Chapter 7 Energy Metabolism Highlight 7 Alcohol and Nutrition Dr Alisha Rovner NTDT200 Fall 2013 Lecture Objectives Identify the nutrients involved in energy metabolism and the high energy compound that captures the energy released during their breakdown Explain how an excess of any of the three energyyielding nutrients contributes to body fat and how an inadequate intake of any of them shifts metabolism Describe how alcohol disrupts metabolism and impairs health Introduction Energy capacity to do work Different forms of energy include heat mechanical electrical chemical Stored in the body as chemical energy which powers myriad activities of all cells Nutrients from food provide the body with fuel through a series of reactions that release energy Clicker Question What type of energy is stored in food and in the body A Heat B Mechanical C Electrical D Chemical Chemical Reactions in the Body Metabolism Total of all of the chemical reactions that occur in living cells Body releases energy water and carbon dioxide Energy metabolism All reactions by which the body obtains and expends energy from food Chemical Reactions in the Body Anabolism reactions that involves doing work therefore requires energy Eg Glucose molecules joining together to make glycogen amino acids joining together to make proteins Catabolism breaking down of body compounds energy released Eg Breaking down proteins into amino acids Anabolic and Catabolic Reactions Compared Chemical Reactions in the Body Transfer of energy in reactions ATP Some of the energy released during catabolism is captured by adenosine triphosphate ATP a compound composed of adenine ribose 3 phosphates Body uses ATP to transfer energy released during catabolic reactions to power its anabolic reactions ATP Adenosine Triphosphate Capture and Release of Energy by ATP Chemical Reactions in the Body Enzymes proteins that act as catalysts Facilitators of metabolic reactions Coenzymes enzyme helpers Associate with enzymes Without coenzyme an enzyme cannot function Breaking Down Nutrients for Energy During digestion the body breaks down the 3 energy yielding nutrients into 4 basic units that can be absorbed Carbohydrates glucose other monosaccharides Fats triglycerides glycerol and fatty acids Proteins amino acids Breaking Down Nutrients for Energy The body uses carbohydrates and fats for most of it s energy needs Amino acids are used primarily as building blocks for proteins but do contribute 10 15 of the day s energy use Simplified Overview of EnergyYielding Pathways Review of Energy Yielding Nutrient Endpoints Feasting Excess Energy Excess protein False that protein builds only muscle not fat Excess carbohydrates Extra glucose can be converted to fat directly Excess fat Most direct and efficient conversion Almost all excess stored Transition from Feasting to Fasting During fasting carbohydrate fat and proteins are all eventually used for energy Fasting state draws on stored glycogen and adipose tissue s stored fat Several hours later most of the glucose is used up the liver s glycogen store is exhausted and blood glucose falls Fasting Inadequate Energy Adaptations to conserve energy Increases breakdown of fat to provide energy Uses glycerol and amino acids to make glucose for RBC s and CNS Creates an alternate fuel Uses fat to fuel brain Ketone bodies Suppresses appetite Slows metabolism Low Carbohydrate Diets Low carbohydrate diets create a metabolism similar to fasting Fad diets regard ketosis as key to weight loss however research doesn t support this Often the weight will return at a higher level than where the person started Adverse Side Effects of LowCarbohydrate Ketogenic Diets Metabolism Myths and Facts Claim Our metabolic rates can t change The truth While it s true that genetics help determine our metabolic rates we can boost metabolism by increasing lean muscle mass Muscle burns more calories per hour than fat which means that people with lean muscular bodies need more calories to function than people with a higher percentage of body fat Metabolism Myths and Facts Claim Very low calorie diets and skipping meals can jumpstart weight loss The truth Weight loss is all about creating an energy deficit ingesting fewer calories than your body expends each day but creating too large of a calorie deficit can backfire Severely limiting calories can make your body think it s entering a famine and that it needs to do more with fewer calories Your body adapts to the restricted caloric intake and uses fewer calories to perform the same tasks Metabolism Myths and Facts Claim A diet of green tea and chili peppers will boost metabolism The truth No magic food will speed up metabolism Some studies have shown that green tea and hot chilies temporarily boost metabolic rates but the lift is isn t enough to offset eating too many calories Metabolism Myths and Facts Claim Eating late at night slows metabolism The truth It s the extra calories not when you eat them that cause weight gain There is little evidence to support the fact that eating after 8 p m causes weight gain However you may be more likely to snack mindlessly in the evenings while watching television Calories in these snacks add up and that can cause weight gain Alcohol in the Body Highlight 7 Alcohol in the Body Alcohols class of compounds containing OH groups Glycerol Ethanol ethyl alcohol Drug Modifies body functions Offers benefits and hazards Dietary Guildelines Those who drink alcohol should do so sensibility and in moderation Up to 1 drink day for women and 2 for men Shouldn t be consumed by certain people Women of childbearing age who may become pregnant pregnant and lactating women children and adolescents those on certain medications or with medical conditions 1 serving Alcohol Each serving 1 drink 5 ounce wine 10 ounce wine cooler 12 ounce beer 1 ounce distilled liquor Alcohol s Influence Alcohol s special privileges Unlike food doesn t require time for digestion Quick absorption Slowing absorption Stomach Alcohol dehydrogenase women produce less Small intestine Priority over nutrients absorbed and metabolized first Alcohol s Influence Liver Primary site of alcohol metabolism Can process about ounce ethanol hr Disrupts liver activity Fatty liver 1st stage of liver deterioration Fibrosis 2nd stage of liver deterioration Cirrohsis most advanced stage least reversible Alcohol s Influence In the brain Narcotic drug that dulls senses induces sleep and is addictive Acts as central nervous
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