Interactions Among Sex, HIV Infection, and Fat Redistribution
Interactions Among Sex, HIV Infection, and Fat Redistribution
The interactions among sex, HIV infection, and body fat redistribution are uncertain. We retrospectively compared total, subcutaneous, and visceral adipose tissue (TAT, SAT, VAT) contents, as determined by whole body MRI, in 85 HIV-infected persons, including 48 HIV-positive persons with self-reported changes in body shape, and matched healthy controls. The effect of sex on regional fat contents differed among HIV-infected persons with and without self-reported changes in body shape. Women without changes had significantly less SAT and TAT than did controls, while men with changes had significantly less SAT and TAT than did controls. Higher contents of VAT were found in both men and women with self-reported changes in body shape.
Fat distribution refers to the relative contents of adipose tissue in anatomically distinct regions of the body. Fat distribution has been classified in a variety of ways (eg, upper body versus lower body, central versus peripheral, visceral versus subcutaneous). The importance of understanding body fat distribution is derived from observations that adipose tissue from the various compartments affects metabolism differently. The ultimate consequences of upper body and visceral fat accumulation are adverse effects on health outcomes, especially those that relate to insulin resistance and cardiovascular disease.
Many factors, including sex, race, age, and total body fat content, affect body fat distribution under normal circumstances. During the past several years, altered body fat distribution also has been observed in HIV-infected individuals. The changes, which have been seen in men, women, and children, include depletion of subcutaneous adipose tissue (SAT), and accumulation of fat in the visceral compartment (VAT) as well as other regions, such as the dorsocervical, mammary, axillary, and other upper body fat depots.
Body composition changes are often accompanied by hyperlipidemia and evidence of insulin resistance or even glucose intolerance, though the specific interrelationships are uncertain. The prevalence of these changes varies widely in different series, in part because of uncertainty surrounding the clinical-case definition. Although the etiology and pathogenesis underlying these changes are uncertain, hypertriglyceridemia developed in healthy volunteers taking a protease inhibitor, which suggests a direct drug effect on lipid metabolism. On the other hand, body fat redistribution may be found in the presence or absence of protease inhibitor therapy. Several factors, including age, length of time on therapy, nadir CD4 lymphocyte count, baseline plasma HIV RNA content, and others, have been shown to influence the presence of fat redistribution.
A sexual dimorphism in HIV-associated malnutrition has been demonstrated, with women losing greater relative amounts of body fat, compared with lean tissue, than are men. Several investigators have suggested that quantitative differences in fat redistribution also occur in HIV-infected men and women. In general, men were more likely than women to complain of fat depletion, especially in the arms, legs, and face, while women were more likely than men to complain of fat accumulation, especially in the abdomen and breasts. However, those studies were based largely on subjective self-report and did not include objective measurements of body fat content or comparison with healthy controls.
While the ability of self-report to accurately assess fat redistribution has been validated for epidemiologic studies in HIV-negative individuals, its clinical utility is less well accepted. In fact, one study documented discrepancies between subjective and objective estimates of change in body fat distribution as a result of switching antiretroviral agents. Such distinctions are important, since metabolic alterations as well as clinical outcomes appear to be related to absolute changes, rather than relative ones, in the sizes of fat compartments.
The purpose of this study was to compare differences between the sizes of body fat compartments in healthy controls and HIV-infected men and women with and without self-reported changes in body shape. The sizes of the VAT and SAT compartments were determined by whole body MRI scanning, and the results were compared with those of controls using a case-control analysis.
The interactions among sex, HIV infection, and body fat redistribution are uncertain. We retrospectively compared total, subcutaneous, and visceral adipose tissue (TAT, SAT, VAT) contents, as determined by whole body MRI, in 85 HIV-infected persons, including 48 HIV-positive persons with self-reported changes in body shape, and matched healthy controls. The effect of sex on regional fat contents differed among HIV-infected persons with and without self-reported changes in body shape. Women without changes had significantly less SAT and TAT than did controls, while men with changes had significantly less SAT and TAT than did controls. Higher contents of VAT were found in both men and women with self-reported changes in body shape.
Fat distribution refers to the relative contents of adipose tissue in anatomically distinct regions of the body. Fat distribution has been classified in a variety of ways (eg, upper body versus lower body, central versus peripheral, visceral versus subcutaneous). The importance of understanding body fat distribution is derived from observations that adipose tissue from the various compartments affects metabolism differently. The ultimate consequences of upper body and visceral fat accumulation are adverse effects on health outcomes, especially those that relate to insulin resistance and cardiovascular disease.
Many factors, including sex, race, age, and total body fat content, affect body fat distribution under normal circumstances. During the past several years, altered body fat distribution also has been observed in HIV-infected individuals. The changes, which have been seen in men, women, and children, include depletion of subcutaneous adipose tissue (SAT), and accumulation of fat in the visceral compartment (VAT) as well as other regions, such as the dorsocervical, mammary, axillary, and other upper body fat depots.
Body composition changes are often accompanied by hyperlipidemia and evidence of insulin resistance or even glucose intolerance, though the specific interrelationships are uncertain. The prevalence of these changes varies widely in different series, in part because of uncertainty surrounding the clinical-case definition. Although the etiology and pathogenesis underlying these changes are uncertain, hypertriglyceridemia developed in healthy volunteers taking a protease inhibitor, which suggests a direct drug effect on lipid metabolism. On the other hand, body fat redistribution may be found in the presence or absence of protease inhibitor therapy. Several factors, including age, length of time on therapy, nadir CD4 lymphocyte count, baseline plasma HIV RNA content, and others, have been shown to influence the presence of fat redistribution.
A sexual dimorphism in HIV-associated malnutrition has been demonstrated, with women losing greater relative amounts of body fat, compared with lean tissue, than are men. Several investigators have suggested that quantitative differences in fat redistribution also occur in HIV-infected men and women. In general, men were more likely than women to complain of fat depletion, especially in the arms, legs, and face, while women were more likely than men to complain of fat accumulation, especially in the abdomen and breasts. However, those studies were based largely on subjective self-report and did not include objective measurements of body fat content or comparison with healthy controls.
While the ability of self-report to accurately assess fat redistribution has been validated for epidemiologic studies in HIV-negative individuals, its clinical utility is less well accepted. In fact, one study documented discrepancies between subjective and objective estimates of change in body fat distribution as a result of switching antiretroviral agents. Such distinctions are important, since metabolic alterations as well as clinical outcomes appear to be related to absolute changes, rather than relative ones, in the sizes of fat compartments.
The purpose of this study was to compare differences between the sizes of body fat compartments in healthy controls and HIV-infected men and women with and without self-reported changes in body shape. The sizes of the VAT and SAT compartments were determined by whole body MRI scanning, and the results were compared with those of controls using a case-control analysis.
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