• What Is Lipodystrophy?
  
• Is Lipo Dangerous?
  
• What Causes Lipo?
  
• Can Lipo Be Treated?
  
• The Bottom Line
  

What Is Lipodystrophy?

Lipodystrophy, or "lipo" for short, is a collection of body shape changes in people taking antiretroviral medications (ARVs). "Lipo" refers to fat, and "dystrophy" means bad growth. These changes include fat loss, fat deposits, and metabolic changes.

Fat loss occurs in the arms, legs or face (sunken cheeks). This may be the most common feature of lipo.

Fat deposits can show up in the stomach, the back of the neck (a "buffalo hump"), the breasts (in both men and women) or other areas.

Metabolic changes can include increases in blood fats or lactic acid. Some people get "insulin resistance."

• Blood fats include cholesterol and triglycerides.
• Lactic acid is produced when glucose (sugar) is used by the cells. Damage to the mitochondria (see Fact Sheet 556) or the liver can increase the amount of lactic acid. Too much lactic acid can cause health problems.
• Normally, insulin moves sugar (glucose) into the cells to produce energy. With insulin resistance, less glucose gets into the cells. More stays in the blood.

Fact Sheet 123 has information on lab tests for glucose, cholesterol and triglycerides.

There is no clear definition of lipo. As a result, health care providers report that between 5% and 75% of patients taking antiretroviral medications (ARVs) have some signs of lipo. Most researchers think the rate is about 50%.

These changes were first called "Crix belly," because they were noticed in people taking the protease inhibitor Crixivan (indinavir). However, lipo can develop in people taking almost any type of antiretroviral therapy (ART).

Is Lipo Dangerous?

Although it is not life threatening, lipo is a serious problem.

• High blood fats can increase the risk of heart disease.
• Enlarged breasts in women can be painful.
• Lactic acidosis, although rare, can be fatal. See Fact Sheet 556 for more information.
• Body shape changes can be very upsetting. Some patients even stop taking their medications.
• Fear of body shape changes keeps some people from starting ART.
• Insulin resistance can lead to diabetes and weight gain, and can increase the risk of heart disease.
• Fat deposits behind the neck (buffalo humps) can get big enough to cause headaches and problems with breathing and sleeping.

No researcher has suggested that people with lipo should stop taking ART.

What Causes Lipo?

We do not know what causes lipo. There may be different causes for the various symptoms.

One theory is that protease inhibitors interfere with the body's processing of fat. However, some patients who have never taken protease inhibitors have lipo. Recent research suggests that zidovudine (Retrovir, AZT) and stavudine (Zerut, D4T) have the greatest effect on fat loss. Efavirenz (Sustiva) may also contribute.

Another theory is that insulin resistance plays a role in lipo. People with insulin resistance tend to gain weight in the abdomen.

Lipo may also be similar to "Syndrome X" which can occur in people who have recovered from serious illnesses like childhood leukemia or breast cancer. For people with HIV, this may be caused by the recovery of the immune system after effective ART.

A large study found that the following factors appear to increase the risk of developing lipodystrophy:

• Age over 40 years
• Having AIDS for over 3 years
• Lowest CD4 count was below 100
• White race

Can Lipo Be Treated?

Because we don't know what causes lipo, we don't know how to treat it. Body changes sometimes get worse, stop or get better by themselves.

Some changes in ART lead to improvements in certain signs of lipo. However, it takes a long time to reverse changes in body shape.

Some fat deposits can be cut out surgically, or removed by liposuction. Cosmetic surgery (implants or injections) is the only proven way to deal with sunken cheeks. These procedures have some risks, and the results may only be temporary.

A recent study found that increased exercise helped. Some health care providers recommend changes in diet. For example, more fiber in the diet may control insulin resistance and help decrease abdominal fat. Testosterone is also being studied to help with lipo symptoms. A recent study showed good results in reducing fat accumulations with human growth hormone.

High cholesterol or glucose should be treated the same way as for people without HIV. Some health care providers use medications to lower cholesterol and triglycerides, or to improve insulin sensitivity. More attention is being paid to assessing and reducing the risk of heart disease in patients with HIV.

The Bottom Line

Lipo is a collection of changes in metabolism and body shape in people taking ARVs. There is no clear definition of lipo. It is difficult to know exactly how many people have it. Also, without knowing what causes lipo, we don't yet know how to treat it.

Changing or stopping ART is not recommended.

Until we know more about specific causes and treatments for lipo, its symptoms are treated the same way as for the general population.