overweight and obesity
The terms "overweight" and "obesity" refer to a person's overall body weight and where the extra weight comes from. Overweight is having extra body weight from muscle, bone, fat, and/or water. Obesity is having a high amount of extra body fat. The most useful measure of overweight and obesity is the body mass index (BMI). BMI is based on height and weight and is used for adults, children, and teens.
Millions of Americans and people worldwide are overweight or obese. Being overweight or obese puts you at risk for many diseases and conditions. The more body fat that you carry around and the more you weigh, the more likely you are to develop coronary artery disease, high blood pressure, type 2 diabetes, gallstones, breathing problems, and certain cancers.
A person's weight is a result of many factors. These factors include environment, family history and genetics, metabolism (the way your body changes food and oxygen into energy), behavior or habits, and other factors.
Certain things, like family history, can't be changed. However, other things – like a person's lifestyle habits – can be changed. You can help prevent or treat overweight and obesity if you:
OutlookReaching and staying at a healthy weight is a long-term challenge for people who are overweight or obese. But it also can be a chance to lower your risk of other serious health problems. With the right treatment and motivation, it's possible to lose weight and lower your long-term disease risk.
What causes overweight and obesity?
Energy balanceFor most people, overweight and obesity are caused by not having energy balance. Weight is balanced by the amount of energy or calories you get from food and drinks (this is called energy IN) equaling the energy your body uses for things like breathing, digesting, and being physically active (this is called energy OUT).
Energy balance means that your energy IN equals your energy OUT. To maintain a healthy weight, your energy IN and OUT don't have to balance exactly every day. It's the balance over time that helps you maintain a healthy weight.
The same amount of energy IN and energy OUT over time = weight stays the same More IN than OUT over time = weight gain More OUT than IN over time = weight loss Overweight and obesity happen over time when you take in more calories than you use.
Many people today aren't very physically active. There are many reasons for this. One reason is that many people spend hours in front of TVs and computers doing work, schoolwork, and leisure activities. In fact, more than 2 hours a day of regular TV viewing time has been linked to overweight and obesity.
Other reasons for not being active include: relying on cars instead of walking to places, fewer physical demands at work or at home because modern technology and conveniences reduce the need to burn calories, and lack of physical education classes in schools for children.
People who are inactive are more likely to gain weight because they don't burn up the calories that they take in from food and drinks. An inactive lifestyle also raises your risk for heart disease, high blood pressure, diabetes, colon cancer, and other health problems.
Our environment doesn't always help with healthy lifestyle habits; in fact, it encourages obesity. Some reasons include:
Genes and family history
Studies of identical twins who have been raised apart show that genes have a strong influence on one's weight. Overweight and obesity tend to run in families. Your chances of being overweight are greater if one or both of your parents are overweight or obese. Your genes also may affect the amount of fat you store in your body and where on your body you carry the extra fat.
Because families also share food and physical activity habits, there is a link between genes and the environment. Children adopt the habits of their parents. So, a child with overweight parents who eat high-calorie foods and are inactive will likely become overweight like the parents. On the other hand, if a family adopts healthful food and physical activity habits, the child's chance of being overweight or obese is reduced.
Sometimes hormone problems cause overweight and obesity. These problems include:
Certain medicines such as corticosteroids (for example, prednisone), antidepressants (for example, Elavil®), and medicines for seizures (for example, Neurontin®) may cause you to gain weight. These medicines can slow the rate at which your body burns calories, increase your appetite, or cause your body to hold on to extra water – all of which can lead to weight gain.
Some people eat more than usual when they are bored, angry, or stressed. Over time, overeating will lead to weight gain and may cause overweight or obesity.
Some people gain weight when they stop smoking. One reason is that food often tastes and smells better. Another reason is because nicotine raises the rate at which your body burns calories, so you burn fewer calories when you stop smoking. However, smoking is a serious health risk, and quitting is more important than possible weight gain.
As you get older, you tend to lose muscle, especially if you're less active. Muscle loss can slow down the rate at which your body burns calories. If you don't reduce your calorie intake as you get older, you may gain weight. Midlife weight gain in women is mainly due to aging and lifestyle, but menopause also plays a role. Many women gain around 5 pounds during menopause and have more fat around the waist than they did before.
During pregnancy, women gain weight so that the baby gets proper nourishment and develops normally. After giving birth, some women find it hard to lose the weight. This may lead to overweight or obesity, especially after a few pregnancies.
Lack of sleep
Studies find that the less people sleep, the more likely they are to be overweight or obese. People who report sleeping 5 hours a night, for example, are much more likely to become obese compared to people who sleep 7–8 hours a night.
People who sleep fewer hours also seem to prefer eating foods that are higher in calories and carbohydrates, which can lead to overeating, weight gain, and obesity over time. Hormones that are released during sleep control appetite and the body's use of energy. For example, insulin controls the rise and fall of blood sugar levels during sleep. People who don't get enough sleep have insulin and blood sugar levels that are similar to those in people who are likely to have diabetes.
Also, people who don't get enough sleep on a regular basis seem to have high levels of a hormone called ghrelin (which causes hunger) and low levels of a hormone called leptin (which normally helps to curb hunger).
What are the health risks of overweight and obesity?Being overweight or obese isn't a cosmetic problem. It greatly raises the risk in adults for many diseases and conditions.
Overweight and obesity-related health problems in adults
This condition occurs when a fatty material called plaque builds up on the inside walls of the coronary arteries (the arteries that supply blood and oxygen to your heart). Plaque narrows the coronary arteries, which reduces blood flow to your heart. Your chances for having heart disease and a heart attack get higher as your body mass index (BMI) increases. Obesity also can lead to congestive heart failure, a serious condition in which the heart can't pump enough blood to meet your body's needs.
High blood pressure (hypertension)
This condition occurs when the force of the blood pushing against the walls of the arteries is too high. Your chances for having high blood pressure are greater if you're overweight or obese.
Being overweight or obese can lead to a buildup of fatty deposits in your arteries that form a blood clot. If the clot is close to your brain, it can block the flow of blood and oxygen and cause a stroke. The risk of having a stroke rises as BMI increases.
Type 2 diabetes
This is a disease in which blood sugar (glucose) levels are too high. Normally, the body makes insulin to move the blood sugar into cells where it's used. In type 2 diabetes, the cells don't respond enough to the insulin that's made. Diabetes is a leading cause of early death, heart disease, stroke, kidney disease, and blindness. More than 80 percent of people with type 2 diabetes are overweight.
Abnormal blood fats
If you're overweight or obese, you have a greater chance of having abnormal levels of blood fats. These include high amounts of triglycerides and low-density lipoprotein (LDL) cholesterol (a fat-like substance often called "bad" cholesterol), and low high-density lipoprotein (HDL) cholesterol (often called "good" cholesterol). Abnormal levels of these blood fats are a risk for heart disease.
This is the name for a group of risk factors linked to overweight and obesity that raise your chance for heart disease and other health problems such as diabetes and stroke. A person can develop any one of these risk factors by itself, but they tend to occur together. Metabolic syndrome occurs when a person has at least three of these heart disease risk factors:
Being overweight or obese raises the risk for colon cancer, breast cancer, endometrial cancer, and gallbladder cancer.
Osteoarthritis is a common joint problem of the knees, hips, and lower back. It occurs when the tissue that protects the joints wears away. Extra weight can put more pressure and wear on joints, causing pain.
Sleep apnea causes a person to stop breathing for short periods during sleep. A person with sleep apnea may have more fat stored around the neck. This can make the breathing airway smaller so that it's hard to breathe.
Obesity can cause menstrual irregularity and infertility in women.
These are hard pieces of stone-like material that form in the gallbladder. They're mostly made of cholesterol and can cause abdominal or back pain. People who are overweight or obese have a greater chance of having gallstones. Also, being overweight may result in an enlarged gallbladder that may not work properly.
Overweight and obesity-related health problems in children and teensOverweight and obesity also increase the health risks for children and teens. Type 2 diabetes was once rare in American children. Now it accounts for 8 to 45 percent of newly diagnosed diabetes cases. Also, overweight children are more likely to become overweight or obese as adults, with the same risks for disease.
Who is at risk for overweight and obesity?
Populations affectedOverweight and obesity affect Americans of all ages, sexes, racial/ethnic groups, and educational levels. This serious health problem has been growing over the years. In fact, overweight and obesity in adults have doubled since 1980, and overweight in children and teens has tripled.
AdultsAccording to the National Health and Nutrition Examination Survey (NHANES) 2003–2004, about one-third of adults in the United States are overweight and slightly more than one-third are obese. The survey also shows differences in overweight and obesity according to racial/ethnic groups.
Children and teensAccording to NHANES 2003–2004, overweight and the risk for overweight is rising in children and teens. The survey shows that:
IncomeOverweight and obesity are also common in groups with low incomes. Women with low incomes are about 50 percent more likely to be obese than women with higher incomes. Among children and teens, overweight in non-Hispanic White teens is related to a lower family income.
Low-income families also buy more high-calorie, high-fat foods, which may add to the problem. This is because they tend to cost less than more healthful foods such as fruits and vegetables.
What are the signs and symptoms of overweight and obesity?Weight gain usually happens over time. Most people know when they've gained weight. Some of the signs of overweight or obesity include:
How are overweight and obesity diagnosed?The most common way to find out whether you're overweight or obese is to figure out your body mass index (BMI). BMI is an estimate of body fat and a good gauge of your risk for diseases that occur with more body fat. The higher your BMI, the higher your risk of disease. BMI is calculated from your height and weight.
Body mass index for adults
Use this table to learn your BMI. First, find your height on the far left column. Next, move across the row to find your weight. Once you've found your weight, move to the very top of that column. This number is your BMI.
What does body mass index mean?
Although BMI can be used for most men and women, it does have some limits:
Body mass index for children and teens
Overweight is defined differently for children and teens than it is for adults. Because children are still growing and boys and girls mature at different rates, BMIs for children and teens compare their heights and weights against growth charts that take age and sex into account. This is called BMI-for-age percentile. A child or teen's BMI-for-age percentile shows how his or her BMI compares with other boys and girls of the same age.
What does the BMI-for-age percentile mean?
Waist circumferenceHealth care professionals also may take your waist measurement. This helps to screen for the possible health risks that come with overweight and obesity in adults. If you have abdominal obesity and most of your fat is around your waist rather than at your hips, you're at higher risk for heart disease and type 2 diabetes. This risk goes up with a waist size that is greater than 35 inches for women or greater than 40 inches for men.
You too may want to measure your waist size. To do so correctly, stand and place a tape measure around your middle, just above your hipbones. Measure your waist just after you breathe out.
Specialists involvedA primary care doctor (or pediatrician for children and teens) will assess your BMI, waist measurement, and overall health risk. If you're overweight or obese, or have a large waist size, your doctor should explain the health risks and find out whether you're interested and willing to lose weight. If you are, you and your doctor should work together to create a treatment plan. The plan should include weight loss goals and treatment options that are realistic for you.
Your doctor may send you to other health care specialists if you need expert care. These specialists may include:
How are overweight and obesity treated?Successful treatments for weight loss include setting goals and making lifestyle changes such as eating fewer calories and being more physically active. Drug therapy and weight loss surgery are also options for some people if lifestyle changes don't work.
Set realistic ("do-able") goalsSetting the right weight loss goals is an important first step to losing and maintaining weight.
For children and teens
Lifestyle changesFor long-term weight loss success, it's important for you and your family to make lifestyle changes:
Cutting back on calories (energy IN) will help you lose weight. To lose 1 to 2 pounds a week, adults should cut back their calorie intake by 500 to 1,000 calories a day.
For overweight children or teens, it's important to slow the rate of weight gain; however, reduced-calorie diets aren't advised before you talk to a health care provider.
Healthy eating plan
A healthy eating plan gives your body the nutrients it needs every day. It has enough calories for good health, but not so many that you gain weight.
A healthy eating plan also will lower your risk for heart disease and other conditions. A plan low in total, saturated, and trans fat; cholesterol; and sodium (salt) will help to lower your risk for heart disease. Cutting down on fats and added sugars also can help you eat fewer calories and lose weight. Healthful foods include:
Foods to limit. Foods that are high in saturated and trans fats and cholesterol raise blood cholesterol levels and also may be high in calories. These fats raise the risk of heart disease, so they should be limited.
Saturated fat is found mainly in:
Portion size. A portion is the amount of food that you choose to eat for a meal or snack. It's different from a serving, which is a measured amount of food and is noted on the nutrition label on food packages.
Anyone who has eaten out lately is likely to notice how big the portions are. In fact, they're oversized. These ever-larger portions have changed what we think of as normal.
Cutting back on portion size is a good way to help you eat fewer calories and balance your energy IN.
Food weight. Studies have shown that we all tend to eat a constant "weight" of food. Ounce for ounce, our food intake is fairly constant. Knowing this, you can lose weight if you eat foods that are lower in calories and fat for a given measure of food. For example, replacing a full-fat food product that weighs 2 ounces with one that's the same weight but lower in fat helps you cut back on calories. Another helpful practice is to eat foods that contain a lot of water like vegetables, fruits, and soups.
Physical activityStaying active and eating fewer calories will help you lose weight and keep the weight off over time. Physical activity also will benefit you in other ways. It will:
Many people lead inactive lives and may not be motivated to do more physical activity. Some people may need help and supervision when they start a physical activity program to avoid injury.
If you're obese, or if you haven't been active in the past, start physical activity slowly and build up the intensity a little at a time. When starting out, one way to be active is to do more "everyday" activities such as taking the stairs instead of the elevator and doing household chores and yard work. The next step is to start walking, biking, or swimming at a slow pace, and then build up the amount of time you exercise or the intensity level of the activity.
To lose weight and gain better health, it's important to get moderate-intensity physical activity. Choose activities that you enjoy and that fit into your daily life. A daily, brisk walk is an easy way to be more active and improve your health. Use a pedometer to count your daily steps and keep track of how much you're walking. Try to increase the number of steps you take each day.
Other examples of moderate-intensity physical activity include dancing, bicycling, gardening, and swimming. For greater health benefits, try to step up your level of activity or the length of time you're active. For example, start walking for 10 to 15 minutes three times a week, and then build up to brisk walking for 60 minutes, 5 days a week. You also can break up the amount of time that you're physically active into shorter amounts such as 15 minutes at a time.
Behavioral changesChanging your behaviors or habits around food and physical activity is important for losing weight. The first step is to understand the things that lead you to overeat or have an inactive lifestyle. The next step is to change these habits.
The list below gives you some simple tips to help build healthier habits. Change your surroundings. You may be more likely to overeat when watching TV, when treats are available in the office break room, or when you're with a certain friend. You also may not be motivated to take the exercise class you signed up for. But you can change these habits.
Reward success. Reward your success for meeting your weight loss goals or other achievements with something you would like to do, not with food. Choose rewards that you'll enjoy, such as a movie, music CD, an afternoon off from work, a massage, or personal time.
Weight loss medicinesWeight loss medicines approved by the Food and Drug Administration (FDA) may be an option for some people. These medicines should be used after making lifestyle changes, and only as part of a program that includes diet, physical activity, and behavioral changes.
Weight loss medicines may be suitable for people who haven't been able to lose 1 pound a week on a low-calorie diet, have been physically active for 6 months, and have a BMI of 27 or greater with a risk for heart disease and other health conditions. These medicines also may be suitable for people who have a BMI of 30 or greater.
The FDA has approved two weight loss medicines for long-term use: sibutramine (Meridia®) and orlistat (Xenical®). These medicines cause a weight loss between 4 and 22 pounds, although some people lose more weight. Most of the weight loss occurs within the first 6 months of taking the medicine.
Some prescription medicines are used to treat weight loss, but aren't FDA-approved for treating obesity. They include:
Over-the-counter (OTC) products often claim that a person taking them will lose weight. The FDA doesn't regulate these products because they're considered dietary supplements, not medicines. However, many of these products have serious side effects and aren't generally recommended. A few OTC products include:
Weight loss surgery
Weight loss surgery may be an option for people with extreme obesity (BMI of 40 or greater) when other treatments have failed. It's also an option for people with a BMI of 35 or greater who have life-threatening conditions such as:
Lifelong medical followup is needed after both surgeries. A monitoring program both before and after surgery also is advised to help you with diet, physical activity, and coping skills.
If you think you would benefit from weight loss surgery, talk to your doctor. Ask whether you're a candidate for the surgery and discuss the risks, benefits, and what to expect.
Weight loss maintenance
Maintaining your weight loss over time can be a challenge. For adults, weight loss is a success if you lose at least 10 percent of your initial weight and you don't regain more than 6 or 7 pounds in 2 years. You also must keep a lower waist circumference – at least 2 inches lower than your waist circumference before you lost weight.
After 6 months of keeping off the weight, you can think about losing more if:
Adults should aim for 60 to 90 minutes of daily moderate-intensity physical activity. Children and teens should aim for 60 minutes of physical activity a day.
How can overweight and obesity be prevented?Staying at a healthy weight and preventing overweight and obesity can be achieved through living a healthy lifestyle. Because lifetime habits begin in childhood, it's important for parents and families to create habits that encourage healthy food choices and physical activity early in life.
The evidence-based program offers parents and families tips and fun activities to encourage healthy eating, increase physical activity, and reduce time spent being inactive. Currently, more than 140 communities around the country are participating in We Can! programs for parents and youth. These community groups include hospitals, health departments, clinics, faith-based organizations, YMCAs, schools, and more.
Related category• HEALTH AND DISEASE
Source: U.S. National Heart, Lung and Blood Institute
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