EHR 522 weeks 1 - 4
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Questions and Answers

What is the purpose of intraluminal hydrolysis in carbohydrate digestion?

  • To break down starch to oligosaccharides (correct)
  • To absorb monosaccharides into the bloodstream
  • To break down oligosaccharides to monosaccharides
  • To synthesize glycogen

    • Dietary fibre is a type of digestible polymer.

    False

    What is the name of the membrane protein responsible for glucose and galactose uptake at the apical membrane?

    Sodium/glucose transporter 1 (SGLT1)

    The storage form of carbohydrate in animals is ______________.

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

    Match the following enzymes with their functions in carbohydrate digestion:

    <p>Salivary amylase = Breaks down starch to oligosaccharides in the mouth Pancreatic alpha-amylase = Breaks down starch to oligosaccharides in the small intestine Lactase = Breaks down lactose to glucose and galactose Sucrase-isomaltase = Breaks down sucrose to glucose and fructose</p> Signup and view all the answers

    What is the primary function of the stomach in the gastrointestinal system?

    <p>Temporary food storage and digestion</p> Signup and view all the answers

    The large intestine is responsible for the absorption of nutrients.

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

    What are the three major groups of carbohydrates classified into?

    <p>Monosaccharides, Disaccharides, and Polysaccharides.</p> Signup and view all the answers

    The pancreas secretes _______________________ to neutralise gastric acid.

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

    What happens to the oligopeptides after they are digested by luminal enzymes?

    <p>They are further digested by cytosolic enzymes to produce intracellular amino acids</p> Signup and view all the answers

    Match the following organs with their functions:

    <p>Mouth and Oropharynx = Mechanical breakdown and lubrication of food Small Intestine = Continues digestion and primary site for nutrient absorption Liver = Bile secretion and storage in the gallbladder between meals</p> Signup and view all the answers

    The nine essential amino acids can be synthesised in adequate amounts by the human body.

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

    What is the main difference in protein absorption between adults and neonates?

    <p>Adults absorb proteins in the form of amino acids and small peptides, while neonates absorb whole proteins through apical pinocytosis.</p> Signup and view all the answers

    Proteins are digested by gastric and pancreatic proteases, which are secreted as _______________.

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

    Match the following sources with their corresponding roles in protein digestion:

    <p>Dietary proteins = Provide essential amino acids Endogenous proteins = Form a source of protein for digestion Proenzymes = Require conversion to their active form for protein hydrolysis to occur Brush border peptidases = Digest some oligopeptides to amino acids</p> Signup and view all the answers

    Which of the following is an active transport process?

    <p>Glucose moving against its concentration gradient</p> Signup and view all the answers

    SGLT1 can carry fructose.

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

    What is the first step in protein digestion and absorption?

    <p>Proteins must first be digested into their constituent oligopeptides and amino acids</p> Signup and view all the answers

    The facilitated sugar transporter responsible for the exit of monosaccharides across the basolateral membrane is called __________________.

    <p>GLUT2</p> Signup and view all the answers

    Match the following protein digestion pathways with their descriptions:

    <p>Pathway 1 = Proteins are hydrolyzed to peptides and then to amino acids by luminal enzymes Pathway 2 = Luminal enzymes digest proteins to peptides, and then enzymes at the brush border digest peptides to amino acids Pathway 3 = Luminal enzymes digest proteins to peptides, which are taken up as oligopeptides by enterocytes</p> Signup and view all the answers

    How are absorbed protein products primarily transported into the blood?

    <p>As individual amino acids</p> Signup and view all the answers

    Amino acids are only absorbed through the apical membrane.

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

    What is the characteristic that distinguishes lipids from other biomolecules?

    <p>preferential solubility in organic solvents</p> Signup and view all the answers

    At least ______________ distinct amino acid transport systems are present at the apical membrane.

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

    Match the following membrane transporters with their functions:

    <p>Apical membrane transporters = Uptake of amino acids from the lumen Basolateral membrane transporters = Exit of amino acids into the blood and uptake from the blood for cell nutrition</p> Signup and view all the answers

    What is essential to build rapport with obese patients?

    <p>Compassion and understanding coupled with flexible and practical weight loss recommendations</p> Signup and view all the answers

    Most patients who seek medical care have a BMI of 38 or more.

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

    What should be the initial step in the clinical evaluation of the obese patient?

    <p>Proper assessment of the barriers to, and benefits of, weight loss</p> Signup and view all the answers

    Establishing where the patient is located on the _______________________ can be useful in helping to approach and commence your treatment plan.

    <p>Stages of Change Model</p> Signup and view all the answers

    Match the following stages with the corresponding descriptions:

    <p>Precontemplators = Patients who are not intending to lose weight Contemplators = Patients who are considering losing weight Preparers = Patients who are preparing to lose weight Actors = Patients who are actively losing weight</p> Signup and view all the answers

    Obesity and its common comorbidities are often silent.

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

    What is a characteristic of obesity?

    <p>It is a chronic illness with co-morbidities</p> Signup and view all the answers

    According to the WHO, obesity has decreased worldwide since 1975.

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

    What is the estimated number of people who were either overweight or obese in 2016?

    <p>at least 2.5 billion</p> Signup and view all the answers

    Exercise and dietary changes are the main contributors to ______________.

    <p>significant weight loss</p> Signup and view all the answers

    Match the following statements with their corresponding effects:

    <p>Obesity = Associated with disease and disability Overweight and obesity = Causes more death than being underweight Significant weight loss = Often controls or eliminates comorbidities</p> Signup and view all the answers

    Obesity is often viewed as a moral or social issue.

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

    What is a long-term outcome of obesity management?

    <p>Rare success without ongoing medical efforts</p> Signup and view all the answers

    What is the foundation of a behavioural-based approach to the management of obesity?

    <p>Exercise, diet modifications, and lifestyle changes</p> Signup and view all the answers

    Obesity reduces life expectancy, and this effect is more powerful in those who develop obesity earlier in life.

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

    What is the implication of obesity on life expectancy?

    <p>Life expectancy decreases by about 7 years compared with normal-weight individuals.</p> Signup and view all the answers

    In Australia, per capita spending is approximately $_____________ more for an obese individual versus someone of normal body weight.

    <p>830</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Overweight = An excess of subcutaneous fat in proportion to lean body mass Obesity = An abnormal or excessive fat accumulation that presents a risk to health Body Mass Index (BMI) = Indicates overweight for height, but does not discriminate between fat mass and lean tissue</p> Signup and view all the answers

    A long-term-horizon approach is imperative to success in the management of obesity.

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

    What is the best measure of visceral fat?

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

    Leptin is secreted by fat cells, not muscle cells.

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

    What is the significance of a sagittal diameter greater than 30cm?

    <p>An increase in cardiovascular disease risk and insulin resistance</p> Signup and view all the answers

    According to the Set-Point Theory, weight loss decreases total and resting energy expenditure by approximately _________%.

    <p>15</p> Signup and view all the answers

    Match the following with their effects on energy expenditure:

    <p>Weight loss = Decreases energy expenditure Weight gain = Increases energy expenditure Resting metabolic activity = Accounts for about 70% of energy expenditure Metabolic cost of food digestion = Accounts for about 10% of energy expenditure</p> Signup and view all the answers

    Genetic factors are thought to be a factor in at least half of human obesity, based on studies of twins raised separately or children who were adopted.

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

    Approximately how many kcal are needed to lose 1kg of weight?

    <p>7700 kcal</p> Signup and view all the answers

    Higher-protein diets tend to reduce satiety.

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

    What is the recommended daily calorie intake for weight maintenance, even for those at bed rest?

    <p>1200 kcal</p> Signup and view all the answers

    The calorie content of fat per gram is approximately _______________________ kcal.

    <p>9</p> Signup and view all the answers

    What is the primary purpose of exercise testing in overweight or obese individuals?

    <p>To assess for the presence of coronary artery disease</p> Signup and view all the answers

    International guidelines recommend a 20% weight loss within 4-6 months as an initial weight loss goal.

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

    What is the essential first step in diet therapy to lower weight?

    <p>calorie reduction</p> Signup and view all the answers

    For normal adults, ______________ kcal/kg is required daily to maintain weight.

    <p>22</p> Signup and view all the answers

    Match the following modes of exercise with their characteristics:

    <p>Walking = Preferred mode of exercise for testing Seated devices (e.g. upper body ergometers) = Non-weight-bearing mode Recumbent stepping machines = Non-weight-bearing mode</p> Signup and view all the answers

    What is the estimated weight loss in completers in trials of up to one year?

    <p>4-5% of baseline weight</p> Signup and view all the answers

    Surgical therapy is typically restricted to those with a BMI ≥ 30.

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

    What is the recommended amount of exercise per week for weight loss maintenance?

    <p>60-90 minutes</p> Signup and view all the answers

    Newer laparoscopic techniques can cause patients to lose _______ of their weight within 18 months.

    <p>one third</p> Signup and view all the answers

    Match the following exercise types with their descriptions:

    <p>Cardiorespiratory Exercise = Aerobic exercise for weight loss Exercise for Weight Gain Prevention = Exercise required to prevent weight gain Exercise Alone for Weight Loss = High amounts of total caloric expenditure required to lose weight by exercise alone</p> Signup and view all the answers

    Why is aerobic exercise preferred over resistance training for weight loss?

    <p>Aerobic exercise is linked to reductions in body mass</p> Signup and view all the answers

    Individuals who are obese and hypertensive may be taking a beta blocker.

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

    What is the goal intensity for individuals who have exercised previously?

    <p>60-80% HRR</p> Signup and view all the answers

    Behavioural changes in activity must be ______________________ and long lasting if the patient is to lose weight and maintain weight loss over the long term.

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

    Match the following exercise frequencies with their descriptions:

    <p>Daily = Ideal goal for exercise frequency 2-3 days/week = Common frequency for resistance training Alternate days = May help reduce the risk of injury or allow mode-specific pain to subside</p> Signup and view all the answers

    What is the purpose of laboratory testing in the diagnosis of overweight and obesity?

    <p>To screen for comorbidities such as diabetes and hypothyroidism</p> Signup and view all the answers

    ECG is always necessary in the diagnosis of overweight and obesity.

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

    What is the purpose of comprehensive chemistry profiles in the diagnosis of overweight and obesity?

    <p>To screen for non-alcoholic fatty liver and renal disease</p> Signup and view all the answers

    The American College of Sports Medicine (ACSM) recommends that exercise testing is often not necessary for those beginning a ______________ exercise program.

    <p>low- to moderate-intensity</p> Signup and view all the answers

    Match the following diagnostic tests with their corresponding purposes:

    <p>Fasting BGL +/- OGTT = To diagnose diabetes Lipid profile = To evaluate cardiovascular health TSH and free T4 = To diagnose hypothyroidism ECG = To evaluate cardiovascular problems</p> Signup and view all the answers

    What is the function of lipoproteins in the body?

    <p>To transport cholesterol and triglycerides in the blood</p> Signup and view all the answers

    Dyslipidaemic patients have a reduced risk of CVD.

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

    What is the term for abnormal lipid levels in the blood?

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

    Lipids are necessary for _______________________ body functioning.

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

    Match the following terms with their definitions:

    <p>Lipids = A type of protein Cholesterol = A type of carbohydrate Triglycerides = Major carriers of energy-containing fatty acids Lipoproteins = A type of hormone</p> Signup and view all the answers

    How long do HDLc levels last after exercise before returning to pre-exercise levels?

    <p>72 hours</p> Signup and view all the answers

    The exercise effect on serum triglyceride is lost after 24 hours regardless of the mode or intensity.

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

    What is the minimum caloric expenditure threshold needed to elevate HDLc in deconditioned individuals?

    <p>350 kcal</p> Signup and view all the answers

    A single session of endurance exercise lowers blood _______________________ concentrations.

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

    Match the following statements with their corresponding effects on HDLc and triglyceride levels:

    <p>A single session of endurance exercise = lowers blood triglyceride concentrations Exercise energy expenditure of 350 kcal = elevates HDLc in deconditioned individuals Exercise energy expenditure of 800 kcal = elevates HDLc in well-conditioned individuals 72 hours after exercise = HDLc levels return to pre-exercise levels</p> Signup and view all the answers

    What is the term used to describe abnormal lipid concentrations that may be high, but it can also refer to low levels of cholesterol associated with lipoproteins that are mostly cardioprotective in nature?

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

    The relationship between triglyceride concentrations and the incidence of CVD is a well-established fact with no ongoing debate.

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

    What is the primary function of HDL in the reverse cholesterol transport process?

    <p>HDL moves cholesterol from peripheral tissue to the liver for catabolism.</p> Signup and view all the answers

    Elevated postprandial lipaemia (PPL) may initiate many harmful events associated with _______________________ and arterial plaque build-up.

    <p>endothelial dysfunction</p> Signup and view all the answers

    Match the following lipoproteins with their primary functions:

    <p>LDL = Delivering lipids to extrahepatic tissue HDL = Eliminating cholesterol from peripheral tissue</p> Signup and view all the answers

    How many days of leisure-time physical activity are required for most people to meet the dose recommendations?

    <p>5 days</p> Signup and view all the answers

    Resistance training alone can significantly improve blood lipid and lipoprotein concentrations.

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

    What type of exercise provides no known benefit to lipid or lipoprotein profiles?

    <p>Range of Motion (ROM) exercise</p> Signup and view all the answers

    Patients should inform their AEP whenever their ______ are changed, or the dosages are increased.

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

    Match the following statements with their corresponding exercise types:

    <p>Accumulate 150 to 300 minutes of moderate-intensity exercise throughout the week = Cardiorespiratory Exercise Provides no known benefit to lipid or lipoprotein profiles = Range of Motion Exercise May have limited effect on improving blood lipid and lipoprotein concentrations = Resistance Exercise</p> Signup and view all the answers

    What is the preferred type of exercise for improving lipid status?

    <p>Cardiorespiratory exercise</p> Signup and view all the answers

    Does physical activity directly affect the metabolism of all lipids and lipoproteins?

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

    What is the recommended amount of moderate-intensity physical activity per week?

    <p>300 minutes</p> Signup and view all the answers

    Lipid and lipoprotein concentrations change the most __________ days after a single session of exercise.

    <p>1 or 2</p> Signup and view all the answers

    Match the following descriptions with the correct type of exercise:

    <p>Improves lipid status = Cardiorespiratory exercise Increases muscle mass = Resistance training Improves flexibility = Yoga</p> Signup and view all the answers

    What is another name for metabolic syndrome?

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

    The definition of metabolic syndrome includes compulsory factors such as insulin resistance and abdominal obesity.

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

    What are the health risks associated with metabolic syndrome?

    <p>Atherosclerotic cardiovascular disease and type 2 diabetes</p> Signup and view all the answers

    A diagnosis of metabolic syndrome requires the presence of any ______ or more abnormal findings.

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

    Match the following terms with their descriptions:

    <p>Metabolic syndrome = A collection of inter-related cardiometabolic risk factors. Syndrome x = Another name for metabolic syndrome. Dysmetabolic syndrome = Another name for metabolic syndrome.</p> Signup and view all the answers

    What is the main driver of metabolic syndrome?

    <p>Overweight and obesity</p> Signup and view all the answers

    Abdominal obesity is more common in women than men.

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

    What is the prevalence of metabolic syndrome in older adults (> 60 years)?

    <p>50%</p> Signup and view all the answers

    The metabolically healthy obese phenotype is characterised by high body mass index (BMI) yet subclinical (ie.normal) _______________________ health.

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

    Match the following waist circumference values with the corresponding abdominal obesity definitions:

    <p>≥ 88cm = Abdominal obesity definition for women ≥ 102cm = Abdominal obesity definition for men</p> Signup and view all the answers

    What is considered an independent risk factor for insulin resistance, hyperglycaemia, hypercholesterolaemia, and hypertension?

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

    Insulin resistance is a direct cause of the metabolic syndrome.

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

    What is the primary effect of insulin on glucose homeostasis in a healthy, insulin-sensitive person?

    <p>Insulin reduces plasma glucose concentration through suppression of hepatic glycogenolysis and gluconeogenesis and simultaneous glucose uptake, utilisation, and storage by the liver, muscle, and adipose tissue.</p> Signup and view all the answers

    Systemic inflammation, oxidative stress, and endothelial dysfunction are linked to the development of the _________.

    <p>metabolic syndrome</p> Signup and view all the answers

    What is the consequence of abnormal fat distribution and partitioning in obese individuals?

    <p>Increased risk of chronic disease</p> Signup and view all the answers

    Sedentary behavior is a robust predictor of improved mitochondrial function.

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

    What is the role of adipose tissue in insulin resistance?

    <p>Adipose tissue is considered a dynamic organ that secretes proinflammatory cytokines, contributing to insulin resistance.</p> Signup and view all the answers

    Impaired mitochondrial function may lead to decreased production of ______________ and energy deficit.

    <p>adenosine triphosphate (ATP)</p> Signup and view all the answers

    Match the following mitochondrial changes with their consequences in obese individuals:

    <p>Reduced mitochondrial size and density = Impaired insulin signaling Impaired mitochondrial function = Decreased ATP production Increased mitochondrial size and density = Improved insulin sensitivity Normal mitochondrial function = No effect on insulin sensitivity</p> Signup and view all the answers

    What is the suggested relationship between cardiorespiratory exercise and cardiometabolic health risk reduction?

    <p>The association between cardiorespiratory exercise and cardiometabolic health risk reduction is dose-dependent.</p> Signup and view all the answers

    Resistance exercise is effective for promoting clinically significant weight loss.

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

    What is the primary benefit of combining diet-induced energy restriction with resistance training?

    <p>Preventing loss of muscle tissue</p> Signup and view all the answers

    The diagnosis of the metabolic syndrome requires the presence of three or more of the following risk factors, including _______________________.

    <p>elevated waist circumference</p> Signup and view all the answers

    Match the following types of exercise with their benefits:

    <p>Cardiorespiratory exercise = Improving blood pressure and lipid profiles Resistance exercise = Enhancing fatty acid oxidation Range of Motion exercise = Decreasing visceral adiposity Combined aerobic and resistance exercise = Attenuating the proinflammatory state</p> Signup and view all the answers

    Study Notes

    Organisation of the Gastrointestinal System

    • The gastrointestinal tract is a tube that is specialised along its length for sequential processing of food.
    • It consists of a series of hollow organs (from mouth to anus) and accessory glands and organs that add secretions to the hollow organs.
    • Each hollow organ serves a specialised function, and they are separated at key locations by sphincters.

    Mouth and Oropharynx

    • The mouth and oropharynx are responsible for mechanical breakdown and lubrication of food.
    • They propel food into the oesophagus and initiate fat and carbohydrate metabolism.

    Oesophagus

    • The oesophagus is a conduit to the stomach.

    Stomach

    • The stomach is responsible for temporary food storage and churns and secretes proteases and acid that facilitate digestion.

    Small Intestine

    • The small intestine continues digestion and is the primary site for nutrient absorption.

    Large Intestine

    • The large intestine reabsorbs fluids and electrolytes (but not nutrient absorption) and stores faecal matter before expulsion.

    Accessory Glands

    • Accessory glands include salivary glands, pancreas, and liver.
    • The pancreas secretes digestive enzymes, bicarbonate to neutralise gastric acid, and secretes into the duodenum via the major and minor duodenal papilla.
    • The liver secretes bile (stored in the gallbladder between meals) and bile acids within bile, which are secreted at meal times, play a key role in fat digestion.

    Nutrient Digestion and Absorption

    • Digestion is the enzymatic conversion of complex dietary substances to a form that can be absorbed.
    • Most, but not all, digestive processes occur in the small intestine.
    • Absorption is the process of taking up nutrients into cells or across tissues and organs through diffusion or osmosis.

    Carbohydrate Digestion

    • Carbohydrates are classified into three major groups: monosaccharides, disaccharides, and polysaccharides.
    • The small intestine can directly absorb monosaccharides, but not polymers.
    • Carbohydrates require hydrolysis to monosaccharides before absorption.
    • Some polymers are digestible, while others are not.
    • Non-digestible polymers are fibre.
    • Dietary fibre is non-digestible polymers found in fruits, vegetables, and cereals.
    • Glycogen is the storage form of carbohydrate in animals.

    Carbohydrate Digestion Steps

    • Digestion of carbohydrates involves two steps: intraluminal hydrolysis and membrane digestion.
    • Intraluminal hydrolysis involves starch to oligosaccharides by salivary and pancreatic enzymes.
    • Membrane digestion involves hydrolysis of oligosaccharides to monosaccharides by brush border disaccharidases.

    Carbohydrate Absorption

    • The three monosaccharide products of carbohydrate digestion (glucose, galactose, and fructose) are absorbed by the small intestine in a two-step process.
    • The two steps involve uptake across the apical membrane into the epithelial cell and coordinated exit across the basolateral membrane.
    • The sodium/glucose transporter 1 (SGLT1) is responsible for glucose and galactose uptake at the apical membrane.
    • Fructose absorption occurs by the facilitated diffusion of fructose through GLUT5.
    • The exit of all three monosaccharides across the basolateral membrane uses the facilitated sugar transporter, GLUT2.

    Protein Digestion

    • Proteins must be digested into their constituent oligopeptides and amino acids before being taken up by the enterocytes.
    • Digestion-absorption of proteins occurs through four major pathways.
    • Protein digestion involves luminal enzymes (proteases) from the stomach and pancreas that hydrolyse proteins to peptides and then to amino acids, which are then absorbed.

    Protein Absorption

    • Virtually all absorbed protein products exit the villous epithelial cell and enter the blood as individual amino acids.
    • Substantial amounts of protein are absorbed from the intestinal lumen, via a H+-driven cotransporter, as dipeptides, tripeptides, or tetrapeptides and are then hydrolysed to amino acids by intracellular peptidases.
    • The absorption of amino acids across the small intestine requires sequential movement across both the apical and basolateral membranes of the villous epithelial cell.

    Lipid Digestion

    • Lipids are typified by their preferential solubility in organic solvents, compared with water.
    • The biological fate of lipids depends critically on their chemical structure, as well as on their interactions with water and other lipids in aqueous body fluids.

    Overweight & Obesity

    • Obesity and extreme obesity are associated with an increased rate of death from all causes, particularly from cardiovascular disease.
    • Obesity and sedentary lifestyle is considered the second leading cause of preventable death in the USA, and may overtake tobacco abuse within the next decade.
    • For obese individuals, life expectancy decreases by about 7 years compared with normal-weight individuals.

    Overweight & Obesity in Australia – A Growing Problem

    • In Australia, per capita spending is approximately $830 more for an obese individual versus someone of normal body weight.
    • Obesity reduces life expectancy and this effect is more powerful in those who develop obesity earlier in life.
    • In 2016, life expectancy fell slightly for the first time, reflecting the effects of obesity-related chronic illness on society.

    Management of Obesity

    • Exercise, diet modifications, and lifestyle changes are the foundation of a behavioral-based approach to the management of obesity.
    • A long-term-horizon approach is imperative to success.
    • Using a behavior change approach is critical to managing obesity.

    Definition of Overweight & Obesity

    • Overweight and obesity: an abnormal or excessive fat accumulation that presents a risk to health.
    • Body Mass Index (BMI): indicates overweight for height, but does not discriminate between fat mass and lean tissue.
    • BMI is a significant correlation with total body fat and is an acceptable clinical measure of overweight and obesity.

    Clinical Considerations in Overweight & Obesity

    • Although medically significant obesity exists in most patients who seek medical care, only a minority present requesting medical help with weight reduction.
    • Compassion and understanding coupled with flexible and practical weight loss recommendations are essential to building rapport with obese patients.
    • Most individuals seeking professional help with weight loss have a BMI of 38 or more, and invariably they have attempted to lose weight several times in the past.

    Pathophysiology of Obesity

    • Obesity results from longstanding positive energy balance.
    • Average daily calorie intake has increased by over 200 kcal over the last several decades as food costs have fallen dramatically and as more calories are consumed outside the home.
    • Recent research has identified an ever-increasing number of genetic and physiologic factors pointing to a large array of neurological and peripheral endocrine messengers that influence food intake and nutrient utilisation and that regulate weight in a way that often frustrates patients' weight loss efforts.

    Leptin and Genetic Causes of Obesity

    • Leptin is secreted by fat cells.
    • Humans produce leptin in proportion to their weight and girth.
    • Genetic causes of obesity are a feature of rare disorders such as Prader-Willi syndrome, but are thought to be a factor in at least half of human obesity based on studies of twins raised separately or children who were adopted.

    Set-Point Theory

    • Weight loss decreases total and resting energy expenditure, which slows further weight loss.
    • Weight gain through overfeeding is associated with an increase in energy expenditure, which slows further weight gain.
    • After weight loss, individuals require 15% fewer calories to maintain their lower weight.
    • This tendency causes weight loss patients to return to higher weights unless they restrict calories over the long term or expend calories through greater physical activity.

    Diagnostic Testing

    • Laboratory testing by a GP screens for diabetes (fasting BGL +/- OGTT), lipid profile (total cholesterol, HDL, LDL +/- triglycerides), and clinical or subclinical hypothyroidism (thyroid-stimulating hormone (TSH) and free T4).
    • Comprehensive chemistry profiles can screen for non-alcoholic fatty liver and renal disease.
    • ECG is rarely necessary except to evaluate specific cardiovascular problems such as elevated blood pressure and palpitations.

    Exercise Testing

    • There are no specific obesity-related guidelines for exercise testing.
    • Routine exercise testing in the overweight and obese population is often not necessary, particularly for those beginning a low- to moderate-intensity exercise program.
    • Exercise testing may be performed to assess for the presence of coronary artery disease or determine functional capacity and develop an exercise prescription based on heart rate.
    • Seated devices such as upper body ergometers, stationary cycles, or recumbent stepping machines offer excellent alternatives to walking, allowing patients to achieve maximal exercise effort in a non-weight-bearing mode.

    Treatment

    • Treatment goals should consider both the medical benefits of modest (10%) weight loss and the patient's expectations.
    • International guidelines recommend a 10% weight loss within 4-6 months and weight loss maintenance as an initial weight loss goal due to associated health benefits.
    • Few commonly prescribed weight loss programs achieve average weight losses that match patients' expectations.

    Diet Therapy

    • To lose weight, energy balance must be negative, and calorie reduction is the essential first step.
    • 22 kcal/kg is required daily to maintain weight, but this can vary by 20% depending on individual energy expenditure.
    • A daily caloric intake of at least 1,200 kcal is required, even for those at bed rest.
    • Exercise and activity levels affect maintenance calorie levels by 25% or more, depending on the degree of physical activity.
    • A deficit of 7,700 kcal is needed to lose 1kg, so an appropriate diet can yield about 0.5kg of weight loss per week.

    Surgical Therapy

    • Surgical procedures, such as laparoscopic techniques, can cause patients to lose one-third of their weight (>50% of their excess weight) within 18 months.
    • Research has confirmed improved mortality rates with weight loss surgery, but there are significant risks (up to 1% for death and 15% for morbidity).
    • Patients undergoing bariatric surgery must commit to a lifelong program of restricted diet, lifestyle changes, vitamin supplementation, and follow-up testing to ensure safety.

    Exercise Prescription

    • Exercise for weight gain prevention: 150-200 minutes/week (1,200-2,000 kcal/week) is required.
    • Exercise alone for weight loss: high amounts of total caloric expenditure (>3,000 kcal/week) are required to lose weight by exercise without caloric intake reduction.
    • Exercise and caloric reduction for weight loss: along with caloric reduction, aerobic exercise increases the weekly rate of weight loss by approximately 1kg over caloric reduction alone.
    • Exercise for weight loss maintenance: regular exercise of 60-90 minutes on most days of the week is generally recommended for long-term weight loss maintenance.

    Cardiorespiratory Exercise

    • Cardiorespiratory exercise is the primary type linked to reductions in body mass.
    • Resistance training may provide added benefits, particularly with respect to body composition, but the caloric expenditure of resistance training is less than that of aerobic exercise.

    Exercise Frequency and Intensity

    • Behavioural changes in activity must be consistent and long-lasting for weight loss and maintenance.
    • Exercise frequency and intensity should be adjusted to minimize fatigue and muscle soreness, with a goal of 60-80% HRR.

    Lipids and Lipoproteins

    • Lipids are a variety of fats necessary for normal body functioning
    • Cholesterol is a lipid that is an essential component of cell membranes, bile acids, steroid hormones, and vitamin D
    • Triglycerides are major carriers of energy-containing fatty acids
    • Lipoproteins are lipid-protein complexes that transport cholesterol and triglycerides in the blood

    Hyperlipidaemia and Dyslipidaemia

    • Abnormal lipid levels, particularly of cholesterol, triglycerides, and lipoproteins, are modifiable CVD risk factors
    • Dyslipidaemic patients have an elevated risk of CVD
    • Hypercholesterolaemia and hypertriglyceridaemia represent unhealthily elevated plasma concentrations of cholesterol and triglycerides, respectively
    • Dyslipidaemia refers to abnormal lipid concentrations that may be high or low, and may be associated with lipoproteins that are cardioprotective in nature

    Lipoprotein Metabolic Pathways

    • Atherosclerotic disease processes originate in early childhood and continue to develop through the interactions of genes, modifiable and non-modifiable environmental exposures
    • Blood lipoproteins provide a system of transportation for the movement of lipids between the intestine, liver, and extrahepatic tissue
    • Important enzymes and transfer proteins facilitate these interactions, including lipoprotein lipase (LPL), hepatic lipase (HL), lecithin-cholesterol acyltransferase (LCAT), and cholesterol ester transfer protein (CETP)

    LDL Receptor Pathway

    • The LDL receptor pathway consists of a sequence of chemical steps designed for the delivery of lipids to extrahepatic tissue
    • Low-density lipoprotein particles are the primary cholesterol carriers and deliver LDLc to extrahepatic tissue where LDL receptors located on the cell's surface mediate its uptake

    Reverse Cholesterol Transport

    • Cholesterol is moved to the liver for catabolism by a process termed reverse cholesterol transport
    • This elimination of cholesterol from the peripheral tissue involves several processes, including a pathway using nascent HDL particles secreted by the liver
    • HDL may possess anti-oxidative, anti-inflammatory, and anti-thrombotic properties and may also contribute to vascular endothelial repair

    Postprandial Lipaemia

    • Generally, the time needed after a meal for blood triglyceride levels to return to fasting levels is 6-8 hours
    • Exaggerated or prolonged lipaemia is associated with increased CAD risk
    • Elevated postprandial lipaemia (PPL) may initiate many harmful events associated with endothelial dysfunction and arterial plaque build-up

    Clinical Considerations

    • Elevated LDLc proportionally increases one's risk for ASCVD
    • The most recent guidelines differ in recognizing traditional cut-points for managing blood lipids and pharmacological treatment
    • Abnormal cholesterol levels are defined as follows:
      • Total cholesterol ≥ 5.5 mmol/L
      • HDLc < 1.0 mmol/L (men) or < 1.3 mmol/L (women)
      • LDLc ≥ 3.5 mmol/L

    Exercise and Dyslipidaemia

    • Cardiorespiratory exercise is preferred for improving lipid status, although a yet-defined combination program may be optimal
    • There is a dose-response relationship between cardiorespiratory exercise and cholesterol outcomes
    • The lipid- and lipoprotein-related benefits of physical activity rely more on the total volume of activity performed than on the intensity of the activity
    • Physical activity can directly affect the metabolism of some lipids and lipoproteins, while alteration of others may depend on changes in body composition

    Metabolic Syndrome

    • The metabolic syndrome is a collection of inter-related cardiometabolic risk factors that occur together more frequently than expected by chance.
    • Individuals with metabolic syndrome are usually categorized as overweight or obese and have a higher risk of developing atherosclerotic cardiovascular disease (ASCVD) and type 2 diabetes.

    Definition and Classification

    • The metabolic syndrome has been referred to by various names, including Syndrome X, Dyslipidaemic Hypertension, The Deadly Quartet, Insulin Resistance Syndrome, Dysmetabolic Syndrome, and Plurimetabolic Syndrome.
    • The definition and classification of metabolic syndrome have been debated, but the newest definition recommends that a diagnosis require the presence of any three or more abnormal findings.

    Scope

    • The reported prevalence of metabolic syndrome varies widely depending on the criteria used for diagnosing the condition.
    • According to a recent study, nearly 35% of adults and 50% of older adults (>60 years) satisfied the criteria for metabolic syndrome.

    Normal-Weight Obesity

    • Abdominal obesity increases with age even more so than BMI-assessed obesity.
    • There is a well-documented association between obesity and metabolic syndrome, but there are exceptions.

    Insulin Resistance and Metabolic Syndrome

    • Gradual decreases in cardiometabolic health start to occur long before an individual reaches obesity or is diagnosed as insulin resistant.
    • Insulin resistance is characterized by a chronic failure of insulin to maintain glucose homeostasis.
    • Research continues to emerge that confirms a pathophysiologic link between insulin resistance, metabolic syndrome, and glucose intolerance, as well as with ASCVD.

    Obesity and Adiposity Distribution Abnormalities

    • Obesity is an independent risk factor for insulin resistance, hyperglycemia, hypercholesterolemia, and hypertension.
    • Abnormal fat distribution and partitioning may be the pathophysiologic link between obesity and metabolic syndrome.
    • Accumulation of fatty acids in non-adipose tissue depots is robustly associated with skeletal muscle insulin resistance.

    Mitochondrial Dysfunction

    • Concurrent with an increased storage of ectopic adiposity, reductions in mitochondrial size, density, and function have been implicated in the etiology of insulin resistance, metabolic syndrome, and diabetes.
    • Mitochondrial dysfunction may lead to or coincide with decreased or incomplete lipid oxidation and subsequent accumulation of lipid metabolites, impaired insulin signaling, metabolic inflexibility, and oxidative stress.

    Cardiorespiratory Exercise

    • The utility of cardiorespiratory exercise is suggested to be dose-dependent, with greater volumes of physical activity associated with greater cardiometabolic health risk reduction.
    • Improvements in metabolic disturbances are possible with exercise interventions independent of overall weight loss or changes in body composition.

    Resistance Exercise

    • Resistance exercise is effective for improving cardiometabolic health among at-risk, obese individuals, comparable to aerobic exercise.
    • Chronic resistance training has been traditionally regarded as an appropriate means to augment or preserve skeletal muscle tissue and thus improve 24-hour energy expenditure and decrease body fat in the long-term.

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    Related Documents

    Week 1 - Metabolic Physiology PDF
    Week 2 - Overweight and Obesity - Part 1 PDF
    Week 2 - Overweight and Obesity - Part 2 PDF
    Week 3 - Hyperlipidaemia and Dyslipidaemia PDF
    Week 4 - Metabolic Syndrome PDF

    Description

    This quiz covers the organisation of the gastrointestinal system, including the gastrointestinal tract and its various organs, in the context of exercise for metabolic and mental health conditions.

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