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.

Overview

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 heart 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:

• Follow a healthy diet, while keeping your calorie needs in mind
• Are physically active
• Limit the time you spend being physically inactive

Weight loss medicines and surgery also are options for some people who need to lose weight if lifestyle changes don't work.

Outlook

Reaching 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 Balance

For 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.

Achieving and maintaining a healthy weight is about FINDING A BALANCE through healthy eating and physical activity.

Other Causes

Physical Inactivity

Many Americans 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.

Environment

Our environment doesn't always help with healthy lifestyle habits; in fact, it encourages obesity. Some reasons include:

• Lack of neighborhood sidewalks and safe places for recreation. Not having area parks, trails, sidewalks, and affordable gyms makes it hard for people to be physically active.
• Work schedules. People often say that they don't have time to be physically active given the long hours at work and the time spent commuting back and forth to work.
• Oversized food portions. Americans are surrounded by huge food portions in restaurants, fast food places, gas stations, movie theaters, supermarkets, and even home. Some of these meals and snacks can feed two or more people. Eating large portions means too much energy IN. Over time, this will cause weight gain if it isn't balanced with physical activity.
• Lack of access to healthy foods. Some people don't live in neighborhoods that have supermarkets that sell healthy foods such as fresh fruits and vegetables. Or if they do, these items are often too costly.
• Food advertising. Americans are surrounded by ads from food companies. Often children are the targets of advertising for high-calorie, high-fat snacks and sugary drinks. The goal of these ads is to sway people to buy these high-calorie foods, and often they do.

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.

Health Conditions

Sometimes hormone problems cause overweight and obesity. These problems include:

• Underactive thyroid (also called hypothyroidism). This is a condition in which the thyroid gland doesn't make enough thyroid hormone. Lack of thyroid hormone will slow down your metabolism and cause weight gain. You'll also feel tired and weak.
• Cushing's syndrome. This is a condition in which the body's adrenal glands make too much of the hormone cortisol. Cushing's syndrome also can happen when people take high levels of medicines such as prednisone for long periods of time. People with Cushing's syndrome gain weight, have upper-body obesity, a rounded face, fat around the neck, and thin arms and legs.
• Polycystic ovarian syndrome (PCOS). This is a condition that affects about 5 to 10 percent of women of childbearing age. Women with PCOS often are obese, have excess hair growth, and have reproductive and other health problems due to high levels of hormones called androgens.

Medicines

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.

Emotional Factors

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.

Smoking

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.

Age

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.

Pregnancy

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).

Related Video

From nightly sleep to genes, Dr. Marc Bessler explains the factors that lead to obesity in the following video from BigThink:

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

Heart Disease

This condition occurs when a fatty material called plaque (plak) 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)

Hypertension 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.

Stroke

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.

Metabolic Syndrome

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:

• A large waistline. This is also called abdominal obesity or "having an apple shape." Having extra fat in the waist area is a greater risk factor for heart disease than having extra fat in other parts of the body, such as on the hips.
• Abnormal blood fat levels, including high triglycerides and low HDL cholesterol.
• Higher than normal blood pressure.
• Higher than normal fasting blood sugar levels.

Cancer

Being overweight or obese raises the risk for colon, breast, endometrial, and gallbladder cancers.

Osteoarthritis

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

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.

Reproductive Problems

Obesity can cause menstrual irregularity and infertility in women.

Gallstones

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 Teens

Overweight 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 Affected

Overweight 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.

Adults

According 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.

• In women, overweight and obesity are highest for non-Hispanic Black women (about 82 percent), compared to about 75 percent for Mexican American women and 58 percent for non-Hispanic White women.
• In men, overweight and obesity also are higher for minority groups. They're highest for Mexican American men (about 76 percent), compared to about 71 percent for non-Hispanic White men and about 69 percent for non-Hispanic Black men.

Children and Teens

According to NHANES 2003-2004, overweight and the risk for overweight is rising in children and teens. The survey shows that:

• About 19 percent of school-aged children and about 17 percent of teens are overweight.
• About 18 percent of school-aged children and about 17 percent of teens are at risk for overweight.

There are also some differences in overweight according to racial/ethnic groups.

• In male children and teens, overweight is highest for Mexican Americans (about 22 percent), compared to 17 percent for non-Hispanic Whites and about 16 percent for non-Hispanic Blacks.
• In female children and teens, overweight is highest for non-Hispanic Blacks (23 percent), compared to 16 percent for Mexican Americans and about 14 percent for non-Hispanic Whites.

Income

Overweight 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:

• Clothes feeling tight and needing a larger size.
• The scale showing that you've gained weight.
• Having extra fat around the waist.
• A higher than normal body mass index and waist circumference.

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. You or your health care provider can use the chart below or the National Heart, Lung, and Blood Institute's online BMI calculator to figure out your BMI.