Chapter 5
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Questions and Answers

What does the First Law of Thermodynamics state?

  • Energy cannot be created or destroyed. (correct)
  • Energy is always in motion.
  • Energy can be created or destroyed.
  • Energy can be transformed but not transferred.

    • Which of the following components is part of Energy Out?

  • Physical activity level (correct)
  • Thermal effect of food (correct)
  • Basal metabolic rate (correct)
  • Dietary intake

    • What is the primary source of energy that sustains life on Earth?

  • Solar energy from the sun (correct)
  • Chemical energy from food
  • Energy produced during exercise
  • Energy derived from fats

    • How do carbohydrates primarily store energy?

    <p>In glycogen form</p> Signup and view all the answers

    What role does photosynthesis play in the energy transfer process?

    <p>It transforms solar energy into chemical energy.</p> Signup and view all the answers

    Which macronutrients are primarily responsible for providing usable energy currency in the form of ATP?

    <p>Fats and carbohydrates</p> Signup and view all the answers

    What is metabolism most closely related to?

    <p>Chemical processes that provide energy</p> Signup and view all the answers

    Which of the following best describes energy balance?

    <p>The relationship between energy intake and energy expenditure</p> Signup and view all the answers

    What happens when an individual consumes more calories than they expend?

    <p>Energy is stored as fatty acids, muscle tissue, or organs.</p> Signup and view all the answers

    Which factor contributes to the increasing rates of obesity and overweight?

    <p>Increased caloric intake combined with decreased caloric expenditure.</p> Signup and view all the answers

    What is one major reason for growing energy surplus globally?

    <p>Growing supply of cheap caloric dense foods.</p> Signup and view all the answers

    How did food consumption per person change from 1969/1971 to 1999/2001?

    <p>It increased by almost 400 kcal per person per day.</p> Signup and view all the answers

    What is a primary strategy for a Nutrition Coach in managing weight?

    <p>Modulating energy balance through planning periods of both negative and positive energy balance.</p> Signup and view all the answers

    Which of the following is NOT a factor influencing energy balance?

    <p>Weather patterns.</p> Signup and view all the answers

    What has likely contributed to the reduction in caloric expenditure globally?

    <p>Rise in sedentary activities like screen time.</p> Signup and view all the answers

    What is a consequence of the rising caloric intake per person?

    <p>Higher energy balance resulting in weight gain.</p> Signup and view all the answers

    What is the primary function of adenosine triphosphate (ATP) in living organisms?

    <p>To provide energy for physiological processes</p> Signup and view all the answers

    Which factor does NOT influence Total Daily Energy Expenditure (TDEE)?

    <p>Sleep duration</p> Signup and view all the answers

    What happens to potential energy from food when consumed?

    <p>It is converted into kinetic energy for work</p> Signup and view all the answers

    The concept of energy balance involves which key components?

    <p>Calories consumed minus calories expended</p> Signup and view all the answers

    According to the First Law of Thermodynamics, what can be said about energy?

    <p>Energy can be transformed but not created or destroyed</p> Signup and view all the answers

    How does the body primarily lose energy during metabolism?

    <p>As heat released into the environment</p> Signup and view all the answers

    What is a key source of potential energy in the human body?

    <p>Chemical bonds in food</p> Signup and view all the answers

    What is the primary role of non-exercise activity thermogenesis (NEAT)?

    <p>To reflect energy expended in daily activities</p> Signup and view all the answers

    Which of the following best describes metabolism?

    <p>The conversion of food into energy and heat</p> Signup and view all the answers

    Which macronutrient is typically used for quick energy during short-term intense exercise?

    <p>Carbohydrates</p> Signup and view all the answers

    What is the average calorie requirement for humans based on Total Daily Energy Expenditure?

    <p>2,500 calories per day</p> Signup and view all the answers

    What does TDEE primarily account for?

    <p>The total energy needs, including various factors</p> Signup and view all the answers

    Which process is described as the generation of kinetic energy from potential energy sources?

    <p>Metabolism</p> Signup and view all the answers

    When one phosphate group is broken off from ATP, what is formed?

    <p>Adenosine triphosphate (ADP)</p> Signup and view all the answers

    What process is responsible for converting solar energy into chemical energy in plants?

    <p>Photosynthesis</p> Signup and view all the answers

    Which of the following is a key component of energy out?

    <p>All of the above</p> Signup and view all the answers

    What role does glycogen play in energy metabolism?

    <p>It serves as a storage form of energy.</p> Signup and view all the answers

    Which macronutrient is primarily broken down to release immediate energy?

    <p>Carbohydrates</p> Signup and view all the answers

    How is potential energy from food primarily utilized in the human body?

    <p>Converted into biochemical energy</p> Signup and view all the answers

    Which factor influences energy in by affecting food intake?

    <p>Lifestyle habits</p> Signup and view all the answers

    What is the primary form of energy currency used by living organisms?

    <p>ATP</p> Signup and view all the answers

    In addition to food intake, what else plays a crucial role in the energy balance equation?

    <p>Exercise frequency</p> Signup and view all the answers

    What is the primary purpose of ATP in living organisms?

    <p>To provide energy for physiological processes</p> Signup and view all the answers

    Which factors are necessary to calculate Total Daily Energy Expenditure (TDEE)?

    <p>Thermic effect of feeding and resting metabolic rate</p> Signup and view all the answers

    Which of the following best describes the concept of energy balance?

    <p>Comparing energy intake with energy output</p> Signup and view all the answers

    What happens to the energy from consumed calories that exceeds energy expenditure?

    <p>It is stored for later use</p> Signup and view all the answers

    What is the primary energy requirement for basal metabolic functions?

    <p>2000 calories per day</p> Signup and view all the answers

    How does the human metabolism primarily utilize food?

    <p>To generate heat and perform physical activity</p> Signup and view all the answers

    Which chemical compound is formed when a phosphate group is removed from ATP?

    <p>Adenosine diphosphate (ADP)</p> Signup and view all the answers

    What is the main energy source stored in adipose tissue?

    <p>Fats</p> Signup and view all the answers

    Which aspect does NOT contribute to a person's Total Daily Energy Expenditure?

    <p>Amount of sleep</p> Signup and view all the answers

    What type of energy transformation occurs during the digestion of food?

    <p>Chemical to kinetic energy</p> Signup and view all the answers

    In terms of energy requirements, what does NEAT stand for?

    <p>Non-exercise activity thermogenesis</p> Signup and view all the answers

    What energy-related phenomenon is demonstrated by a boiling kettle?

    <p>Transfer of heat energy to produce work</p> Signup and view all the answers

    How is energy from food primarily transformed for physical activities?

    <p>From potential to kinetic energy</p> Signup and view all the answers

    Which statement best describes the First Law of Thermodynamics?

    <p>Energy can be transformed, but not destroyed</p> Signup and view all the answers

    Which of the following activities would contribute most to increasing NEAT?

    <p>Walking to a colleague's desk instead of emailing</p> Signup and view all the answers

    What is a recommended approach to maintaining a healthy diet?

    <p>Incorporating all three macronutrients in a balanced way</p> Signup and view all the answers

    What role does sleep deprivation potentially play in energy metabolism?

    <p>It may decrease resting metabolic rate (RMR) and increase energy intake</p> Signup and view all the answers

    How can non-exercise activity thermogenesis (NEAT) be increased in daily life?

    <p>By implementing standing desks</p> Signup and view all the answers

    Which of the following statements about daily physical activity is true?

    <p>Less than 5% of adults participate in 30 minutes of physical activity daily</p> Signup and view all the answers

    What is one major consequence of a sedentary lifestyle on public health?

    <p>Increased rates of obesity and chronic diseases</p> Signup and view all the answers

    Which activity would least likely promote NEAT?

    <p>Staying seated during a two-hour meeting</p> Signup and view all the answers

    What is the primary role of Resting Metabolic Rate (RMR)?

    <p>It represents the total calories burned while at rest.</p> Signup and view all the answers

    Which component contributes the most variability to an individual's daily energy expenditure?

    <p>Thermic Effect of Activity (TEA)</p> Signup and view all the answers

    What might be a result of diets that restrict a macronutrient?

    <p>Potentially unsuccessful weight management outcomes</p> Signup and view all the answers

    How does a high percentage of body fat affect Resting Metabolic Rate (RMR)?

    <p>It decreases RMR.</p> Signup and view all the answers

    What does the term MET represent?

    <p>Resting metabolic equivalent for energy expenditure calculations</p> Signup and view all the answers

    What factors can influence a person's NEAT levels?

    <p>Lifestyle and activity levels</p> Signup and view all the answers

    The Thermic Effect of Feeding (TEF) accounts for what approximate percentage of daily energy expenditure?

    <p>10%</p> Signup and view all the answers

    What effect does prolonged dieting have on Resting Metabolic Rate (RMR)?

    <p>It may suppress RMR in the short term.</p> Signup and view all the answers

    What risk is associated with sleeping less than 5 hours per night?

    <p>Increased odds of obesity compared to those who sleep 7 to 8 hours</p> Signup and view all the answers

    What are the potential consequences of frequent weight cycling on RMR?

    <p>It does not appear to have a long-term effect on RMR.</p> Signup and view all the answers

    Which activity would be beneficial for promoting a higher metabolic rate?

    <p>Walking or cycling instead of driving</p> Signup and view all the answers

    What is a likely effect of inadequate sleep on food choices?

    <p>Higher likelihood of choosing high-fat, sugar-dense foods</p> Signup and view all the answers

    Which factor is likely to influence energy balance negatively?

    <p>Increased sedentary activities.</p> Signup and view all the answers

    What trend has been observed regarding the availability of calorically dense foods globally?

    <p>A dramatic increase due to agricultural practices.</p> Signup and view all the answers

    What can be an effective way to increase physical activity during leisure time?

    <p>Playing active games with family or friends</p> Signup and view all the answers

    How does age affect Resting Metabolic Rate (RMR)?

    <p>RMR declines by 2% to 3% per decade.</p> Signup and view all the answers

    What effect does sleep deprivation have on resting metabolic rate (RMR)?

    <p>RMR decreases by 2.6%</p> Signup and view all the answers

    Which of these influences directly affects the Thermic Effect of Activity (TEA)?

    <p>Overall activity levels, both planned and spontaneous.</p> Signup and view all the answers

    In terms of energy balance, which of the following is an indicator of obesity risk?

    <p>Long-term energy surplus.</p> Signup and view all the answers

    How many extra calories do sleep-deprived individuals consume on average per day?

    <p>385 calories</p> Signup and view all the answers

    What has contributed to the increased rates of caloric intake globally?

    <p>Improved access to a diversity of foods.</p> Signup and view all the answers

    What hormonal change occurs in sleep-deprived individuals related to hunger?

    <p>Decreased plasma leptin and increased ghrelin</p> Signup and view all the answers

    Which hormone is primarily responsible for increasing blood glucose levels during stress?

    <p>Cortisol</p> Signup and view all the answers

    Which meal component is associated with the highest Thermic Effect of Feeding (TEF)?

    <p>Proteins</p> Signup and view all the answers

    What happens to energy when an individual expends more calories than they consume?

    <p>Energy is lost from the body.</p> Signup and view all the answers

    What impact does hyperthyroidism have on resting energy expenditure?

    <p>Increases resting energy expenditure</p> Signup and view all the answers

    Which hormone is involved in regulating metabolism and has a major influence on body composition in men?

    <p>Testosterone</p> Signup and view all the answers

    Why is it impractical to account for all facets of energy balance on a daily basis?

    <p>Multiple factors influence and alter energy intake and expenditure.</p> Signup and view all the answers

    What is a possible outcome of cortisol release during stress?

    <p>Increased heart rate</p> Signup and view all the answers

    Which component is NOT considered a part of energy in regulations?

    <p>Water intake</p> Signup and view all the answers

    The production of which hormone helps control hunger sensations?

    <p>Leptin</p> Signup and view all the answers

    What are thyroid hormones primarily responsible for in relation to energy metabolism?

    <p>Stimulating metabolism and regulating energy balance</p> Signup and view all the answers

    Which of the following factors influence appetite regulation?

    <p>Hormonal signals and social factors</p> Signup and view all the answers

    What is the role of cortisol in energy metabolism during stress?

    <p>Stimulates gluconeogenesis</p> Signup and view all the answers

    What effect does sleep deprivation have on calorie consumption from different food types?

    <p>Increases consumption of fatty foods</p> Signup and view all the answers

    Which is a complexity of the Energy In component of energy balance?

    <p>Individual variation affects food choices and digestion</p> Signup and view all the answers

    What is the primary function of leptin in the body?

    <p>Decrease appetite</p> Signup and view all the answers

    Which hormone is primarily responsible for stimulating appetite?

    <p>Ghrelin</p> Signup and view all the answers

    What effect does low leptin levels have on the body?

    <p>Increased appetite</p> Signup and view all the answers

    What triggers the release of CCK in the gastrointestinal system?

    <p>The entry of amino acids or fatty acids</p> Signup and view all the answers

    How does insulin help regulate blood sugar levels?

    <p>Increases glucose uptake in peripheral tissues</p> Signup and view all the answers

    Which hormone opposes the action of insulin when blood sugar levels are low?

    <p>Glucagon</p> Signup and view all the answers

    What role does Neuropeptide Y (NPY) have in the body?

    <p>Stimulate appetite and fat storage</p> Signup and view all the answers

    What influence does psychological distress have on eating behaviors?

    <p>It alters eating behaviors towards high-energy foods.</p> Signup and view all the answers

    How do larger body sizes relate to leptin levels?

    <p>Higher BMI is linked to larger quantities of leptin.</p> Signup and view all the answers

    What is a potential risk of dysregulated leptin signaling during weight loss?

    <p>Uncontrolled weight gain</p> Signup and view all the answers

    Which factor can significantly impact food choices and eating behaviors?

    <p>Access to affordable healthy food</p> Signup and view all the answers

    What effect does high-energy food consumption have on the risk of obesity?

    <p>It increases obesity risk.</p> Signup and view all the answers

    What is the primary action of ghrelin in the body?

    <p>Stimulate appetite and food intake</p> Signup and view all the answers

    What is the primary motivator for hedonistic eating?

    <p>Pleasure</p> Signup and view all the answers

    Which hormone is likely involved in regulating reward mechanisms in hedonistic eating?

    <p>Ghrelin</p> Signup and view all the answers

    Which of the following is NOT a recommended strategy for practicing mindful eating?

    <p>Eating quickly</p> Signup and view all the answers

    What can be a consequence of emotional eating?

    <p>Increased feelings of guilt</p> Signup and view all the answers

    How does skipping meals affect mindful eating choices?

    <p>It makes mindful choices harder.</p> Signup and view all the answers

    What does food processing refer to?

    <p>Any alteration of food from its natural state.</p> Signup and view all the answers

    How does the state of food processing impact nutrient availability?

    <p>It can alter the way the body absorbs certain nutrients.</p> Signup and view all the answers

    What impact can emotional eating have on weight management?

    <p>It may lead to overeating and weight gain.</p> Signup and view all the answers

    How many ATP molecules are produced from complete oxidation of one glucose molecule through the aerobic energy system?

    <p>36 ATP</p> Signup and view all the answers

    During high-intensity exercise, what is the primary source of ATP production?

    <p>Muscle glycogen</p> Signup and view all the answers

    Which of the following conditions is related to variations in digestion and metabolism?

    <p>All of the above</p> Signup and view all the answers

    What role does beta-oxidation play in fat metabolism?

    <p>Forms acetyl-CoA from free fatty acids</p> Signup and view all the answers

    What is a potential positive aspect of food processing?

    <p>Makes food safer and easier to transport.</p> Signup and view all the answers

    Which metabolic pathway uses pyruvate to generate energy?

    <p>Krebs cycle</p> Signup and view all the answers

    How can emotional hunger be differentiated from physical hunger?

    <p>Physical hunger comes on gradually.</p> Signup and view all the answers

    What role do gut microbes play in digestion?

    <p>They can influence digestion and metabolism rates.</p> Signup and view all the answers

    Which of the following is NOT a fuel source for the aerobic energy system?

    <p>Glutamine</p> Signup and view all the answers

    Which of these behaviors is recommended for mindful eating?

    <p>Chewing thoroughly before swallowing.</p> Signup and view all the answers

    What is produced at the end of the electron transport chain?

    <p>Water and ATP</p> Signup and view all the answers

    What is a likely effect of hedonic eating on the brain?

    <p>Increased activation of reward signals.</p> Signup and view all the answers

    How does the calorie yield from one molecule of palmitic free fatty acid compare to glucose?

    <p>Palmitic yields significantly more ATP</p> Signup and view all the answers

    What best describes the relationship between exercise intensity and fuel utilization?

    <p>Higher intensity relies primarily on carbohydrates, while lower intensity uses fat</p> Signup and view all the answers

    Which process precedes the Krebs cycle in glucose metabolism?

    <p>Glycolysis</p> Signup and view all the answers

    What primary factor influences the ATP production pathway utilized during physical activity?

    <p>Intensity of the activity</p> Signup and view all the answers

    What is the primary energy source for the body that must be produced from food?

    <p>ATP</p> Signup and view all the answers

    Which metabolic pathway is primarily used for immediate energy during high-intensity activity?

    <p>ATP-PC system</p> Signup and view all the answers

    What is the main limiting factor of the ATP-PC system?

    <p>Phosphocreatine stores</p> Signup and view all the answers

    How long can the ATP-PC system provide energy during high-intensity exercise?

    <p>10 to 15 seconds</p> Signup and view all the answers

    What is the primary energy system used for high-intensity exercise lasting up to 10 seconds?

    <p>ATP-PC system</p> Signup and view all the answers

    What happens to ATP and phosphocreatine stores during extended high-intensity exercise?

    <p>They are exhausted and take time to replenish.</p> Signup and view all the answers

    What is formed when a phosphate group is removed from ATP?

    <p>ADP and free phosphate</p> Signup and view all the answers

    How long can the anaerobic glycolytic system sustain energy during high-intensity exercise?

    <p>10 seconds to 2 minutes</p> Signup and view all the answers

    What type of energy production involves the transfer of electrons between molecules?

    <p>Cellular respiration</p> Signup and view all the answers

    What is the end product of glycolysis when limited oxygen is available?

    <p>Lactic acid</p> Signup and view all the answers

    What happens to pyruvate if sufficient oxygen is available?

    <p>It supports energy production in the Krebs cycle</p> Signup and view all the answers

    Which nutrient is primarily broken down for immediate energy during exercise?

    <p>Carbohydrates</p> Signup and view all the answers

    What is the primary function of creatine kinase in the ATP-PC system?

    <p>Break down phosphocreatine into creatine and inorganic phosphate</p> Signup and view all the answers

    Which system uses glucose as a primary fuel source?

    <p>Glycolytic system</p> Signup and view all the answers

    Which of the following activities predominantly relies on the aerobic energy system?

    <p>Long-distance running</p> Signup and view all the answers

    What role does creatine kinase play in the ATP-PC system?

    <p>It breaks down phosphocreatine.</p> Signup and view all the answers

    What occurs to ADP and a free phosphate molecule during the ATP production cycle?

    <p>They combine to create ATP.</p> Signup and view all the answers

    What is the typical duration of exercise that the aerobic system can sustain?

    <p>2 minutes to several hours</p> Signup and view all the answers

    When does the body primarily rely on the ATP-PC system?

    <p>During the first few seconds of exercise.</p> Signup and view all the answers

    What is the respiratory exchange ratio (RER) indicative of when it is around 0.70?

    <p>Primarily fat as fuel</p> Signup and view all the answers

    What is a common misconception about lactic acid in relation to muscle soreness?

    <p>Lactic acid is the primary cause of muscle soreness</p> Signup and view all the answers

    How does the body replenish phosphocreatine stores after exercise?

    <p>During rest periods.</p> Signup and view all the answers

    How long does it typically take for phosphocreatine (PC) stores to replenish after exercise?

    <p>2 minutes</p> Signup and view all the answers

    What is a further consideration regarding the use of energy systems during exercise?

    <p>Multiple energy systems are involved to meet demands.</p> Signup and view all the answers

    What determines the dominance of anaerobic glycolysis during exercise?

    <p>Intensity of exercise</p> Signup and view all the answers

    What happens to lactate produced during anaerobic glycolysis?

    <p>It can be converted back to pyruvate in the liver</p> Signup and view all the answers

    Which of the following factors does NOT affect muscle performance during high-intensity exercise?

    <p>Availability of oxygen</p> Signup and view all the answers

    What is the key difference between the ATP-PC system and the anaerobic glycolytic system?

    <p>Energy supply duration</p> Signup and view all the answers

    Study Notes

    Energy Metabolism

    • The First Law of Thermodynamics: Energy cannot be created or destroyed, only transformed from one form to another.
    • Energy Balance: The balance between energy intake (calories consumed) and energy expenditure (calories burned).
    • ATP: Adenosine triphosphate is the primary energy currency of the body, providing energy for muscle contraction, nerve impulses, and most bodily functions.
    • Total Daily Energy Expenditure (TDEE): The estimated calorie needs per day, influenced by age, sex, physical activity, and other factors
    • Energy In: Includes all calories consumed from food and beverages.
    • Energy Out: Includes the calories burned during digestion (TEF), non-exercise activity (NEAT), and exercise (TEA)

    Maintaining Energy Balance

    • Maintaining a balance between Energy In and Energy Out is crucial for health and performance.
    • Energy surplus (more calories consumed than burned) results in weight gain.
    • Energy deficit (more calories burned than consumed) results in weight loss.
    • Factors Influencing Energy Balance: Age, sex, genetics, activity levels, diet, environment, and numerous other factors.
    • Global trends: Increased availability of calorie-dense foods and decreased physical activity contribute to a global energy surplus and rising obesity rates.

    First Law of Thermodynamics

    • Energy is conserved
    • Not created nor destroyed
    • Energy is transformed from one form to another
    • Example: Calories consumed are either used for energy, sustaining life, given off as heat, or stored

    Energy Expenditure

    • Energy out
    • Calories burned during digestion, non-exercise activity, and exercise
    • Four components of energy expenditure: Resting Metabolic Rate, Thermic Effect of Food, Thermic Effect of Activity, and Non-Exercise Activity Thermogenesis

    Resting Metabolic Rate (RMR)

    • Calories burned when the body is at rest
    • Supports breathing, blood circulation, organ function, and neurological function
    • Proportional to lean body mass, decreasing with body fat increase
    • Decreases with age due to loss of lean body mass
    • May be regulated by prolonged dieting and weight cycling, though research is inconclusive

    Thermic Effect of Food (TEF)

    • Increase in energy expenditure after consuming a meal
    • Energy used to digest food
    • Account for approximately 10% of daily energy expenditure
    • Protein has the highest thermic effect, followed by carbohydrates, and then fats

    Thermic Effect of Activity (TEA)

    • Account for variability in daily energy expenditure
    • Includes energy expended during physical work, muscular activity, exercise, and structured exercise
    • Maintains a healthy body weight and raises RMR

    Non-Exercise Activity Thermogenesis (NEAT)

    • Energy expended during daily activities other than sleeping, eating, or exercising
    • Includes activities like walking at work, typing, walking to meetings, and fidgeting
    • More active lifestyles result in higher NEAT
    • Contributes to weight maintenance or weight loss

    Energy Balance

    • Balance between energy consumed (calories in) and energy expended (calories out)
    • Overconsumption leads to energy storage
    • Underexpending leads to energy loss
    • Influenced by individual factors and total daily energy expenditure (TDEE)

    Factors Influencing Energy Balance

    • Increased caloric intake
    • Decreased caloric expenditure
    • Availability of cheap, calorie-dense food
    • Sedentary lifestyles
    • Less occupational and domestic work
    • Less physical activity

    Components of Energy Out

    • Resting Metabolic Rate (RMR)
    • Thermic Effect of Feeding (TEF)
    • Thermic Effect of Activity (TEA)
    • Non-Exercising Activity Thermogenesis (NEAT)

    Activities to Promote NEAT

    • Do additional tasks around the house
    • Play with children
    • Take 10-minute walks every 2 hours
    • Walking meetings instead of sitting
    • Stand-up desk or exercise ball
    • Pedometer or smartwatch for activity tracking
    • Pace and fidget more
    • Take the stairs
    • Adopt a more active lifestyle
    • Walk or cycle instead of driving
    • Manual tools and utensils instead of powered versions

    Sleep and Energy Balance

    • Sleep deprivation or restriction may reduce RMR and increase energy intake
    • Leads to positive energy balance and weight gain
    • Compromised sleep patterns are associated with increased odds of obesity

    Metabolic Equivalent (MET)

    • Measure of energy expenditure
    • One MET is equivalent to 3.5 ml O2 / Kg/min
    • Used to prescribe exercise training intensities
    • Example: Leisurely walking is 2.5 METs, brisk walking is 5 METs

    Sleep Deprivation and Weight Gain

    • Sleep deprivation can lead to an increased risk of obesity.
    • Reduced sleep duration (4 hours/night for 5 nights) decreased resting metabolic rate (RMR) by 2.6%.
    • Sleep-deprived individuals consume more calories from fatty foods than protein.
    • Sleep deprivation can alter hormonal levels (leptin & ghrelin) that regulate hunger.

    Energy Out: Hormones

    • Thyroid hormones regulate metabolism, growth and development.
    • Hyperthyroidism is characterized by increased resting energy expenditure and weight loss.
    • Hypothyroidism is characterized by reduced resting energy expenditure and weight gain.
    • Cortisol is released in response to stress, increasing blood glucose levels and stimulating gluconeogenesis.
    • Testosterone plays a role in carbohydrate, fat, and protein metabolism, and deficiency can lead to increased fat mass and impaired glucose tolerance.

    Energy In: Appetite

    • Leptin decreases appetite by signaling to the brain that enough food has been consumed.
    • Ghrelin stimulates appetite and promotes fat storage.
    • Cholecystokinin (CCK) stimulates digestion of fat and protein.
    • Neuropeptide Y (NPY) stimulates appetite and fat storage.

    Environmental Factors

    • Busy schedules can lead to poor food choices and eating behaviors.
    • Access to affordable healthy food influences the quality and amount of calories consumed.
    • Psychological distress can alter eating behaviors, leading to increased intake of energy-dense foods.

    Individual Variation

    • There are individual differences in energy expenditure and nutrient absorption.
    • Food processing affects nutrient availability and digestive processes.

    Metabolic Energy Systems

    • Energy is obtained from carbohydrates, proteins, and fats.
    • ATP is the primary energy source for the body.
    • Food is broken down into its simplest forms (glucose, fatty acids, and amino acids) during digestion.
    • Carbohydrates, proteins, and fats are metabolized to create ATP from ADP and free phosphate molecules.

    ATP & Energy Systems

    • The human body stores a limited amount of ATP, enough for a few seconds of intense activity.
    • Three primary energy systems (ATP-PC, Anaerobic Glycolytic System, and Aerobic System) are used continuously, with their roles determined by the intensity and duration of the activity.
    • Each system utilizes different fuel sources (ATP, PC, glucose, glycogen, fat) and replenishes ATP through distinct metabolic processes.

    ATP-PC System (Phosphagen System)

    • This system provides energy for short, intense bursts of activity lasting up to about 10 seconds.
    • It uses the energy released from the breakdown of phosphocreatine (PC) stored in muscles.
    • It is the quickest way to resynthesize ATP, but its limited PC stores lead to rapid fatigue.
    • Creatine kinase breaks down PC into creatine and inorganic phosphate (Pi), releasing energy to form ATP.
    • PC stores are replenished after about 2 minutes of rest.

    Anaerobic (Glycolytic) System

    • This system provides energy for medium to high-intensity activity lasting between 10 seconds and 2 minutes.
    • It uses glucose from the blood or glycogen stored in muscles.
    • Glycolysis generates ATP anaerobically by breaking down glucose.
    • The end product of glycolysis is pyruvate, which can be converted into lactate or used in the Krebs cycle.
    • The availability of oxygen determines the fate of pyruvate.

    Aerobic Energy System

    • This system provides energy for long-duration, low-intensity activities lasting from 2 minutes to several hours.
    • It relies on oxygen for fuel and utilizes a mix of fat and carbohydrates.
    • As exercise intensity increases, more carbohydrates are used, and at maximum levels, primarily rely on carbohydrates.
    • The aerobic system includes the Krebs cycle and the electron transport chain, which generate ATP in mitochondria.
    • Glucose, glycogen, plasma-free fatty acids, and intramuscular triglycerides are utilized as fuel.
    • Complete oxidation of glucose through all steps (glycolysis, Krebs cycle, electron transport chain) produces approximately 36 ATP molecules per molecule of glucose.
    • Fat can also be used as energy for this system through beta-oxidation.

    Energy System Utilization

    • The primary energy system used depends on the activity's intensity and duration.
    • High-intensity, short-duration activities (e.g., sprints) primarily rely on ATP-PC and anaerobic glycolytic systems.
    • Moderate-intensity, longer-duration activities (e.g., cycling) predominantly use the aerobic system.

    Getting Technical

    • The respiratory exchange ratio (RER) measures the ratio of carbon dioxide produced to oxygen consumed.
    • RER can be used to assess the primary fuel source being utilized (e.g., RER of 0.70 suggests mainly fat, 1.00 or above indicates primarily carbohydrates).

    Summary

    • Understanding energy systems is essential for coaches, trainers, and nutritionists to optimize athletic performance and manage body weight.
    • By manipulating energy intake (food) and energy expenditure (activity), individuals can effectively manage their body composition.

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    Explore the fundamentals of energy metabolism, including the First Law of Thermodynamics, energy balance, and the role of ATP. Understand how total daily energy expenditure and the balance between energy intake and expenditure affect health and performance.

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