology 45What you weigh is related to how many calories you eat relative to how many you expend. One pound of fat contains approximately 3500 calories.Energy Balance Matters!Energy BalanceBiology 45Questions!• If a person ate 100 calories over “energy balance” every single day for a year, how much weight would this person gain in a year?• If a person was in “negative energy balance” by 500 calories everyday for a week, how much weight would this person lose in this week?• Can a person gain 5 pounds of fat in a single day of overindulging (like on Thanksgiving)? If so, about how many calories would you have to eat?Biology 45“Energy In” and the Hypothalamus • The brain turns on/off: Hunger Satiation Satiety• Why does the brain turn on hunger? • How does it know when to on satiety?Biology 45 – Weight ControlAnna Miller, MS, RD 2Biology 45“Internal Cues” of Food Intake• Nerve signals from stomach• Hormones Digestive Leptin Ghrelin, PYY• Brain chemicals Serotonin Neuropeptide Y Others• More……Biology 45Question!• Does your knowledge that you ate influence hunger/satiety?Biology 45Questions!• What is “appetite”? How is it similar to hunger? How is it different? • Can appetite override satiety? • Can lack of appetite override hunger?Biology 45 – Weight ControlAnna Miller, MS, RD 3Biology 45“External Cues” • The Sight or Smell of food• Social eating• Emotions  Eating when you’re: Sad Bored Frustrated Angry  Happy Stressed MoreBiology 45Questions!• Why do we eat when in response to emotions, especially when we’re not at all hungry?• Is “comfort eating” biological or learned?Biology 45Do You Eat…Mindfully….or….Mindlessly?Mindful eating is eating while paying attention to your hunger/satiety signals, to the way the food tastes, the textures, the sensations…..all without judgment!Try it! It’s Very Empowering!Biology 45 – Weight ControlAnna Miller, MS, RD 4Biology 45Components of “Energy Out” Biology 45Basal Metabolism• The minimum amount of energy needed to maintain life. Basal metabolic rate (BMR) What kind of functions in the body use energy that falls under this category? How many calories are used for basal metabolism? What kind of factors influence BMR?Biology 45Components of “Energy Out”• Physical activity Exercise General movementBiology 45 – Weight ControlAnna Miller, MS, RD 5Biology 45Components of “Energy Out”• Thermic Effect of Food (TEF) Energy expended to digest, absorb food and transport nutrients ~10% of energy intake Varies depends on food eatenBiology 45• Estimate “energy out” (+/- 200-400 calories) Start with a BMR equation• Based on gender, age, weight• Not all factors that influence BMR are taken into account! Add factor for activity Example in your text; charts in Appendix F Google “caloric need”. These sites plug your info into equations. Do several. You will need to estimate your caloric need for part 3 of your assignment! Why?How Many Calories Do I Need?Biology 45Body Mass Index (BMI)= weight (kg)height (m)2wt in kg = wt in lb/2.2ht in m = ht in inches/39Calculate YOUR BMI!A guideline for assessing your body weight, or for determining a “Healthy Weight” rangeBiology 45 – Weight ControlAnna Miller, MS, RD 6Biology 45Biology 45Questions!• In what way might the BMI not be an accurate assessment of a person’s weight? For whom?• Do we disregard the BMI because of its limitations?• What other tools can be used, when necessary?Biology 45Biology 45 – Weight ControlAnna Miller, MS, RD 7Biology 45Methods Used to Assess Body FatBiology 45Where is Your Fat?• A lot of belly fat (the Omentum) is associated with more:• Heart disease• Stroke• Hypertension• Diabetes/metabolic syndrome• Some cancersBiology 45An Important Number• Your Waist Circumference!• Measure correctly• Ideal (health-wise): waist no greater than half your height• Maybe a better predictor of health risk than BMIBiology 45 – Weight ControlAnna Miller, MS, RD 8Biology 45Health Risks • Diabetes/Metabolic Syndrome• CVD• Hypertension• Some types of cancer• Sleep Apnea• Arthritis• And more…. PLUS, a Sedentary Lifestyle increases risk even more!Biology 45• But…..Obese people can be healthy!• Fat and fit versus sedentary and slim• Future nurses: don’t assume your obese patients are unhealthyBiology 45Fat Cell Metabolism Enzyme Review• LPL promotes fat storage Estrogen, pregnancy, starving, dieting, weight loss ’s LPL activity• HSL pulls fat out of storage, to be burned Exercise ’s its activity Dieting and fasting  itBiology 45 – Weight ControlAnna Miller, MS, RD 9Biology 45“Obesity is not a sin. At most it is… the result of not having kept up the lifelong battle against an inherited predisposition and against an environment which combines constant exposure to food with the removal of any need to work for it physically”Dr. Jean Mayer 1968Biology 45Genetics• Genetic mutation as cause of obesity exists but is very rare• Genetic predisposition is probably common How might our genes/our biology influence our body weight (fat)?Biology 45Leptin• Hormone produced by fat cells. More fat on the body, more leptin• Leptin turns on satiety (has other roles too)• Ob gene codes for leptin• If there is a mutation in this gene and you don’t make leptin, you would not feel satiety normally. Is this the cause of obesity? •In mice yes, but not in humans• Leptin insensitivity?•Influenced by diet and lifestyle?Biology 45 – Weight ControlAnna Miller, MS, RD 10Biology 45Effects of LeptinWithout leptin, this mouse weighs almost three times as much as a normal mouse.With leptin treatment, this mouse lost a significant amount of weight but still weighs almost one and a half times as much as a normal mouse.Biology 45Other Hormones• Ghrelin Produced by the stomach Goes to hypothalamus, turns on hunger (plus other roles) Levels vary in different people• PYY (Peptide YY) Produced by the small intestine in the post absorptive state Causes ghrelin to decline; Turns on satiety• Many othersBiology 45Not Enough Sleep and Weight Gain• Studies have shown that lack of sleep may lead to  Increased ghrelin Decreased leptin• These will have


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De Anza BIOL 45 - Weight Control

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