NUTR 470 1st Edition Lecture 1Introduction – Energy Metabolism • Energy required for:-the maintenance of biological functions-Health-Growth-physical activities • Energy expenditure by the body when at rest, but not asleep, under uncontrolled conditions of thermal neutrality, measured about 12 h after the last meal. • Basal metabolic rate (BMR) -Sedentary activities (1.1 – 1.2 . BMR) -Moderate activity (2 – 5 . BMR) -Vigorous activities (6 – 8 . BMR) • This is calculated by multiplying the standard (BMR x activity factor)• Energy is generated from food.• Energy sources -Lipids: 9 kcal/g -Carbohydrates: 4 kcal/g -Proteins: 4 kcal/g -Alcohol: 7 kcal/g• Estimation of energy requirement -Energy requirement is estimated by measurement of energy expenditure. -Direct calorimetry: Measurement of heat -Indirect calorimetry: Measurement of oxygen consumption • RQ stands for respiratory quotient, which is the ratio of the production of CO2 to the consumption of O2. -A change in RQ indicates a shift in fuel utilization-Is always between (.7-1)-Fasting decreases RQ-Values of food:• Carbohydrates: -Vo2 (L): 0.827 -Vco2 (L): 0.827 -RQ: 1.000 These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.• Lipids-Vo2 (L): 2.018 -Vco2 (L): 1.435 -RQ: 0.710 • Proteins (1 g) -Vo2 (L): 1.010 -Vco2 (L): 0.843 -RQ: 0.835 • Questions Regarding RQ -Can a RQ value measured from a mouse at of a given time pointed be 1 or 0.7? Why?• No. Glucose and lipid are burned at the same time. -What information can RQ data provide? • 1. Energy expenditure (EE = (3.185 + 1.232 . RQ) .Vo2) • 2. The shift between glucose and lipid as energy source. • Substrate-level phosphorylation -Glycolysis (2ATP) -TCA (1ATP) -Respiratory chain -Oxidative phosphorylation • Reducing equivalents are collected by respiratory chain for oxidation and coupled generation of ATP. • Energy balance (homeostasis) -Energy (food) intake -Energy expenditure • Imbalance of energy -Malnutrition or undernutrition -Overnutrition • Malnutrition-Negative energy balance between intake and expenditure -Poor nutrition can influence the development of certain chronic diseases. -Resulting from poor diets and from disease states • Obesity — Overnutrition-Positive energy balance between intake and expenditure -Obesity is the major risk factor of insulin resistance. -Obesity is highly associated with type 2 diabetes and causes and exacerbates many health problems. • Obesity – Scientific Principle -Obesity is a medical problem. -Elevated circulating levels of free fatty acids • Lipo-toxicity (beta cells)-Changes in circulating levels of adipokines • Leptin, adiponectin, resistin, and tumor necrosis factor alpha -Secondary effects on the liver and the muscle • Hepatic insulin resistance • Muscle insulin resistance -Obesity is the major risk factor of cardiovascular diseases • Elevated circulating levels of LDL -Endothelial lesion • Decreased levels of HDL -Cytoprotection • Summary - Energy - Generation of energy from foods - Basal Metabolic Rates - Energy balance and obesity -