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Lecture

ObesityNotes.docx

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Department
Nursing
Course Code
NURSING 2LA2
Professor
Kirsten Culver

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Pathophysiology Module: Childhood Obesity Slide: Title – Nursing Concepts in Health & Illness Childhood Obesity  Prevalence of obesity is so high that the WHO and CDC now refer to the obesity epidemic.  The World Watch Institute released a report in the year 2000 stating for the first time in human history, the number of overweight people rivals the number of underweight people.  Even more concerning than the fact that 1/3 of US adults are considered obese, is that rates of childhood obesity have tripled since 1980 in the U.S.  This same trend is occurring globally.  According to the WHO 22 million children under the age of 5 are estimated to be overweight worldwide. Slide: Special Report in NEJM  A special report in the March 2005 edition of the New England Journal of Medicine warned that unless effective population level interventions to reduce obesity are developed, the steady rise in life expectancy observed in the modern era may soon come to an end and the youth of today may, on average, live less health and possibly even shorter lives than their parents.  This is frightening news considering we as a society are used to ever-lengthening life spans because of better living conditions and medical advances.  Now there is even talk of a double-cohort of cardiovascular patients.  Parents and their children could, in future, be vying for a limited number of hospital beds, similar to the way high school students competed for university acceptances in the 2003-2004 academic year. Slide: Canadian Statistics  I’ve already mentioned some of the global and U.S. statistics about childhood obesity, now we will talk about what is happening right here at home.  According to the childhood obesity foundation website, data from the most recent Canadian community health survey conducted in 2004 shows that 26% or 1.6 million Canadian children ages 2-17, are overweight or obese.  Many obese children and adolescents do not outgrow this condition.  Data from these studies show that obese children aged 10-13 have an 80% chance of becoming obese adults.  Many more children who are not overweight or obese will gain excess weight in adulthood.  Trends in weight gain forecast that approx. 1/3 of normal weight 20 year olds will become overweight within 8 years and approx. 1/3 of overweight 20 year olds will become obese within 8 years.  If this trend continues, in 20 years we can expect 70% of the 35-44 year olds in Canada to be overweight or obese vs. 57% who are currently overweight or obese.  The burden on the health care system due to obesity related illness will be enormous, which is why there is so much at stake in halting these trends now. Slide: Definitions  Overweight and obesity in adults is measured using body mass index.  A person’s weight in kilograms divided by the square of their height in meters squared.  The adult ideal for BMI lies between 18.5 and 24.9 kg/m . 2 2  Overweight is defined as 25-30 kg/m and over 30 kg/m is considered obese.  Because children grow at different rates based on age, ad because they also vary in growth patterns by gender, ideal weight is based on growth charts.  You will likely see a number of different measurement styles, but they will all be based on growth charts specific to a child’s age and gender.  The U.S. uses the CDC growth charts.  Plotting a child’s BMI on the growth chart appropriate for age and gender will allow you to see what percentile the child’s weight falls within.  Children with BMI’s beneath the 5 percentile are considered underweight, while those whose BMI falls on or between the 5 and 85 percentile, are at their ideal weight. th th  Children whose BMI is above the 85 but below theth5 percentile are overweight for their age.  Obesity is defined as a BMI at or above the 95 percentile for age and gender,  This year, the dieticians of Canada in cooperation with the Canadian Pediatric Society, the College of Family Physicians of Canada, and the Community Health Nurses of Canada recommended the adoption of the WHO growth charts as the gold standard for assessing growth in Canadian children.  These are thought to more accurately reflect growth in Canadian children and were created based on populations in a number of different countries.  The cut-offs for these charts are broken into three categories for children.  There are a set of parameters from birth to age 2, from ages 2-5, and ages 5-19 years. th  In this latter category, overweight is assessed as BMI for age abovththe 85 percentile specific for gender, while criteria for obesity is BMI for age above the 97 percentile and severe obesity is above the 99.9 percentile. Slide: Statistics Canada Data  In Canada, adolescents are the age group most affected by overweight and obesity.  From 1978/79 to 2004, the proportion of overweight children between 2 and 6 remained the same, although obesity, previously unseen in this age group, rose to 6% in this category in 2004.  Rates doubled in those in the 6-11 age group and again obesity appeared where it had not been seen before.  Obesity in the 12-17 age group tripled while the proportion of overweight to obese just over doubled since the previous measurement in 1978/79.  Some of the factors identified with obesity risk by the Canadian Community Health Survey were more than 2 hours of screen time per day, with TV viewing, computer time or video gaming and the consumption of less than 5 servings of fruits and vegetables per day. Slide: Causal Web  Obesity is caused by an imbalance between energy-in, in the form of intake of nutrient dense foods, and energy-out in the form of activity level.  This seems like a simple concept but there are many more factors involved, as illustrated by the complexity of this causal web.  There are many variables that dictate what the input/output ratios will look like.  Obesity is therefore not a simple problem with a single cause and there are no simple solutions.  Conditions in the family and home as well as availability of facilities for leisure time activities can have an impact.  Public transportation, safety and quality of health care can also contribute.  Education level may impact food and nutrition choices, regionally or nationally.  National perspective on education, health-care and nutrition can also complicate the picture.  Internationally, media and particularly food advertising are especially important for child nutrition.  As you can see, all of these factors are interconnected and create the complexity of factors that affect childhood obesity. Slide: Breaking News  One of he results of our busy lifestyles is the rise in consumption of fast food.  A study in the U.S. in 2004 established that of a population of adolescents and children over 5 years of age, 30% eat fast food each day.  That fast food meal adds an extra 187 calories which totals a whopping 6 lbs. of weight gain over the course of a year. Slide: Other Factors Involved  A previous slide showed the web of interrelated factors that can determine a child’s weight.  Ethnicity and genetics can also collude to cause obesity.  Certain populations are more susceptible to becoming obese which is why the proportion of obese individuals amongst First-Nations peoples and those of Hispanic and African descent are so high.  Adolescent males of Hispanic descent and adolescent African-American females appear to be especially predisposed to the development of obesity, given the right conditions.  Genetics plays its part in the development of obesity as well.  The biggest predictive factor in childhood obesity appears to be obesity in one or both parents.  It is more strongly correlated with maternal obesity but genetics are not the whole story.  Children obviously consume the same diet as their parents and have also been shown to mirror their activity level. Slide: Parents May Not Recognize the Problem  Studies have shown that parents may not recognize their child is overweight and may not be aware of the associated health consequences and the seriousness of the situation.  Since parents are responsible for food purchases and meal preparation, their lack of awareness may worsen the problem.  Parents have the greatest opportunity to makes the lifestyle changes necessary to ensure the health of their children.  But refusal to recognize the problem, may lead to continued weight gain over the remaining childhood years and maintenance of overweight or obese status into the adulthood.  Besides the risks to the child’s health, their quality of life may suffer due to the extra pounds.  When Dr. Jeffrey Schwimmer and his associates examined quality of life questionnaires from children and adolescents who were healthy and of normal weight, obese children, and pediatric cancer patients, they were surprised to find that the obese children scores were similar to those of the cancer patients. Slide: The Economist  This slide is a magazine cover from the year 2003.  The frightening thing about this is that we have evolved into humans over thousands of years yet it has only taken a few decades to develop into an overweight society.  In 2003, there were only 4 of the United States that had obesity levels over 25%.  The government statistics for 2008, the last year reported, show 19 states with obesity levels between 25-30% and 6 states with obese populations above 30%.  The Economist article talks about days gone by when the rich were fat and the poor were thin as opposed to today’s situation where the rich are thin and the poor are fat and there’s great concern over the epidemic of obesity that is sweeping the globe.  The authors blame evolution for designing us to store energy for lean times and since we have not experienced lean times in recent memory, our bodies continue to store the excess energy we take in and our waistlines continue to expand. Slide: Childhood Obesity Cartoon  This cartoon depicts another of the societal problems adding to the burden of childhood obesity.  Before the advent of personal computers and video games, children were far more active.  After school was a time to play ball in the park or hide-and-seek in your neighbourhood.  Now many children go home and play video games, watch TV, or use a personal computer for entertainment.  The problem with inactivity is compounded by the fact that playing video games or watching TV is often accompanied by snacking with high-fat calorie dense foods. Slide: The Trouble with FAT  Obesity can lead to poor self-esteem and in some cases depression.  But an additional and perhaps more serious health issue is the dysregulation of body systems leading to chronic illnesses.  Those who are obese are more likely to be diagnosed with cancer, liver disease, osteoarthritis, stroke, type II diabetes and any of a number of cardio-vascular diseases.  For years, adipose tissue, the main storage depot for triglycerides, which are the most common form of lipids consumed in a meal, was considered somewhat passive.  All that changed a little over a decade ago when it was discovered that adipose tissue synthesizes and secretes a number of substances including hormones and inflammatory molecules now referred to as adipokines.  These secreted substances allow different tissues in the body to interact to maintain lipid homeostasis.  However, constant overconsumption of food, especially high fat diets, causes dysregulation of this homeostasis and leads to the pathologies discussed in the different sections of this slide.  As you will learn in the following slide, this chronic exposure of tissues to high levels of lipids and their sometimes toxic metabolic byproducts is now considered to be the root cause of many of the health problems associated with obesity.  Stroke: o Obesity is a known risk factor for CV disease in general, but manifestation as ischemic stroke is less clear. o A recent study showed that, again, it is central obesity causes the greatest risk. o Chance of stroke was examined in the Northern Manhattan Stroke Study with respect to waist to hip ratio. o There was an association shown between ischemic stroke and waist-to-hip ratio even after correcting for confounding factors. o Greater waist-to-hip ratio increased the risk for ischemic stroke in both men and women although the risk was greater in men. o This effect seemed to be independent of the atherosclerotic risk factors, so there may some other mechanism involved in this association. o Risk of stroke from greater waist-to-hip ratio was shown at all ages but there appeared to be greater risk in those younger than 65. o Visceral adiposity (fat deposited around central organs) is associated with higher risk of stroke. o This effect was shown independent of CV risk factors. o Those younger than 65 had the greatest increase in risk from central obesity.  Type II Diabetes: o As will be explained further in the next slide, obesity may lead to type II diabetes over time. o First, due to dysregulated lipid metabolism, which then causes insulin resistance. o This insulin resistance may eventually lead to hyperglycemia, when the pancreas fails to be able to produce sufficient insulin to affect glucose uptake in cells. o Hyperglycemia, along with altered blood flow and vascular endothelial damage, may lead to diabetic retinopathy and eventual blindness. o Type II diabetes will be further explained in one of the other pathophysiology modules. o Insulin resistance is common in obesity, but can be reversed by lifestyle changes. o Hyperinsulinemia, due to resistance eventually leads to hyperglycemia and diabetes if not corrected. o Hyperglycemia and altered blood flow may lead to retinopathy and blindness.  Vascular Diseases: o Obesity and inactivity are two of the biggest risk factors in the development of atherosclerosis which can cause coronary artery disease as well as peripheral vascular disease. o The altered lipid metabolism results from a constant excess of nutrients as well as a diet high in fat leads to lower levels of HDL and higher levels of LDL and triglycerides. o The inflammatory process that is also a result of lipid dysregulation compounds the problem by increasing the influx of macrophages into vascular tissues where they remove LDL cholesterol from circulation creating foam cells and advancing the atherosclerotic process. o Dyslipidemia, common in obesity leads to atherosclerosis. o Inactivity compounds the problem. o Narrowed and less flexible vessels can lead to angina, myocardial infarction or stroke.  Liver Disease: o Over nutrition leads to the deposition of fat in liver cells. o This fat deposition is further enhanced by insulin resistance another consequence of constant overeating and inactivity. o There is increased risk of fatty liver disease amongst obese individuals and diabetes patients. o But it is present in almost everyone who is morbidly obese and diabetic. o Although those with fatty liver disease may start out asymptomatic, these fat deposits can lead to increases in inflammatory activity, fibrosis, and eventually cirrhosis in some cases. o Liver failure can result and the chances of hepatocellular carcinoma are increased as well. o Caused by fat deposition in liver cells. o Fat deposits increase inflammatory activity, causing fibrosis. o Present in virtually all who are morbidly obese AND diabetic.  Colon Cancer: o Obesity increases the risk of colon cancer, especially central obesity. o A high BMI was associated with increased risk of colon cancer, especially in men, among the Framingham Study cohort. o Waist circumference was even more strongly correlated with the chance of colon cancer and risk was found to increase linearly with increasing waist size in both men and women. o It seems that visceral adiposity or fat deposits around the central organs creates an even greater risk than elevated BMI alone. o High BMI is correlated with higher risk of colon cancer, especially in males. o Increasing waist circumference is linked to increased risk in men and women. o Apple shape (visceral or central adiposity) is associated with higher risk than pear shape (subcutaneous fat deposits, usually around hips and thighs).  Osteoarthritis: o Increased weight adds extra stress to bones and joints. o Osteoarthritis used to be associated with advanced age, but is now being seen at earlier ages, as is diabetes, another former disease of old age, especially in those with elevated BMIs. o In addition to the mechanical stress caused by excess weight, studies show that adipokines secreted by adipose tissue may have a role to play in causing and advancing osteoarthritis. o Investigation into inflammation related to adipokines was instigated with it was noticed that there was also an increase in osteoarthritis with high BMI in non-weight bearing joints, such as the hands. o Inflammatory cytokines, such as TNF-α, promote cartilage degradation and the advance of this disease. o Extra pounds add stress to bones and joints. o Joints not affected by mechanical stress (such as hands) are also affected in the obese. o Inflammatory molecules secreted by adipose tissue (adipokines) are likely responsible. Slide: Pathophysiology of Metabolic Syndrome  This slide examines the pathophysiological processes that underl
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