Obesity and how it Affects the body
Facts about Obesity.
- Obesity means having excess body fat. For adults 35 and older, having a BMI greater than 30 is considered obese.
- Obesity is not just a cosmetic consideration. It is a chronic medical disease that can lead to diabetes, high blood pressure, heart disease, gallstones, and other chronic illnesses.
- Obesity has also been linked to increased risk for a number of cancers.
- Obesity is difficult to treat and has a high relapse rate. Most people who lose weight regain the weight within five years.
- Even though medications and diets can help, the treatment of obesity cannot be a short-term “fix” but has to be a lifelong commitment to proper diet habits, increased physical activity, and regular exercise.
- The goal of treatment should be to achieve and maintain a “healthier weight,” not necessarily an ideal weight.
- Even a modest weight loss of 5%-10% of initial weight and the long-term maintenance of that weight loss can bring significant health benefits by lowering blood pressure and lowering the risks of diabetes and heart disease.
- The chances of long-term successful weight loss are enhanced if the doctor works with a team of professionals, including dietitians, psychologists, and exercise professionals.
Weight Gain, Obesity & Cancer Risk
Excess weight is a known risk factor for many chronic diseases, such as diabetes and heart disease. Obesity can also be linked an increased risk for developing some cancers. To clarify the effects of weight gain on cancer risk, researchers in 2007 conducted an analysis of many studies reported in medical journals that describe 282,137 cases of cancer. The researchers wanted to see if weight gain had an effect on the risk for certain cancer types.
What is obesity?
- The definition of obesity varies depending on what one reads. In general, overweight and obesity indicate a weight greater than what is considered healthy. Obesity is a chronic condition defined by an excess amount of body fat. A certain amount of body fat is necessary for storing energy, heat insulation, shock absorption, and other functions.
- Obesity is best defined by using the body mass index. The body mass index is calculated using a person’s height and weight. The body mass index (BMI) equals a person’s weight in kilograms (kg) divided by their height in meters (m) squared. Since BMI describes body weight relative to height, it is strongly correlated with total body fat content in adults. An adult who has a BMI of 25-29.9 is considered overweight, and an adult who has a BMI over 30 is considered obese. A BMI of 18.5-24.9 is considered normal weight.
How common is obesity?
Obesity has reached epidemic proportions in the United States. Over two-thirds of adults are overweight or obese, and one in three Americans is obese. The prevalence of obesity in children has
increased markedly. Obesity has also been increasing rapidly throughout the world, and the incidence of obesity nearly doubled from 1991 to 1998.
What are the health risks associated with obesity?
Obesity is not just a cosmetic consideration; it is harmful to one’s health. In the United States, roughly 112,000 deaths per year are directly related to obesity, and most of these deaths are in patients with a BMI over 30. For patients with a BMI over 40, life expectancy is reduced significantly. Obesity also increases the risk of developing a number of chronic diseases, including the following:
Insulin resistance. Insulin is necessary for the transport of blood glucose (sugar) into the cells of muscle and fat (which is then used for energy). By transporting glucose into cells, insulin keeps the blood glucose levels in the normal range. Insulin resistance (IR) is the condition whereby the effectiveness of insulin in transporting glucose (sugar) into cells is diminished. Fat cells are more insulin resistant than muscle cells; therefore, one important cause of insulin resistance is obesity. The pancreas initially responds to insulin resistance by producing more insulin. As long as the pancreas can produce enough insulin to overcome this resistance, blood glucose levels remain normal. This insulin resistance state (characterized by normal blood glucose levels and high insulin levels) can last for years. Once the pancreas can no longer keep up with producing high levels of insulin, blood glucose levels begin to rise, resulting in type 2 diabetes, thus insulin resistance is a pre-diabetes condition.
Type 2 (adult-onset) diabetes. The risk of type 2 diabetes increases with the degree and duration of obesity. Type 2 diabetes is associated with central obesity; a person with central obesity has excess fat around his/her waist, so that the body is shaped like an apple.
- High blood pressure (hypertension). Hypertension is common among obese adults. A Norwegian study showed that weight gain tended to increase blood pressure in women more significantly than in men.
- High cholesterol (hypercholesterolemia)
- Stroke (cerebrovascular accident or CVA)
- Heart attack. A prospective study found that the risk of developing coronary artery disease increased three to four times in women who had a BMI greater than 29. A Finnish study showed that for every 1 kilogram (2.2 pounds) increase in body weight, the risk of death from coronary artery disease increased by 1%. In patients who have already had a heart attack, obesity is associated with an increased likelihood of a second heart attack.
- Congestive heart failure
- Cancer. Obesity has been linked to cancer of the colon in men and women, cancer of the rectum and prostate in men, and cancer of the gallbladder and uterus in women. Obesity may also be associated with breast cancer, particularly in postmenopausal women. Fat tissue is important in the production of estrogen, and prolonged exposure to high levels of estrogen increases the risk of breast cancer.
- Gout and gouty arthritis
- Osteoarthritis (degenerative arthritis) of the knees, hips, and the lower back
- Sleep apnoea
What causes obesity?
The balance between calorie intake and energy expenditure determines a person’s weight. If a person eats more calories than he or she burns (metabolizes), the person gains weight (the body will store the excess energy as fat). If a person eats fewer calories than he or she metabolizes, he or she will lose weight. Therefore, the most common causes of obesity are overeating and physical inactivity. Ultimately, body weight is the result of genetics, metabolism, environment, behaviour, and culture.
Genetics. A person is more likely to develop obesity if one or both parents are obese. Genetics also affect hormones involved in fat regulation. For example, one genetic cause of obesity is leptin deficiency. Leptin is a hormone produced in fat cells and also in the placenta. Leptin controls weight by signaling the brain to eat less when body fat stores are too high. If, for some reason, the body cannot produce enough leptin or leptin cannot signal the brain to eat less, this control is lost, and obesity occurs. The role of leptin replacement as a treatment for obesity is currently being explored.
Overeating. Overeating leads to weight gain, especially if the diet is high in fat. Foods high in fat or sugar (for example, fast food, fried food, and sweets) have high energy density (foods that have a lot of calories in a small amount of food). Epidemiologic studies have shown that diets high in fat contribute to weight gain.
A diet high in simple carbohydrates. The role of carbohydrates in weight gain is not clear. Carbohydrates increase blood glucose levels, which in turn stimulate insulin release by the pancreas, and insulin promotes the growth of fat tissue and can cause weight gain. Some scientists believe that simple carbohydrates (sugars, fructose, desserts, soft drinks, beer, wine, etc.) contribute to weight gain because they are more rapidly absorbed into the bloodstream than complex carbohydrates (pasta, brown rice, grains, vegetables, raw fruits, etc.) and thus cause a more pronounced insulin release after meals than complex carbohydrates. This higher insulin release, some scientists believe, contributes to weight gain.
Frequency of eating. The relationship between frequency of eating (how often you eat) and weight is somewhat controversial. There are many reports of overweight people eating less often than people with normal weight. Scientists have observed that people who eat small meals four or five times daily, have lower cholesterol levels and lower and/or more stable blood sugar levels than people who eat less frequently (two or three large meals daily). One possible explanation is that small frequent meals produce stable insulin levels, whereas large meals cause large spikes of insulin after meals.
Physical inactivity. Sedentary people burn fewer calories than people who are active. The National Health and Nutrition Examination Survey (NHANES) showed that physical inactivity was strongly correlated with weight gain in both sexes.
Medications. Medications associated with weight gain include certain antidepressants (medications used in treating depression), anticonvulsants (medications used in controlling seizures such as carbamazepine [Tegretol, Tegretol XR , Equetro, Carbatrol] and valproate [Depacon, Depakene]), some diabetes medications (medications used in lowering blood sugar such as insulin, sulfonylureas, and thiazolidinediones), certain hormones such as oral contraceptives, and most corticosteroids such as prednisone. Weight gain may also be seen with some high blood pressure medications and antihistamines. The reason for the weight gain with the medications differs for each medication. If this is a concern for you, you should discuss your medications with your physician rather than discontinuing the medication, as this could have serious effects.
Psychological factors. For some people, emotions influence eating habits. Many people eat excessively in response to emotions such as boredom, sadness, stress, or anger. While most overweight people have no more psychological disturbances than normal weight people, about 30% of the people who seek treatment for serious weight problems have difficulties with binge eating.
Diseases such as hypothyroidism, insulin resistance, polycystic ovary syndrome, and Cushing’s syndrome are also contributors to obesity.
Social issues: A link between social issues and obesity has been established. Lack of money to purchase healthy foods or lack of safe places to walk or exercise can increase the risk of obesity.
What are other factors associated with obesity?
Ethnicity. Ethnicity factors may influence the age of onset and the rapidity of weight gain. African-American women and Hispanic women tend to experience weight gain earlier in life than Caucasians and Asians, and age-adjusted obesity rates are higher in these groups. Non-Hispanic black men and Hispanic men have a higher obesity rate then non-Hispanic white men, but the difference in prevalence is significantly less than in women.
Childhood weight. A person’s weight during childhood, the teenage years, and early adulthood may also influence the development of adult obesity. For example, being mildly overweight in the early 20’s was linked to a substantial incidence of obesity by age 35; being overweight during older childhood is highly predictive of adult obesity, especially if a parent is also obese; being overweight during the teenage years is even a greater predictor of adult obesity.
Hormones. Women tend to gain weight especially during certain events such as pregnancy, menopause, and in some cases, with the use of oral contraceptives. However, with the availability of the lower-dose estrogen pills, weight gain has not been as great a risk.
How is body fat measured?
BMI is a calculated value and approximates the body’s fat percentage. Actually, measuring a person’s body fat percentage is not easy and is often inaccurate if the methods are not monitored carefully. The following methods require special equipment, trained personnel, can be costly, and some are only available in certain research facilities.
Underwater weighing (hydrostatic weighing): This method weighs a person underwater and then calculates lean body mass (muscle) and body fat. This method is one of the most accurate ones; however, it is generally done in special research facilities, and the equipment is costly.
BOD POD: The BOD POD is a computerized, egg-shaped chamber. Using the same whole-body measurement principle as hydrostatic weighing, the BOD POD measures a subject’s mass and volume, from which their whole-body density is determined. Using this data, body fat and lean muscle mass can then be calculated.
DEXA: Dual-energy X-ray absorptiometry (DEXA) is used to measure bone density. It uses X-rays to determine not only the percentage of body fat but also where and how much fat is located in the body.
What is the body mass index (BMI)?
The body mass index (BMI) is a now the measurement of choice for many physicians and researchers studying obesity.
The BMI uses a mathematical formula that accounts for both a person’s weight and height.
The BMI measurement, however, poses some of the same problems as the weight-for-height tables. Not everyone agrees on the cutoff points for “healthy” versus “unhealthy” BMI ranges. BMI also does not provide information on a person’s percentage of body fat. However, like the weight-for-height table, BMI is a useful general guideline and is a good estimator of body fat for most adults 19 and 70 years of age. However, it may not be an accurate measurement of body fat for bodybuilders, certain athletes, and pregnant women.
The BMI equals a person’s weight in kilograms divided by height in meters squared (BMI = kg/m2). To calculate the BMI using pounds, divide the weight in pounds by the height in inches squared and multiply the result by 703.
It is important to understand what “healthy weight” means. Healthy weight is defined as a body mass index (BMI) equal to or greater than 19 and less than 25 among all people 20 years of age or over. Generally, obesity is defined as a body mass index (BMI) equal to or greater than 30, which approximates 30 pounds of excess weight.
The World Health Organization uses a classification system using the BMI to define overweight and obesity.
- A BMI of 25 to 29.9 is defined as a “pre-obese.”
- A BMI of 30 to 34.99 is defined as “obese class I.”
- A BMI of 35 to 39.99 is defined as “obese class II.”
- A BMI of or greater than 40.00 is defined as “obese class III.”
Does it matter where body fat is located? (Is it worse to be an “apple” or a “pear”?)
- Concern is directed not only at how much fat a person has but also where that fat is located on the body. The pattern of body fat distribution tends to differ in men and women.
- In general, women collect fat in their hips and buttocks, giving their figures a “pear” shape. Men, on the other hand, usually collect fat around the belly, giving them more of an “apple” shape. (This is not a hard and fast rule; some men are pear-shaped and some women become apple-shaped, particularly after menopause.)
- Apple-shaped people whose fat is concentrated mostly in the abdomen are more likely to develop many of the health problems associated with obesity. They are at increased health risk because of their fat distribution. While obesity of any kind is a health risk, it is better to be a pear than an apple.
- In order to sort the types of fruit, doctors have developed a simple way to determine whether someone is an apple or a pear. The measurement is called waist-to-hip ratio. To find out a person’s waist-to-hip ratio measure the waist at its narrowest point, and then measure the hips at the widest point; divide the waist measurement by the hip measurement. For example, a woman with a 35-inch waist and 46-inch hips would have a waist-to-hip ratio of 0.76 (35 divided by 46 = 0.76).
- Women with waist-to-hip ratios of more than 0.8 and men with waist-to-hip ratios of more than 1.0 are “apples.”
- Another rough way of estimating the amount of a person’s abdominal fat is by measuring the waist circumference. Men with a waist circumference of 40 inches or greater and women with a waist circumference of 35 inches or greater are considered to have increased health risks related to obesity.
What can be done about obesity?
All too often, obesity prompts a strenuous diet in the hopes of reaching the “ideal body weight.” Some amount of weight loss may be accomplished, but the lost weight usually quickly returns. Most people who lose weight regain the weight within five years. It is clear that a more effective, long-lasting treatment for obesity must be found.
We need to learn more about the causes of obesity, and then we need to change the ways we treat it. When obesity is accepted as a chronic disease, it will be treated like other chronic diseases such as diabetes and high blood pressure. The treatment of obesity cannot be a short-term “fix” but has to be an ongoing lifelong process.
Obesity treatment must acknowledge that even modest weight loss can be beneficial. For example, a modest weight loss of 5%-10% of the initial weight, and long-term maintenance of that weight loss can bring significant health gains, including:
• lowered blood pressure;
• reduced blood levels of cholesterol;
• reduced risk of type 2 (adult-onset) diabetes (In the Nurses Health Study, women who lost 5 kilograms [11 pounds] of weight reduced their risk of diabetes by 50% or more.);
• decreased chance of stroke;
• decreased complications of heart disease;
• decreased overall mortality.
It is not necessary to achieve an “ideal weight” to derive health benefits from obesity treatment. Instead, the goal of treatment should be to reach and hold to a “healthier weight.” The emphasis of treatment should be to commit to the process of lifelong healthy living, including eating more wisely and increasing physical activity.
In sum, the goal in dealing with obesity is to achieve and maintain a “healthier weight.”
What is the role of physical activity and exercise in obesity?
The National Health and Examination Survey (NHANES I) showed that people who engage in limited recreational activity were more likely to gain weight than more active people. Other studies have shown that people who engage in regular strenuous activity gain less weight than sedentary people.
Physical activity and exercise help burn calories. The number of calories burned depends on the type, duration, and intensity of the activity. It also depends on the weight of the person. A 200-pound person will burn more calories running 1 mile than a 120-pound person, because the work of carrying those extra 80 pounds must be factored in. But exercise as a treatment for obesity is most effective when combined with a diet and weight-loss program. Exercise alone without dietary changes will have a limited effect on weight because one has to exercise a lot to simply lose 1 pound. However regular exercise is an important part of a healthy lifestyle to maintain a healthy weight for the long term. Another advantage of regular exercise as part of a weight-loss program is a greater loss of body fat versus lean muscle compared to those who diet alone.
Other benefits of exercise include:
• improved blood sugar control and increased insulin sensitivity (decreased insulin resistance),
• reduced triglyceride levels and increased “good” HDL cholesterol levels,
• lowered blood pressure,
• a reduction in abdominal fat,
• reduced risk of heart disease,
• release of endorphins that make people feel good.
Remember, these health benefits can occur independently (with or without) achieving weight loss. Before starting an exercise program, talk to a doctor about the type and intensity of the exercise program.
General exercise recommendations
Perform 20-30 minutes of moderate exercise five to seven days a week, preferably daily. Types of exercise include stationary bicycling, walking or jogging on a treadmill, stair climbing machines, jogging, and swimming.
Exercise can be broken up into smaller 10-minute sessions.
Start slowly and progress gradually to avoid injury, excessive soreness, or fatigue. Over time, build up to 30-60 minutes of moderate to vigorous exercise every day.
People are never too old to start exercising. Even frail, elderly individuals (70-90 years of age) can improve their strength and balance.
The following people should consult a doctor before vigorous exercise:
• Men over age 40 or women over age 50
• Individuals with heart or lung disease, asthma, arthritis, or osteoporosis
• Individuals who experience chest pressure or pain with exertion, or who develop fatigue or shortness of breath easily
• Individuals with conditions or lifestyle factors that increase their risk of developing coronary heart disease, such as high blood pressure, diabetes, cigarette smoking, high blood cholesterol, or having family members with early onset heart attacks and coronary heart disease
• A patient who is obese
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