Obesity

Obesity refers specifically to having too much body fat. It usually also means being very overweight. People may be overweight without being obese.

Some people think that being overweight or obese is the opposite of undernutrition, that overweight or obese people are overnourished. However, overweight or obese people may not consume enough of the nutrients needed for good health and may therefore be undernourished. For example, they may not consume enough fiber, vitamins, or minerals.

In the United States, the percentage of older people who are obese has been increasing during the last few years. People may be obese throughout most of their life, or they may become obese late in life.

Some extra body fat is not necessarily bad for older people. Fat is the way the body stores energy. Some disorders, such as cancer or infections, can increase the body's need for energy. Some extra body fat may come in handy if one of these disorders develops. Fat around the hips and buttocks helps protect bones from being broken during a fall. And people who weigh more are less likely to develop osteoporosis.

But too much body fat is unhealthy for older people as well as for younger people. The risk of health problems increases as body fat (and weight) increases. For example, heart disorders, high blood pressure, stroke, diabetes, some cancers, osteoarthritis, gallbladder disorders, and obstructive sleep apnea are more common among obese people.

Causes

In one sense, the cause of being overweight or obese is simple. The cause is consuming more calories than the body needs over a period of time. But why people consume more than the body needs and what determines how many calories the body needs are more complex questions.

Most people gain body fat and weight as they age. These changes may occur if older people become less physically active but do not eat any less. Physical inactivity is considered one of the main causes of obesity.

Also as people age, levels of hormones, such as growth hormone and testosterone, decrease. When growth hormone and testosterone levels decrease, the amount of muscle decreases and the amount of body fat increases. Muscle burns more calories than fat, so this change may contribute to weight gain as well as to increased body fat.

People may eat too much for many reasons. Some people eat more when they are bored, lonely, or under stress.

Eating foods that are high in calories, even when the amounts are relatively small, can result in weight gain. Many convenience foods and foods eaten in a restaurant are high in fat and in calories.

Many drugs used to treat common disorders promote weight gain. Examples are some antidepressants, insulin, and corticosteroids. Taking corticosteroids causes an unusual type of obesity. Fat accumulates only in the trunk. The arms and legs may become thinner because muscle is lost.

Rarely, hormonal disorders cause obesity. A disorder of overactive adrenal glands (Cushing's disease) causes the same type of obesity as corticosteroids. A low level of thyroid hormone (hypothyroidism) slows the rate at which calories are used (metabolic rate). Thus, this disorder may result in weight gain.

The nicotine in tobacco decreases appetite and increases the metabolic rate. Stopping smoking usually results in weight gain because the metabolic rate slows and the body thus burns fewer calories. People who smoke may remain thin, but fat tends to accumulate around their waist and abdomen. This accumulation increases their risk of health problems, even if they remain within a normal weight range.

Symptoms

Obesity may cause no specific symptoms other than a change in appearance and in the way clothes fit.

Osteoarthritis of the hips and knees is more common among obese people because excess weight puts more stress on the joints. Low back pain is also common. Obese people may tire easily and become short of breath after slight exertion.

Some obese people have difficulty sleeping because of obstructive sleep apnea. This disorder interferes with breathing during sleep. When the muscles of the throat relax during sleep, tissue in the wall of the throat may partially block the airway. As a result, people snore loudly, sleep restlessly, and may suddenly wake up gasping and choking. They may feel sleepy during the day.

Obese women may feel pain in their pelvis or pressure on the bladder, rectum, or uterus. The pressure of excess weight can weaken the muscles and other tissues that support pelvic organs (bladder, rectum, and uterus). This pressure may cause or worsen a pelvic support disorder.

Diagnosis

Usually, obesity can be identified based on appearance. However, health care practitioners usually measure weight and height and use these measurements to calculate body mass index (BMI). The BMI indicates whether people are overweight or obese and how severe the obesity is.

Treatment

Treatment of weight gain and obesity involves exercising and decreasing the number of calories consumed. Any exercise, such as regularly walking in a mall or around the neighborhood or lifting light weights, can lead to gradual weight loss as long as the number of calories consumed is not increased. To lose weight, a person must consume fewer calories than the body burns. So decreasing the number of calories consumed is usually also recommended. Avoiding between-meal snacks may be all that is needed.

Learning to identify activities and feelings that trigger overeating may help people stop overeating. For example, snacking while watching television can be replaced with other activities, such as exercise or crafts. An absorbing, purposeful activity or hobby, such as painting or gardening, may take the mind off anxieties, which can trigger overeating.

Older people who are trying to eat less should drink plenty of fluids. They may need to take a multivitamin with minerals. Obese older people who are losing weight should be evaluated periodically to check for serious disorders that may be causing the weight loss.

Most drugs that help reduce body weight are not recommended for older people because of their side effects. But orlistat may be useful for obese older people who cannot exercise or change their diet. Orlistat blocks fat absorption from the digestive tract. However, deficiencies of some vitamins and minerals can develop. People taking orlistat are monitored closely by their doctor.