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Lecture 9

Lecture Nine - Eating & Hunger

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Mandy Wintink

Lecture 9: Eating & Hunger March 17, 2014 5:18 PM • "Preparing for hibernation mode" o Harvest, etc. Eating Behaviors • Paleo Diet o Low carb - Atkin diet o Mimics Paleolithic lifestyle; lots of fish, grass fed meat, root vegetables (but removes the greens); predominantly meat • Vegetarian • Gluten-Free Diet o No wheat, barley or rye o Related to gluten allergies o Makes things sticky (in bread) o In toothpaste, lip gloss, etc. • Food Sensitivities • Organic o Pesticides used on bananas also used for parkinsons • Free-Range Digestion • Need energy for protein synthesis (for our muscles) • Proteins are precursors for our neurotransmitters through amino acids • When we're eating, we need to chew our food (part of our digestive process); the more we chew our food the more it's broken down (enzymes in our saliva) • If we have any problem with absorption in our intestines, then it can leave with the waste o Lose the ability to take those nutrients and bring them into our bloodstream How does the body store what it breaks down? • Proteins are stored in the muscles The major events associated with the tree phases of energy metabolism • Gives us the energy to do anything; have thoughts, neurochemicals, immune responses etc • How we're using energy within the body Energy Metabolism • Energy availability is controlled by two pancreatic hormones o Insulin: High during cephalic and absorptive phases • Triggers glucose use as fuel by body cells • Triggers conservation of blood-borne energy to fat glycogen and protein • Triggers energy storage in adipose cells, liver, and muscles o Glucagon: High during fating phase • Triggers change of stored energy unstable fuel; fat to free fatty acids and then ketone: protein to glucose • Can we explain hunger and eating with changes in metabolism? o Feel something changing inside of us that triggers us to eat Theories of Hunger & Eating • Always trying to find homeostasis in order for us to eat Glucostatic and Lipostatic: Set-Point Theories of Hunger • Glucostatic theories: glucose levels determine when we eat • Lipostatic theories: Fat stores determine how much we eat over long term (explaining why weight tends to be constant) o If we have a lot of fat storages, then we don't need to eat so much Problems With The Set-Point Theories • These theories are contrary to evolutionary pressures that favored energy storage for survival • Reductions in blood glucose or body fat do not reliably induce eating • These theories do not account for the influence of external factors or eating and hunger • Glucose levels aren't a reliable predictor of why we decide to eat or ot • Anorexia - someone isn't eating (significantly underweight) and not motivated to eat Why do we eat? • Rat will eat food what it can smell on another rat's breath because they know that it's safe to eat • Drawn to eat because of the anticipated pleasure of eating We eat because we like it… • We are drawn to eat by the anticipated pleasure of eating o We have evolved to crave food • Multiple factors interact to determine the positive-incentive value of eating • The accounts for the impact of external factors on eating behavior What Determines What, When and How Much We Eat? • We want to eat things that have high energy, break them down and store them for their high energy content • Fiber doesn't give us a lot of nutrients; increases the bulk of our stool to help pass things out • Need sodium for action potential, etc. o Need salt in our diet • A lot of processed foods have a lot of salt in them o Makes you want to drink/eat them more → going to work off these cravings, and invite you to continue purchasing their product • Bitter taste is associated with something toxic • We can learn different preferences/aversions • Rats will prefer a diet with vitamins o Deprive an animal of vitamin b1 • Appetizer effect: Small amounts of food may increase hunger o Due to cephalic-phase responses? • Serving size: The larger the serving, generally the more consumed • Social influence o Even rats eat more when in group Satiety • Things we get that are involved in the initiation of us to stop eating • The food being in our gut ca
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