Chapter 7- Energy Balance and Obesity

Chapter 7- Energy Balance and Obesity - Chapter 7- Energy...

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Chapter 7- Energy Balance and Obesity Ecological Perspective Thrifty metabolism o A genetically determined, energy efficient metabolism, requiring few calories for daily activities. o Retain more of their body weight o In modern environment with a large surplus of calories, a thrifty metabolism contributes to the development of obesity Overview of Macronutrient Metabolism Anabolism o Body processes that create more complex chemical compounds for energy storage or for the synthesis of tissue o Body building itself (seen in infants, pregnancy, weight gain, muscle building) o Glycogen synthesis is an anabolic process Make glycogen from glucose or amino acids, but never from fat o Protein synthesis Make protein from dietary amino acids o Triglyceride synthesis Any macronutrient eaten in excess of energy needs will be converted to triglyceride and stored in adipose tissue o Insulin directs anabolism Causes glucose and fat to move into cells from the bloodstream, where they are stored or used Catabolism o Body processes that break down complex chemical compounds for energy release or for tissue breakdown o Body breaking itself down (exercise, fasting, physiological stress, when the body needs energy) o Adenosine triphosphate (ATP) is high energy chemical compound used in the body to transfer energy from nutrients to various life processes Carries energy from food to cell Powers our movement o Epinephrine, norepinephrine, and glucagon direct catabolism o We can produce ATP in a variety of ways From blood sugar, muscle glycogen, body fat sores, or breakdown of muscle protein o Anaerobic metabolism Used for high intensity exercise, energy is produced without oxygen Glucose is converted to lactic acid to produce ATP Fat can never be used as fuel anaerobically o Aerobic metabolism
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Used in lower intensities Oxygen is used for energy production Body can use carbohydrates, fatty acids and amino acids as fuel Fate of a Bowl of Oatmeal o If you went on a long bike trip and then didn’t eat that much, when you do eat your oatmeal in the morning, the starch goes partly into replenishing muscle glycogen o If you hadn’t been active yesterday and burned off your glycogen, it would go into body fat instead o Protein in the oatmeal and milk is incorporated into muscle growth stimulated by yesterday’s exercise o Without exercise, much of this would have been converted to fat and stored in adipose as well. All anabolic processes o Without having rebuilt glycogen stores, you would have to rely on fat for energy, which means you won’t be able to run as fast or burn as many calories o Fat only supports lower intensity exercise Energy Conservation of Energy o Energy can neither be created or destroyed o Goes from nuclear energy heat and light chemical energy to mechanical energy and heat energy of motion (kinetic energy) heat o All our energy comes from chemical energy stored in food, which comes
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This note was uploaded on 03/14/2012 for the course NUTRI 132 taught by Professor Anderson during the Fall '11 term at Wisconsin.

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Chapter 7- Energy Balance and Obesity - Chapter 7- Energy...

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