Obesity
Introduction
More Americans are overweight today than at any point in the country's history. You've probably seen the commercials and infomercials for diet products that promise weight loss over mere days to weeks. You may also know that for most individuals these "quick fix" diets do not work. However, there is hope -- with a little hard work, better eating habits, and possibly medication therapy, obesity is treatable.
What is it?
Obesity is another term for excess body fat. Normal body fat percentages range from 18%-23% in men and 25%-30% in women. Men with a body fat percentage greater than 25% and women with a body fat percentage greater than 30% are considered obese. Obesity occurs when intake of calories exceeds the daily caloric requirements. The National Institute of Health (NIH) classifies obesity as a chronic disease, which requires a lifelong effort.
Determining if an individual has excess body fat can be done by various methods. These methods include body density using underwater body weight, dual x-ray absorptiometry (DEXA), measuring skin-fold thickness, computed tomography (CT), and magnetic resonance imaging (MRI). The DEXA test and weighing an individual underwater are the most accurate methods, although they can be expensive, time consuming and are not always practical.
The two most common methods for measuring a person's excess body fat are "weight-for-height" tables and body mass index (BMI) measurement. The weight-for-height tables provide a range of acceptable weights for a person of a given height. There are many versions of these tables with different weight ranges, which limits their use. Because of variability of these tables, BMI has become the measurement of choice for many doctors and researchers. BMI is calculated using a mathematical formula that accounts for a person's height and weight. BMI is equal to a person's weight in kilograms (kg) divided by height in meters squared (BMI = kg/m2). To learn how to calculate your own BMI, click on the link at the bottom of this page.
For both men and women, the normal BMI is between 20 and 24.9. Individuals with a BMI of 25 to 29 are considered to be overweight. Individuals with a BMI of 30 or higher are considered to be obese.
Calculate Your BMI
Another way to measure BMI is by using the following mathematical calculation:
Step 1: Multiply your weight in pounds by 703
Example: 703 x 200 lb = 140,600
Step 2: Multiply your height in inches by your height in inches
Example: 63 in x 63 in = 3,969
Step 3: Divide the answer in Step 1 by the answer in Step 2 to get your BMI
Example: 140,600 / 3,969 = 35.4
BMI = 35.4
Like the weight-for-height tables, BMI measurement is not without limitations. BMI does not provide information on a person's percentage of body fat or the difference between excess fat and muscle (which also increases body weight). Although BMI is closely associated with measures of body fat for most adults between the ages of 19 and 70 years it may not be the most accurate measurement for bodybuilders or pregnant women. These are individuals who may be overweight, but may not be obese. If you have any questions or are unsure of how to calculate your BMI, be sure to speak with your doctor at your next appointment. What causes it? Obesity occurs when a person consumes more calories than they actually use. This imbalance differs from person to person and therefore the exact cause of obesity is thought to involve other factors as well. Genetic, environmental, psychological, and regulatory factors may all contribute in varying degrees to developing obesity.
Genetic Factors
Family studies have shown that there is a correlation between the body weight of parents and their children. Studies have also shown that individuals who were adopted have a body fat distribution that is highly correlated with their biological parents rather than their adopted parents. The role of genetics in the development of obesity varies from person to person.
Environmental Factors
Lifestyle changes have contributed to the rise of obesity around the world in developed countries. These changes include the increased availability of food, reduced physical activity, increased intake of high fat foods, and decreased consumption of fruits and vegetables. Unlike genetic factors, environmental factors can be changed. Changing eating habits and increasing levels of activity are techniques to aid in weight loss.
Psychological Factors
Responding to emotions such as boredom, sadness, and anger may influence eating habits. It has been reported that overweight individuals do not suffer from psychological disorders any more often than normal weight people, but overweight individuals are more likely to binge eat. During binge eating episodes, individuals eat compulsively and greedily, losing control over how much food they are consuming. These binge episodes decrease the likelihood of losing weight.
Regulatory Factors
There are various medical conditions that may cause obesity, including the following:
Who has it? The latest data from the National Center for Health Statistics show that 30 percent of U.S. adults 20 years of age and older?over 60 million people?are obese. More than 60% of Americans over the age of 20 years are considered overweight. Depending on sex, age, socioeconomic status and race, these numbers vary. Obesity is more common in females than males with the incidence in black women being 1.5 times that of white women. It is twice as common in individuals of lower socioeconomic status. The prevalence of overweight (BMI greater than or equal to 25) Americans has not significantly changed in the past forty years, but the prevalence of obesity (BMI greater than or equal to 30) during this same time period more than doubled from 13.3 to 30.9 percent. Body mass index (BMI) for adults is found by dividing a person?s weight in kilograms by height in meters squared [weight (kg) / height squared (m2)]. To calculate your BMI using pounds and inches, multiply your weight in pounds by 704.5, then divide the result by your height in inches, and divide that result by your height in inches a second time. Of growing concern, an epidemic of childhood obesity is occurring in the United States. The prevalence of the most severe cases of childhood obesity -- defined as a BMI for age over the 95th percentile -- has virtually doubled over the past 20 years, while the prevalence of standard cases (BMI for age over the 85th percentile) has increased by about 50%. Childhood obesity carries its own morbidity (Type 2 diabetes mellitus, historically considered an adult disease, is now the most common type of diabetes diagnosed in several pediatric diabetes centers) and mortality (there are reports of children between 6 and 10 years of age with a BMI over the 99th percentile who died of sudden cardiopulmonary arrest apparently caused by irregularities in heart rate associated with their obesity). Decreased physical activity levels, increased calorie intake because of the availability of fast-foods, and an increasing lack of adult supervision in the lives of many children are all contributing factors to obesity in children. What are the risk factors? Obesity can affect anyone -- there are no defined absolute risk factors. However, it is known that certain groups of people are more likely to become obese. Risk factors for becoming obese include the following:
Studies have shown that certain people are more prone to becoming obese. Groups with a greater risk for developing obesity include the following:
Along with risk factors for becoming obese, once a person is obese, they are at greater risk for developing chronic diseases and suffering from premature death. Common chronic diseases associated with obesity include the following:
The amount of excess fat an individual has is not the only concern when discussing obesity. Where the fat is located on the body is also a concern. Men and women tend to have varying patterns of fat distribution. Women often carry fat on their hips and buttocks, giving their figures a "pear" shape. Men often carry fat around the belly, giving them more of an "apple" shape. Individuals with an "apple" shape are more likely to develop health problems as a result of their obesity than "pear" shaped individuals. To determine whether an individual is an "apple" or a "pear," the waist-to-hip-ratio is calculated. This is calculated by dividing the waist circumference by the hip circumference. Men and women with a waist-to-hip ratio of 1.0 or higher are considered to be "at risk" for chronic health problems as a result of being overweight.
What are the symptoms? Symptoms of obesity are the consequences of excess tissue mass. Sleep apnea, obesity-hypoventilation syndrome (Pickwickian syndrome), and skin disorders are relatively common in obese patients.
Sleep apnea occurs when an individual temporarily stops breathing while sleeping. This can occur up to 100 times per night. The obesity-hypoventilation syndrome occurs when breathing is impaired leading to under-ventilation, flushed or red face, and drowsiness. This syndrome increases the risk for premature death. In addition, skin disorders may result from moisture being trapped in skin folds of obese patients, resulting in heat rash, inflammation, and certain infections.
Obesity may also cause fatigue and joint pain from supporting the excess body weight.
How is it treated? The FDA is calling the nation?s obesity problem an ?epidemic? and released a report in 2004 with goals and actions focusing on a campaign entitled, ?Calories Count.? Recommended actions include:
Obesity is associated with increased morbidity and mortality. Weight loss reduces risk factors for complications associated with the excess weight, including diabetes and cardiovascular diseases. There are several treatment options for the management of overweight and obese individuals, including diet therapy, changes in physical activity, behavioral therapy, drug therapy, surgery and a combination of these.
The initial goal of weight loss therapy is to decrease body weight by about 10%. Once this goal is met, then further weight loss can be attempted. This weight loss will not occur overnight, but you can see a difference over mere weeks if you stay with your program. Once the weight is lost, maintenance of the loss needs to be implemented to ensure that the weight stays off.
Diet Therapy
Lifestyle modifications such as increasing physical activity and decreasing calorie intake are recommended instead of "dieting." Crash diets should definitely be avoided. The best approach to changing your diet is to talk to your doctor to find out what is best for you. Your doctor can provide you with dietary guidelines or refer you to a dietician for further help. Dietary guidelines will differ for each person depending on height, weight, concurrent health conditions, and desired amount of weight loss. A diet must be established that will allow for weight loss and be easy to comply with. Maintenance of your program is the key to keeping the pounds off.
Exercising is important to any good weight loss program. An aerobic exercise program reduces weight regardless of any changes you make in your diet. Adding 45 minutes of aerobic exercise a day is the equivalent of losing 400-800 Calories depending on your intensity. Minimally, that would result in losing one pound per week. Even if you can only exercise three times per week, that would still help you lose almost 2 pounds per month or 20 pounds over a year! Remember that this is without any changes in your diet. Dropping 500 Calories a day from your diet (the equivalent of one large French fries) will double your results.
Weight training and calisthenics also help you to reduce weight not by direct loss but by decreasing fatty tissue and increasing lean body mass. This will increase your metabolism and burn more calories while at rest.
Obese patients should start slowly with low-intensity walking or swimming and advance intensity as tolerated. If you have cardiovascular disease or other conditions that may make exercise very difficult, talk to your physician before you begin.
Behavioral Therapy
Behavior modification is common to all weight loss programs. Modification includes strategies that aid individuals to overcome barriers to comply with dietary changes and physical activity. Most behavioral modification programs encourage self-monitoring of both diet and exercise to increase one's own awareness of the activities. Modification strategies may also include stress management, social support, and stimulus control.
Combining behavioral therapy, diet therapy, and increased physical activity should be considered as initial "therapy" for weight loss. This combination should be continued for at least 6 months before proceeding to drug therapy.
Drug Therapy
After all other modes of losing weight have failed, you should talk to your physician about your options with drug therapy. Drug therapy may be considered for some individuals as a supplement to a comprehensive weight loss program that also includes diet, exercise, and behavioral therapy. Medications can be used to stimulate weight loss by either decreasing the appetite or inhibiting the absorption of fat from the intestines. Also, certain antidepressants such as fluoxetine (Prozac) and sertraline (Zoloft) may suppress the appetite by regulating levels of serotonin, a neurotransmitter in the brain. Serotonin is thought to induce a feeling of hunger and fullness. Click on the links below to learn more about available prescription medications that can aid in weight loss.
Many health food and supplement stores promote various "natural" or herbal products for weight loss. Even though they claim to be effective and "natural," these products can be associated with certain harmful side effects. The U.S. Food and Drug Administration (FDA) has stringent rules pertaining to the safety, efficacy, and quality that pharmaceutical manufacturers must follow in order to market drugs in the U.S. Manufacturers of herbal supplements do not have to follow these same rules to sell their products. For this reason, there is limited research evaluating supplements' safety and efficacy in the human body. As a result, anyone who chooses to take these substances does so at their own risk.
The most important thing to remember is that weight loss takes time and effort, and is a lifelong process. Also, it is important to set reasonable goals. Sensible weight loss does not occur overnight and it takes major changes in your lifestyle before significant changes in weight may be observed. Permanent weight loss can be reached by continued lifestyle changes.
Helping Yourself The best way to lose weight successfully is to incorporate a combination of diet changes and exercise. Generally, reducing your daily caloric intake by 500 to 1,000 calories each day is a good start, although you should first talk to your doctor to find out what's most appropriate for you. For most women a general guideline for daily calorie intake is 1,000 to 1,200 calories and for most men is 1,200 to 1,600 calories. Fat calories should typically make up less than 30% of total calories in this diet.
You should also increase your physical activity to help in weight loss. Easy ways to do this include walking, swimming, taking the stairs instead of an elevator, and parking a little farther away from buildings when shopping or going to work. Walking is an easy and safe way to begin. Start by walking 30 minutes a day 3 times each week. Gradually increase this to 45 minutes a day on at least 5 days each week. This will not only increase your daily caloric expenditure by 100 to 200 calories, it will also help decrease your risk of other diseases such as diabetes mellitus and heart disease. Of course, you should always talk to your doctor before you begin an exercise regimen to be sure that the regimen is appropriate for you.
For more information on dietary guidelines, click on the following link:
Dietary Guidelines
What is on the horizon? Currently researchers are studying a new type of drug class called cannabinoid receptor antagonists. This type of drug would help decrease an individual's appetite. Rimonabant, which will be marketed as Acomplia, has the potential to become a major breakthrough in treating obesity. In four major clinical trials, Acomplia has been shown to help obese people lose weight, improve A1c level in diabetics -- a measure of blood sugar control, reduce cardiovascular risk factors, and stop smoking. The manufacturer has not said for which of these indications it is seeking approval.
The one-year results of a phase III trial were presented in 2005 to the American Diabetes Association (ADA). 1,045 people with type 2 diabetes took either rimonabant or a placebo. Participants in this trial had an average age of 56 years and an average (BMI) of 34. All participants in the trial were told to reduce their daily caloric intake by 600 calories.
Participants in this study on Acomplia lost an average of 11.7 lbs compared to 3 lbs for patients in the placebo group. In addition, patients treated with Acomplia saw a reduction in waist circumference of 2 inches versus 0.7 inches for those taking the placebo and a reduction in A1c of 0.6% versus an increase of 0.1%, respectively.
Acomplia also showed a beneficial effect on lipids. Among patients who entered the study, the good HDL-cholesterol increased by 15.4 percent in the group taking Acomplia dose versus 7.1 percent in the placebo group.
Researchers report that the results of all four studies have shown similar safety data with side effects that were mainly mild and temporary. The most experienced adverse effect was nausea, reported by 12.1 percent of patients on the Acomplia. Other common side effects included dizziness, diarrhea, hypoglycemia, and anxiety. Three percent of participants on the Acomplia dropped out of the study because of intolerable side effects compared to 1% of those on placebo.
One important note is that you have to stay on the drug to maintain the effects. It seems that if you stop the drug, the weight comes back. If approved by the FDA, post-market surveillance will play a major role in determining the efficacy of the drug. One member of the ADA said after the meeting, ?It's one thing to say that a drug is safe in 6,000 people tested in clinical trials, but we have to see what happens when 750,000 people are using the drug."
In addition to Acomplia, other drugs that could potentially treat obesity are currently being studied in humans. Axokine, a synthetic form of human ciliary neurotrophic factor (CNTF), has been linked to appetite suppression and weight loss in clinical trials. ATL-962, a drug being developed by British investigators, may help block fat absorption. And topiramate, a drug currently used to treat seizures in the U.S., has helped certain patients lose weight in clinical trials.
A non-prescription strength formulation of the obesity drug orlistat is also being studied in clinical trials. Currently available by prescription only, Xenical contains 120mg of orlistat. The non-prescription version of the drug, called Alli, would contain 60mg of orlistat. Studies have shown that this reduced strength of orlistat effectively promotes weight loss in obese patients when combined with a reduced-calorie diet. If over-the-counter status is accepted, Alli would be the only FDA-approved weight loss medication available to patients without a prescription.
Finally, research is ongoing to isolate the gene that leads to developing obesity. Researchers have successfully manipulated this gene in mice. However, the specific gene or genes responsible for obesity in humans is unknown. Many experts agree that more than one gene is likely involved in the development of human obesity. Therefore, while several drugs are showing promise, it is unlikely that a single drug will be found that can cure obesity.
References The Practical Guide Identification, Evaluation, and Treatment of Overweight and Obesity in Adults. NHLBI Obesity Education Initiative. Available at: http://www.nhlbi.nih.gov/guidelines/obesity/prctgd_c.pdf. Accessed January 2002.
National Institute of Diabetes and Digestive and Kidney Diseases. Weight-control Information Network. Understanding Adult Obesity. Available at: http://win.niddk.nih.gov/publications/understanding.htm. Updated March 2006. Accessed Oct 23, 2006.
National Institute of Diabetes and Digestive and Kidney Diseases. Weight-control Information Network. Prescription Medications for the Treatment of Obesity. Available at http://win.niddk.nih.gov/publications/prescription.htm. Updated Nov 2004. Accessed Oct 23, 2006.
MedicineNet. Obesity. Available at: http://www.focusondiabetes.com/script/main/art.asp?articlekey=943&rd=1.
Accessed Mar 1, 2002.
National Heart Lung and Blood Institute. Clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults: executive summary. Available at: http://www.nhlbi.nih.gov/guidelines/obesity/ob_home.htm. Accessed Mar 1, 2002.
Beers MH, Berkow R, eds. Obesity. In: The Merck manual of diagnosis and therapy. 17th ed. Whitehouse Station, NJ: Merck Research Laboratories; 1999.
St. Peter JV, Khan MA. Obesity. In: Pharmacotherapy: a pathophysiologic approach. 6th ed. Dipiro JT, Talbert RL, Yee CG, Matzke GR, Wells BG, Posey LM, eds. New York: McGraw-Hill; 2005.
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Flegal KM, Carroll MD, Ogden CL, Johnson CL. Prevalence and trends in obesity among US adults, 1999-2000. Journal of the American Medical Association. 2002;288:1723-1727.
Acomplia Report. Available at: http://www.acompliareport.com. Accessed Oct 23, 2006.
Alli Report. Available at: http://www.allireport.com/News/news-090806.htm. Accessed Oct 23, 2006.
Obesity Health Condition Last Updated: October 2006
Note: The above information is intended to supplement, not substitute for, the expertise and judgment of your physician, pharmacist, or other healthcare professional. It is not intended to diagnose a health condition, but it can be used as a guide to help you decide if you should seek professional treatment or to help you learn more about your condition once it has been diagnosed.