Muscle wasting coupled with abdominal obesity was present in around one in ten men under 50, with low bone mineral density also being common, a study of Italian men living with HIV has found.
The study, published in the Journal of Endocrinological Investigation, also found that low muscle mass and low bone mineral density were associated with low levels of the sex hormones testosterone and estradiol.
The research was carried out to investigate the relationship between sex hormones and body composition in younger men with HIV. Low muscle mass, or sarcopenia, remains common in men with HIV despite earlier diagnosis and treatment. In younger men with HIV, muscle loss may appear earlier than in people without HIV. In the general population, sarcopenia is more common in people over 60 years old.
Loss of muscle tissue leads to loss of strength for carrying out everyday tasks, loss of stamina, poor balance and slowed walking.
The most common causes of muscle loss are physical inactivity, obesity, chronic health conditions such as kidney disease and diabetes, and low sex hormone levels.
The extent to which muscle loss is influenced by low levels of testosterone in men with HIV is unclear, and the relationship between sex hormone levels and bone mineral density is uncertain too.
Researchers at universities in Modena and Bologna wanted to understand whether sex hormone levels are associated with low muscle mass in younger men with HIV, and the proportions of men with HIV with both low muscle mass and high body fat content. This group may be especially vulnerable to falls, frailty and metabolic problems including diabetes and cardiovascular disease as they grow older.
They carried out a cross-sectional study of 307 men with HIV under the age of 50 who were under follow-up at the Modena HIV Metabolic Clinic. Participants had a median age of 47 years and had been living with HIV for a median of 16 years.
The study assessed body composition, bone mineral density, hormones and metabolic measurements.
The analysis of body composition used two scales of measurement to assess sarcopenia (reduced muscle mass):
- Appendicular lean mass index (ALMI), which calculates lean body mass divided by height squared
- Appendicular lean mass/body weight (ALM/W), which divides lean body mass by total body weight. This has been recommended by a European expert panel as the preferred means of diagnosing sarcopenic obesity.
Using ALMI, 34% were found to have sarcopenia, while using ALM/W showed that 14% had sarcopenia. Men with sarcopenia diagnosed by ALMI had lower body mass index and significantly lower bone mineral density at all sites apart from the lumbar measurement point. However, men with sarcopenia diagnosed by ALM/W had higher body mass index than those without sarcopenia and showed no difference with the rest of the cohort in bone mineral density.
Sarcopenia diagnosed by both measurements was associated with lower free testosterone and total testosterone. In those diagnosed with sarcopenia by ALMI, the ratio of estradiol to testosterone was significantly lower.
Despite the differences in the prevalence of sarcopenia identified by the two methods of measurement, the prevalence of sarcopenic obesity – obesity with low muscle mass – was almost the same (11% for ALMI and 12% ALM/W respectively). Obesity in this study was defined as either a body fat percentage above 26% in a person with a body mass index below 30 (classified as ‘hidden’ obesity), or a body fat percentage above 26% in a person with a body mass index of 30 or above ('overt' obesity) . In this cohort, 23% of participants had hidden obesity, while 3% had overt obesity.
A multivariate analysis found that sarcopenic obesity was associated with low estradiol (<18pg/ml), time since HIV diagnosis and low free testosterone, when sarcopenia was measured by ALMI.
The study investigators say that the pattern of low muscle mass and low bone mineral density observed in this study is associated with falls, fractures and frailty. They add that sarcopenic obesity is associated with an increased risk of death or serious illness in the general population.
“Bone and muscle closely interact with each other not only anatomically, but also chemically and metabolically,” they note.
However, the study findings show that testosterone supplements may not resolve osteosarcopenia. The low ratio of estradiol to testosterone in men with sarcopenia in this cohort indicates low oestrogen levels and the study investigators say that more research is needed to investigate the extent to which oestrogen protects against sarcopenia in men with HIV.
“This study first highlights and then confirms the central role of sex steroids, estrogens rather than androgens, in the strict interconnection between bone, muscle and adipose tissue […] These findings reiterate […] the deep involvement of sex hormones in the vicious circle connecting bone, fat, and skeletal muscle,” say the study investigators.
The advice for anyone experiencing muscle loss is to ensure they have a healthy diet containing adequate amounts of protein (25-30 grams per meal). Regular resistance exercise can reverse muscle loss and maintain muscle in later life.
De Vicentis S et al. Sarcopenic obesity and reduced BMD in young men living with HIV; body composition and sex steroids interplay. Journal of Endocrinological Investigation, published online 20 April 2024.