Sarcopenia is the name (fairly recently) given to age-related muscle loss, a situation that most people find themselves in with advancing age. In past years, researchers have investigated whether this might related to tendencies for diet to change with age, such as reduced protein intake for example. Interestingly, however, there is also solid evidence for the practice of calorie restriction to slow the process of sarcopenia.

Back in 2005, one group of scientists painted a fairly convincing argument for dysfunctional processing of the essential amino acid leucine as the cause of sarcopenia, a dysfunction that can be overcome by simply consuming more leucine. Those researchers went on to point the finger at increasing chronic inflammation that occurs with aging as a root cause of this amino acid processing problem:

In old rats, the ability of leucine to stimulate muscle protein synthesis was significantly decreased compared with adults. This defect was reversed when old rats were supplemented with antioxidants [but it] was not related to increased oxidative damage ... These effects could be mediated through a reduction in the inflammatory state, which decreased with antioxidant supplementation.

You can look back in the Fight Aging! archives for more of a background on inflammation and aging:

Inflammation participates importantly in host defenses against infectious agents and injury, but it also contributes to the pathophysiology of many chronic diseases. Interactions of cells in the innate immune system, adaptive immune system, and inflammatory mediators orchestrate aspects of the acute and chronic inflammation that underlie diseases of many organs.

Let me direct your attention to another more recent demonstration of the link between age-related chronic inflammation and sarcopenia in rats:

Recently, low grade inflammation has been suspected to be one of the factors responsible for the decreased sensitivity of muscle protein metabolism to food intake. This study was undertaken to examine the effect of long term prevention of low grade inflammation on muscle protein metabolism during aging. Older rats (20 month of age) were separated into two groups: a control group and a group (IBU) in which low grade inflammation had been reduced with a non steroidal anti inflammatory drug (ibuprofen). After 5 months of treatment, inflammatory markers and cytokines levels were significantly improved in treated old rats when compared to the controls ... controlling the development of low grade inflammation in old rats significantly decreased muscle mass loss between 20 and 25 months of age. In conclusion, the observations made in this study have identified low grade inflammation as an important target for pharmacological, nutrition and lifestyle interventions that aim to limit sarcopenia and muscle weakness in the rapidly growing elderly population in Europe and North America.

Turning back to calorie restriction once again, you might recall that reduced calorie intake does in fact reduce the level of inflammation suffered with advancing age, an effect possibly achieved though loss of visceral fat tissue. Taken together, all of this is one more reason to take better care of your health, and keep up with those practices known to reduce inflammation - such as not letting yourself get fat.

Rieu I, Magne H, Savary-Auzeloux I, Averous J, Bos C, Peyron MA, Combaret L, & Dardevet D (2009). Reduction of low grade inflammation restores blunting of postprandial muscle anabolism and limits sarcopenia in old rats. The Journal of physiology PMID: 19752122