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Obesity

Learn about the chronic condition of obesity and the various factors that contribute to its development. Understand the effects of excess weight on mortality and morbidity, including the impact of weight gain patterns, regional fat distribution, and a sedentary lifestyle.

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Obesity

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  1. Obesity And its Associated Risk Factors Pennington Biomedical Research Center Division of Education

  2. ObesityAn Overview • Overweight and obesity are both chronic conditions that are the result of an energy imbalance over a period of time. • The cause of this energy imbalance can be due to a combination of several different factors and varies from one person to another. • Individual behaviors, environmental factors, and genetics all contribute to the complexity of the obesity epidemic. 2009 CDC

  3. Energy ImbalanceWhat is it? • Energy balance can be compared to a scale. • An energy imbalance arises when the number of calories consumed is not equal to the number of calories used by the body. • Weight gain usually involves the combination of consuming too many calories and not expending enough through physical activity. Weight Gain Calories Consumed > Calories Used Weight Loss Calories Consumed < Calories Used No Weight Change Calories Consumed = Calories Used 2009 CDC

  4. Energy ImbalanceEffects in the Body • Excess energy is stored in fat cells, which enlarge or multiply. • Enlargement of fat cells is known as hypertrophy, whereas multiplication of fat cells is known as hyperplasia. • With time, excesses in energy storage lead to obesity. Fat cells 2009 J La State Med Soc .2005; 156 (1): S42-49.

  5. Fat Cell EnlargementHypertrophy • Enlarged fat cells produce the clinical problems associated with obesity, due to the following: • The weight or mass of the extra fat • The increased secretion of free fatty acids and peptides from enlarged fat cells. 2009 J La State Med Soc .2005; 156 (1): S42-49.

  6. Weight ClassificationsA Review • Body mass index (BMI) is a mathematical ratio which is calculated as weight (kg)/ height squared (m2). It is used to describe an individuals relative weight for height, and is significantly correlated with total body fat content. BMI is intended for those 20 years of age and older. • You can find tables on the web that have done the math and metric conversions for you. • http://www.pbrc.edu/Division_of_Education/Tools/BMI_Calculator.asp • or • http://www.nhlbisupport.com/bmi 2009 CDC

  7. Mortality and MorbidityAssociated with Obesity • The effects of excess weight on mortality and morbidity have been recognized for more than 2,000 years. It was Hippocrates who recognized that “sudden death is more common in those who are naturally fat than in the lean.” • Today, obesity is increasing rapidly. Research shows that many factors related to obesity influence mortality and morbidity. 2009 Endocrinol Metab Clin N Am. 2003; 32: 761-786.

  8. MortalityWeight, Fat Distribution, and Activity • The following factors have been shown to increase mortality in individuals: • Excess body weight • Regional fat distribution • Weight gain patterns • Sedentary Lifestyle 2009 Endocrinol Metab Clin N Am. 2003; 32: 761-786.

  9. MortalityExcess Body Weight • Mortality associated with excess body weight increases as the degree of obesity and overweight increases. • It is estimated that 280,000 to 325,000 deaths a year can be attributed to obesity in the United States, more than 80% of these deaths occur among individuals with a BMI greater than 30 kg/m2. 2009 Endocrinol Metab Clin N Am. 2003; 32: 761-786.

  10. MortalityRegional Fat Distribution • Regional fat distribution can contribute to mortality. • This was first noted in the beginning of the 20th century. • Obese individuals with an android (or apple) distribution of body fat are at a greater risk for diabetes and heart disease than were those with a gynoid distribution (pear). • Android fat distribution results in higher free fatty acid levels, higher glucose and insulin levels and reduced HDL levels. It also results in higher blood pressure and inflammatory markers. Android Gynoid 2009 Endocrinol Metab Clin N Am. 2003; 32: 761-786.

  11. MortalityWeight Gain • In addition to overweight and central fatness, the amount of weight gain after ages 18 to 20 also predicts mortality. • The Nurses’ Health Study and the Health Professionals Follow-up Study showed that a marked increase in mortality from heart disease is associated with increasing degrees of weight gain. 2009 Endocrinol Metab Clin N Am. 2003; 32: 761-786.

  12. MortalitySedentary Lifestyle • Sedentary lifestyle is another important component in the relationship of excess mortality to obesity. • A sedentary lifestyle increases the risk of death at all levels of BMI. • Unfit men in the BMI range of less than 25 kg/m2 had a significantly higher risk than men with a high level of cardiovascular fitness. • Obese men with a high level of fitness had risks of death that were not different from fit men with normal body fat. 2009 Endocrinol Metab Clin N Am. 2003; 32: 761-786.

  13. Morbidity Associated with Obesity • Overweight affects several diseases, although its degree of contribution varies from one disease to another. • Additionally, the risk of developing a disease often differs by ethnic group, and by gender within a given ethnic group. 2009 Endocrinol Metab Clin N Am. 2003; 32: 761-786.

  14. Obstructive sleep apnea Osteoarthritis Cardiovascular disorders Gastrointestinal disorders Metabolic disorders Endometrial, prostate and breast cancers Complications of pregnancy Menstrual irregularities Psychological disorders Morbidity Associated with Obesity Individuals who are obese are at a greater risk of developing: CDC 2009

  15. Cardiovascular DisordersAssociated with Obesity Hypertension Stroke Coronary Artery Disease Obese individuals are at a greater risk of developing these cardiovascular disorders: 2009

  16. Hypertension • Hypertension (HTN) is the term for high blood pressure. • Hypertension is identified when a blood pressure is sustained at ≥140/90 mmHg. • High blood pressure is referred to as the “silent killer,” since there are usually no symptoms with HTN. • Some individuals find out that they have high blood pressure when they have trouble with their heart, brain, or kidneys. 2009 NHLBI

  17. HypertensionThe Dangers • The heart to get larger, which may lead to heart failure. • Small bulges (aneurysms) to form in blood vessels. • Blood vessels in the kidney to narrow, which may lead to kidney failure. • Arteries in the body to harden faster, especially those in the heart, brain, kidneys, and legs. This can cause a heart attack, stroke, kidney failure, or can lead to amputation of part of the extremities. • Blood vessels in the eye to burst or bleed. This may cause vision changes and can result in blindness. Failure to find and treat HTN is serious, as untreated HTN can cause: 2009 NHLBI

  18. Hypertension • Blood pressure is often increased in overweight individuals. • Estimates suggest that control of overweight would eliminate 48% of the hypertension in Caucasians and 28% in African Americans. • Overweight and hypertension interact with cardiac function, leading to thickening of the ventricular wall and larger heart volume, and thus to a greater likelihood of cardiac failure. 2009 J La State Med Soc .2005; 157 (1): S42-49.

  19. Hypertension Prevalence in the Overweight 32.7 Age-adjusted prevalence of hypertension in overweight U.S. adults 27.0 27.7 22.1 14.9 15.2 Prevalence of HTN Adapted from: http://www.obesityinamerica.org/trends.html 2009

  20. Stroke • Normally, blood containing oxygen and nutrients is delivered to the brain, and carbon dioxide and cellular wastes are removed. • A stroke occurs when the blood supply to part of the brain is suddenly interrupted by a blocked vessel or when a blood vessel in the brain bursts. • Once their supply of oxygen and nutrients from the blood is cut off to the brain cells, they die. 2009 NINDS

  21. Stroke • Sudden numbness or weakness, especially on one side of the body • Sudden confusion or trouble speaking or understanding speech • Sudden trouble seeing in one or both eyes • Sudden trouble with walking, dizziness, or loss of balance or coordination • Sudden severe headache with no known cause The symptoms of a stroke include: 2009 NINDS

  22. Stroke • There are two forms of stroke: ischemic and hemorrhagic. • Ischemic stroke occurs when an artery to the brain is blocked. • Overweight and obesity increase the risk for ischemic stroke in men and women. • With increasing BMI, the risk of ischemic stroke increases progressively and is doubled in those with a BMI greater than 30 kg/m2 when compared to those having a BMI of less than 25 kg/m2. • Hemorrhagic strokes occur when a blood vessel in the brain erupts. • Overweight and obesity do not increase the risk for hemorrhagic strokes. NINDS 2009 J La State Med Soc .2005; 156 (1): S42-49.

  23. Coronary Artery Disease • Coronary artery disease (CAD) is a type of atherosclerosis that occurs when the arteries supplying blood to the heart muscle (coronary arteries) become hardened and narrowed. • This hardening and narrowing is caused by plaque buildup. • As the plaque increases in size, the insides of the coronary arteries get narrower, and eventually, blood flow to the heart muscle is reduced. • This is critical because blood carries much-needed oxygen to the heart. 2009 NHLBI

  24. Coronary ArteriesBlood Flow • When the heart muscle is not receiving the amount of oxygen that it needs, one of two things can happen: • Angina • Heart Attack Angina Thisis the chest pain or discomfort that occurs when the heart is not getting enough blood. Heart attack This is what happens when a blood clot develops at the site of the plaque in a coronary artery. The result is a sudden blockage, which may block all or most of the blood supply to the heart muscle. Because cells in the heart muscle begin to die when they are not receiving adequate amount of oxygen, permanent damage to the heart muscle can occur if blood flow is not quickly restored. 2009 NHLBI

  25. Coronary Artery Disease • Over time, CAD can weaken the heart muscle and contribute to: • Heart Failure • Arrhythmias Heart Failure In this condition, the heart can’t pump blood effectively to the rest of the body. Heart failure does not mean that the heart has stopped nor does it mean that it is about to. It means that the heart is failing to pump blood the way that it should. Arrhythmias Arrhytmias are changes in the normal beating rhythm of the heart. They can be either faster or slower than normal. Some arrhythmias can be quite serious. 2009 NHLBI

  26. Coronary Artery Disease • Obesity is associated with an increased risk for CAD. • Abdominal fat distribution is believed to be related as well. • Data from the Nurses Health Study illustrated that women in the lowest BMI but highest waist-to-hip circumference ratio had a greater risk of heart attack than those in the highest BMI but lowest waist-to-hip circumference ratio. • Regional fat distribution appears to have a greater effect on CAD risk than BMI alone. 2009 J La State Med Soc .2005; 156 (1): S42-49.

  27. Gastrointestinal DisordersAssociated with Obesity Colon Cancer Gall stones Obese individuals are at greater risk of developing these gastrointestinal disorders: 2009

  28. Colon Cancer • Colorectal cancer is a term used to refer to cancer that develops in the colon or the rectum. • The colon (a.k.a. the large intestine) is about 5 feet long and its role in the digestive system is to continue to absorb water and mineral nutrients from food. Once this process of absorption is complete, waste matter (feces) remains. • The rectum is the final 6 inches of the digestive system. Feces are passed from the large intestine to the rectum, to exit the body through the anus. 2009 American Cancer Society

  29. Colon Cancer • Colorectal cancer is the second leading cause of cancer-related deaths in the U.S. • It is estimated to cause about 55,170 deaths during 2006. 2009 American Cancer Society

  30. Colon CancerFindings Relating to Obesity • Colon cancer has been shown to occur more frequently in people who are obese than in people who are of a healthy weight. • An increased risk of colon cancer has been consistently reported for men with high BMIs. • Women with high BMI are not at increased risk of colon cancer. There is evidence that abdominal obesity may be important in colon cancer risk. 2009 NCI

  31. Gallbladder Disease • Cholelithiasis is the primary hepatobiliary pathology associated with overweight. • Cholelithiasis is a condition characterized by the presence or formation of gallstones in the gallbladder or bile ducts. • Normally, a balance of bile salts, lecithin, and cholesterol keep gallstones from forming. However, if there are abnormally high levels of bile salts or, more commonly, cholesterol, then stones can form. NIH 2009 J La State Med Soc .2005; 156 (1): S42-49.

  32. GallstonesFindings Related to Obesity • Obesity appears to be associated with the development of gallstones. • More cholesterol is produced at higher body fat levels. • Approximately 20 mg of additional cholesterol is synthesized for each kg of extra body fat. • High cholesterol concentrations relative to bile acids and phospholipids in bile increase the likelihood of precipitation of cholesterol gallstones in the gallbladder. 2009 Endocrinol Metab Clin N Am. 2003; 32: 761-786.

  33. GallstonesFindings Related to Obesity • In the Nurses’ Health Study, when compared to those having a BMI of 24 or less, • Women with a BMI > 30 kg/m2 had a 2-fold increased risk for symptomatic gallstones. • Women with a BMI > 45 kg/m2 had a 7-fold increased risk for symptomatic gallstones. • The relative increased risk of symptomatic gallstone development with increasing BMI appears to be less for men than for women. 2009 J La State Med Soc .2005; 157 (1): S42-49.

  34. GallstonesFindings Related to Obesity • Ironically, weight loss leads to an increased risk of gallstones-- because of the increased flux of cholesterol through the biliary system. • Diets with moderate levels of fat that trigger gallbladder contraction and subsequent emptying of the cholesterol content may reduce the risk of gallstone formation. • Bile acid supplementation can be used to lower ones risk for gallstone formation. 2009 J La State Med Soc .2005; 157 (1): S42-49.

  35. Metabolic DisordersAssociated with Obesity Diabetes Mellitus Dyslipidemia Liver Disease Obese individuals are at greater risk of developing these metabolic disorders: 2009

  36. Diabetes Mellitus • Type 2 diabetes mellitus (DM) is strongly associated with overweight and obesity in both genders and in all ethnic groups. • The risk for Type 2 DM increases with the degree and duration of overweight in individuals. • The risk for Type 2 DM also increases in individuals with a more central distribution of body fat (abdominal). 2009 J La State Med Soc .2005; 157 (1): S42-49.

  37. Obesity and Type 2 DMIn the United States Among people diagnosed with Type 2 diabetes, 55 percent have a BMI ≥ 30 (classified as obese), 30 percent have a BMI ≥ 25 or ≤30 (classified as overweight), and only 15 percent have a BMI ≤ 25 (classified as normal weight). 15% 55% 30% Adapted from: http://www.obesityinamerica.org/trends.html 2009

  38. Diabetes MellitusFindings Related to Obesity • The Nurses’ Health Study demonstrated the curvilinear relationship between increasing BMI and the risk of diabetes in women: • Women with a BMI below 22 kg/m2 had the lowest risk of DM • At a BMI of 35 kg/m2, the relative risk of DM increased 40-fold or 4,000% • The Health Professionals Follow-up Study demonstrated a similar relationship between increasing BMI and the risk of diabetes in men: • Men with a BMI below 24 kg/m2 had the lowest risk of DM • At a BMI of 35 kg/m2, the relative risk of DM increased 60-fold or 6,000% 2009 J La State Med Soc .2005; 157 (1): S42-49.

  39. Diabetes MellitusFindings Relating to Weightloss • Weight loss reduces the risk of developing diabetes. • In the Health Professionals Follow-up Study, a weight loss of 5-11 kg decreased the relative risk for developing diabetes by nearly 50%. • Type 2 DM was almost nonexistentwith a weight loss of more than 20 kg (44 lbs) or in those with a BMI below 20. 2009 J La State Med Soc .2005; 157 (1): S42-49.

  40. Dyslipidemia • Dyslipidemia is defined as abnormal concentration of lipids or lipoproteins in the blood. • As BMI increases, there is an increased risk for heart disease. • This is because a positive correlation between BMI and triglyceride (TG) levels has been demonstrated. 2009 Endocrinol Metab Clin N Am. 2003; 32: 761-786.

  41. DyslipidemiaFindings Related to Obesity • An inverse relationship between HDL cholesterol and BMI has been noted. • This relationship may be more important than the relationship between BMI & TG levels. • Low level of HDL carries more relative risk for developing heart disease than do elevated triglyceride levels. • Central fat distribution also plays an important role in lipid abnormalities. • Excessive body fat in the abdominal region leads to increased circulating triglyceride levels. HDL 2009 Endocrinol Metab Clin N Am. 2003; 32: 761-786.

  42. Liver Disease • Nonalcoholic fatty liver disease (NAFLD) is the term given to describe a collection of liver abnormalities that are associated with obesity. • In a cross-sectional analysis of liver biopsies of obese patients, it was found that the prevalence of steatosis, steatohepatitis, and cirrhosis were approximately 75%, 20%, and 2% respectively. 2009 J La State Med Soc .2005; 157 (1): S42-49.

  43. Liver DiseaseFatty Liver • Steatosis is the term for “fatty liver” and it is not actually a disease, but rather a pathological finding. • Most cases of fatty liver are due to obesity. • Other causes of fatty liver include: • Diabetes • Certain drugs • Intestinal bypass operations • Starvation • Protein malnutrition • Alcoholism The American Liver Foundation 2009

  44. Liver DiseaseFatty Liver • A gradual weight reduction can help to reduce the enlargement of the liver due to fat, and it can normalize the associated liver test abnormalities. • It is important to limit the amount of alcohol consumed in the diet. Alcohol can decrease the rate of metabolism and secretion of fat in the liver. 2009 The American Liver Foundation

  45. Importance of a Healthy Liver • The 300 billion cells of the liver control a process known as metabolism. During metabolism, the liver breaks down nutrients into usable products. These products are then delivered to the rest of the body through the bloodstream. • The liver also metabolizes toxins into byproducts that can be safely eliminated. • The liver also produces many important substances, such as: albumin, bile, cholesterol, clotting factors, globin, and immune factors. The liver is the largest organ in the body and it plays a vital role in performing many complex functions that are essential for life: 2009 Mayo Clinic

  46. Other DisordersAssociated with Obesity Obstructive sleep apnea Osteoarthritis Endometrial, prostate, and breast cancers Complications of pregnancy Menstrual irregularities Psychological disorders Obese individuals are at greater risk of developing these metabolic disorders: 2009

  47. Obstructive Sleep Apnea • Obstructive sleep apnea is caused by repetitive upper airway obstruction during sleep as a result of narrowing of the respiratory passages. • Patients having the disorder are most often overweight with associated peripharyngeal infiltration of fat and/or increased size of the soft palate and tongue. 2009 American Academy of Family Physicians

  48. Obstructive Sleep Apnea • Common complaints are loud snoring, disrupted sleep, and excessive daytime sleepiness. • Individuals with sleep apnea suffer from fragmented sleep and may develop cardiovascular abnormalities because of the repetitive cycles of snoring, airway collapse, and arousal. • Because many individuals are not aware of heavy snoring and nocturnal arousals, obstructive sleep apnea may remain undiagnosed. 2009 American Academy of Family Physicians

  49. Obstructive Sleep ApneaFindings Relating to Obesity • Obstructive sleep apnea affects around 4% of middle-aged adults. • Individuals having a BMI of at least 30 are at greatest risk for sleep apnea. • Weight loss has been shown to improve the symptoms relating to sleep apnea. 2009 J La State Med Soc .2005; 157 (1): S42-49.

  50. Osteoarthritis • Osteoarthritis (OA) is the most common type of arthritis • 40 million Americans currently have osteoarthritis. • It is a degenerative disease which frequently leads to chronic pain and disability. • For individuals over the age of 65, it is the most disabling disease. • Currently, only the symptoms of OA can be treated; there is no cure. 2009 NSLS

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