USF-COM Department of Family Medicine

Patient Education Information on... Index of Patient Education Topics

What Does "Obese"  Mean?

When doctors say that someone is "obese" or "overweight", they mean that this person weighs more than they should in order to be healthy.  More importantly, it means that they have too much body fat.  Fat is a normal part of the human body,  as it is a place where the body stores energy  within fat cells.  However, when  a person weighs 20% or more than  they should weigh,  they are considered overweight.  The way that many doctors decide if a person is overweight or obese is known as the body mass index (BMI), which is found using a person’s weight, measured in kilograms (1kilogram = 2.2 lb), and the person’s height measured in meters  (a meter is about 39 inches).  This measurement  helps the doctor decide if you have too much body fat.

An obese person will have a BMI of 27 or greater.   A person with a BMI of 20-25 is not obese,  and a BMI of 40 is severely obese. Doctors like the BMI because it helps separate people who are heavy because of increased muscle from those who are heavy because of increased fat. A person with a BMI of 27 or more is at increased risk for health problems like diabetes, heart disease and high blood pressure.  Skinfold measurements can also be used to measure body fat.  This is done by using a device which measures the thickness of fat on certain parts of the body like the wais t and back of the arm.  These measurements are used with a formula to determine body fat percentage.  Men  with more than 20% body fat and women with more than 30 % body fat are considered obese.

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Obesity is a common health problem

Obesity is one of the most common problems found at the family doctor’s office.  According to the National Institute of Health,  more than 1 out of every 3 Americans is overweight, and about one-half of women and one-fourth  of men are trying to lose weight using diet plans at any one time.   Last year, over 30 billion dollars was spent on diet and exercise products by Americans trying to lose weight.  However,  obesity is becoming more common in all types and ages of people, even young adults ages 25-44.

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Causes of Obesity

Since ancient times,  being overweight has been associated with  too much energy intake (through food) and too little energy used up (such as by exercising)  It is now known that obesity is caused by the combination of several  factors, including  genetics (inherited traits),  cultural  background, social and economic status, and psychological factors.  Each person has a different likelihood of becoming obese because each person is different.  People who are related to each other tend to have a similar chance of becoming obese.  Identical twins, who share the same inherited traits, are more likely to be similar in weight than non-identical twins .   Children who are adopted tend to be similar in weight to their biological parents when they grow up, not their adoptive parents.

Scientists who study how people eat have found that obese people both eat more food  than non-obese people, and eat more rapidly. The environment that a person lives in is also known to be important.  In some families,  poor food choices and lack of exercise lead to family members who become obese simply due to eating too many calories and not using enough through exercise.  In a small number of people, obesity results from medications or diseases, but this happens in only about 1 out of every 100 people who are obese.

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Problems Caused By Obesity

Being obese increases the risk of developing  serious health problems, including heart disease,   type II diabetes,  high blood pressure, and high cholesterol (which itself can lead to heart disease).  Obese people ages 20-44 have almost 4 times the risk of type II diabetes, over 5 times the risk of high blood pressure, and are twice as likely to have high blood pressure than adults of the same age who are not obese.  These conditions increase the risk of dying from heart attack and stroke.  In addition,  obesity increases the risk of some types of cancer,  such as cancers of the colon, rectum and prostate in men, and gallbladder, uterine,  breast, and ovarian cancers in women.

Carrying around too much body fat can have other effects on health and lifestyle as well.  Joints,  like the knees and ankles, can become diseased and wear out much more quickly than they normally would,  leading to osteoarthritis.  Pressure from body fat in the trunk of the body increases the chance of  problems with the lungs and digestive tract as well.  Problems such as sleep apnea (periods during sleep where a person stops breathing, then wakes up) and reflux (where acid from the stomach comes up from the stomach, causing burning and cough) happen often in obese people.  For women,  the increase in body fat causes larger amounts of estrogen in the body that can lead to menstrual irregularities, problems in pregnancy, and as previously mentioned, increased cancer risk.   Overall,  obese people may suffer job discrimination and have other social problems.
 

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Treatment of Obesisty

Treatment of obesity is based on making changes in lifestyle and behavior.   Most people who are obese can benefit from these types of changes which include following  a diet and exercise plan.  Because your doctor is most familiar with your health status, he or she should be consulted first before beginning any weight loss or exercise plan.  Your doctor can recommend the best way for you to lose body fat according to how much you need to lose, your age and fitness level, your overall health,  and your level of motivation.

A healthy diet for weight reduction should limit fat intake to less than 30% of total calories (20-25% is best), protein 15-20%, and carbohydrates 55-65% of total calories.
Since 3500 calories make up one pound of fat,  a dieting person must use up 3500 calories more than they take in to lose one pound.  Decreasing the amount of daily calories by 500 each day will allow you to lose one pound per week.  To determine the amount of calories you need each day, many weight loss plans use formulas or charts to figure out what you should weigh, called "ideal" or "desirable"  body weight.  Calories can be subtracted from this to help you lose weight. Following a healthy diet with a variety of foods,  balance between types of foods,  and gradual weight loss and changes in habits have shown to be effective over the long term.  Fad diets, such as eating only one type of food at a time, can cause health problems and usually result in weight gain after stopping the diet.  Changing eating habits will help maintain weight loss over the long term.

Exercise is important in treating obesity because it helps to maintain weight loss and protects lean muscle from being lost when you are trying to lose fat.  In addition, exercise has other benefits, such as improving your sense of well being, lowering appetite, and reducing high blood pressure.

Other treatments which have been used  for weight reduction include medications, both prescription and non-prescription, and surgery.   Medications prescribed for weight loss are either stimulants, which suppress appetite, or drugs which increase serotonin levels in the brain.  Non-prescription diet pills usually contain a mild appetite suppressant.  Doctors usually use medication only in very obese patients, but they are sometimes given to highly motivated patients who are not very overweight.  Surgical procedures, such as reducing the size of the stomach, are used only on very obese patients that have not been able to lose weight by other methods.

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Side Effects of Obesity Treatment

Treatment of obesity, like treatment of other medical conditions, can cause unwanted effects in some people.  Very low calorie diets (400-800 calories daily), for example, increase the risk of gallstones. In diets that do not have long term success, weight may be regained, so that health problems of obesity return.  This may result in a pattern of repeated dieting and weight gain. Although not proven, some experts believe this pattern may make it difficult to lose weight in the future.

If medications are used in weight loss, side effects such as dry mouth, stomach upset, nervousness and drowsiness or insomnia (difficulty falling asleep) may occur.  Surgical procedures can result in more serious problems such as infection, nausea and vomiting, and vitamin deficiency.  For these treatments to be used, the doctor and patient must agree that weight loss is important enough to accept these risks.

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Summary

There are many different programs to treat obesity, each has its own advantages and disadvantages.  Good nutrition, exercise, and motivation to lose weight are parts of any successful plan.  It is also important to learn to change eating behavior and to have social, emotional, and medical support from peer groups, family members, and your doctor.

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