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Unformatted text preview: Energy Balance: Study Questions Synopsis : Drawing on fundamental biology & physics concepts, this lecture begins by defining energy. We then apply this knowledge to the human nutrition by looking at food sources, the thermic effect ō food, & more. Energy usage & energy balance are defined & further explored through discussing obesity. (Underweight will be examined more thoroughly in the next major course topic: “Eating Disorders.” As w/ most topics in this course, the nutritional implications ō the energy balance concept are examined as well as some principles you can apply when making dietary choices. I. Overview a. Thermodynamic law “Conservation ō Energy” b. Biological energy comes ultimately from sunlight c. Energy units d. Food sources e. Energy Balance * Energy intake = energy expenditure * Negative balance: underweight or losing * Positive balance: obesity or gaining Energy What do we mean by the conservation ō energy? Energy can neither be created nor destroyed (can change form very readily) . What is the ultimate source ō all biological energy? What is the process that converts this energy into biological energy? What chemical does it require? What is its product? Solar energy is the ultimate source ō all biological energy. Photosynthesis is the process that converts solar energy into biological energy. It requires CO 2 (& H 2 O) . Its product is C 6 H 12 O 6 (& H 2 O) . photosynthesis equation :- 6CO 2 + 6H 2 O + sunlight – chlorophyll → C 6 H 12 O 6 + 6H 2 O- carbon dioxide + water + sunlight = glucose + water- store solar energy in chemical bonds ō glucose- solar → chemical → mechanical energy/movement- Biological energy is derived from energy in chem. bonds ō nutrient molecules. We release this energy & convert it to mechanical energy & heat. Units ō energy What units do we use to measure energy? We use kilocalories ( kcal ) as units to measure energy. Food sources We take simple nutrient molecules like glucose, FAs, & AAs extracted from our diet & build them into complex molecules & structures like glycogen, lipid, & protein. This allows us to store energy & to make cells & tissues needed by body. We can also break down both energy stores & dietary energy sources to release this energy for our needs. This synthesis & breakdown are anabolism & catabolism, respectively.- store fat = energy = weight- excess ō macronutrients : stored as body fat What are the four sources ō energy? How many kcals per gram do each ō them yield? Which one is not an essential nutrient? 4 Sources ō Energy : 1) Protein : 4 kcal/g 2) Carbohydrates : 4 kcal/g 3) Fat/Lipid : 9 kcal/g 4) Alcohol : 7 kcal/g (non-essential nutrient) Energy balance What do we mean by energy balance? What is the basic equation ō energy balance?...
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This note was uploaded on 03/29/2008 for the course NUTRI SCI 132 taught by Professor Anderson during the Spring '08 term at University of Wisconsin.
- Spring '08