Weight loss and wasting syndrome are two AIDS-related complications that, if not adequately treated, can be life threatening. Even though anti-HIV therapies have helped reduce the risk of weight loss and wasting syndrome, both problems still occur. According to a study reported in late 1997, as many as 25% of HIV-positive people receiving triple-drug anti-HIV therapy still experience some degree of weight loss and/or wasting.
Is there a difference between weight loss and wasting?
Yes. As its name implies, weight loss refers to a loss of body weight. Wasting syndrome refers to a loss of body mass or size, most notably muscle mass (sometimes referred to as "lean body mass"). Very often, both occur at the same time. However, this is not always the case. It is possible that someone who is losing weight might not lose muscle mass. It is also possible that someone losing muscle mass might not lose a lot of weight. For example, some HIV-positive people lose a lot of muscle. Yet they may experience an increase in fat. This can cause weight to stay the same, even though muscle wasting is going on.
In people who do not have HIV, weight loss is not usually a serious problem. For example, someone who goes on a diet will eventually lose weight. To make up for the lack of food being eaten, the body will naturally burn fat – either in the blood or stored in cells – to help meet its energy needs. At the same time, the body works to protect protein during periods of dieting or physical activity. Protein is needed to build muscle, cells, and organs in the body. In other words, most people can afford to lose fat. They cannot afford to lose protein.
In people with HIV, especially during periods of illness (e.g., MAC or tuberculosis), the energy demands of the body increase. Turning fat into energy also requires a lot of work in the body. To help save energy, the body may go after protein to fuel its energy needs. This is because protein is much easier to convert into energy than fat. Also, protein is needed to help repair damaged organs and to replace immune system cells lost during periods of illness.
If there isn't enough protein in the blood - which might occur if someone is not eating all the protein they should during times of illness - the body will go after a major source of protein in the body: muscle. Depending on the energy needs of the body, which depends on how severe or how long the illness lasts, either a little or a lot of muscle can be lost. And while the loss of small amounts of muscle is not usually serious, losing large amounts of muscle can be dangerous.
There are, essentially, two different types of wasting. The first type reflects periods of rapid weight loss and muscle wasting. As discussed above, this type is most commonly found in people experiencing particular opportunistic infections (OIs), such as MAC, tuberculosis, or Pneumocystis pneumonia (PCP). Given the benefits of anti-HIV therapy and prophylaxis, people living with HIV now stand a much better chance of either avoiding or recovering faster from an OI. This is certainly good news in terms of preventing one of the most common types of wasting.
The second type reflects more gradual losses in both weight and muscle. Unlike the first type, which most often applies to people with AIDS, gradual wasting can occur at any time. It can also occur for any number of reasons and may be due to HIV infection itself.