Effect of highly active antiretroviral therapy on fat, lean, and bone mass in HIV-seropositive men and women

BACKGROUND

Alterations in body composition have been reported in HIV-positive adults receiving highly active antiretroviral therapy (HAART), but the magnitude and potential determinants of these changes are unclear.

OBJECTIVE

We compared total and regional body composition, as measured by dual-energy X-ray absorptiometry, in 203 HIV-positive men and 62 HIV-positive women according to HAART.

DESIGN

This was a cross-sectional analysis of a cohort study of nutrition and HIV infection.

RESULTS

After adjustment for age, weight, race, and exercise habits, total weight and fat mass did not differ significantly in men or women by HAART. Trunk fat was greater in men (1.0 kg; P < 0.001) and women (1.4 kg; P = 0.005) and leg fat was lower in men (-1.0 kg; P < 0.001) and women (-1.5 kg, P = 0.005) receiving HAART than in those not. This corresponded to a greater percentage of total fat mass located in the trunk (men: 7.5%, P < 0.001; women: 5.1%, P = 0.02). Lean mass was also greater with longer duration of HAART in men (P < 0.002). In men receiving HAART, total and regional bone mineral content were less than in the men not receiving HAART (P < 0.001). These effects increased with longer duration of HAART. Protease inhibitors were associated with the largest differences in regional fat.

CONCLUSIONS

HAART is associated with redistribution of fat mass from the legs to the trunk, despite no significant differences in total fat mass or weight. In men, HAART is also associated with a reduction in bone mineral content, suggesting that HAART increases the risk of central obesity and osteoporosis.

Do patients with nonmetastatic non-small cell lung cancer demonstrate altered resting energy expenditure?

BACKGROUND

The cancer cachexia syndrome occurs in patients with non-small cell lung cancer (NSCLC) and includes elevated resting energy expenditure (REE). This increase in REE leads to weight loss, which in turn confers a poor prognosis. This study was undertaken to determine whether the cancer cachexia syndrome occurs in patients with nonmetastatic NSCLC.

METHODS

In this case-control study, 18 patients with nonmetastatic NSCLC (stages IA to IIIB) were matched to healthy controls on age (+/- 5 years), gender, and body mass index (+/- 3 kg/m2). Only 4 cancer patients had experienced > 5% weight loss. Cancer patients and controls were compared on the basis of: (1) unadjusted REE, as measured by indirect calorimetry; (2) REE adjusted for lean body mass, as measured by dual x-ray absorptiometry; (3) REE adjusted for body cell mass, as measured by potassium-40 measurement; and (4) REE adjusted for total body water, as measured by tritiated water dilution.

RESULTS

We observed no significant difference in unadjusted REE or in REE adjusted for total body water. However, with separate adjustments for lean body mass and body cell mass, cancer patients manifested an increase in REE: mean difference +/- standard error of the mean: 140+/-35 kcal/day (p = 0.001) and 173+/-65 kcal/day (p = 0.032), respectively. Further adjustment for weight loss yielded similarly significant results.

CONCLUSIONS

These results suggest that the cancer cachexia syndrome occurs in patients with nonmetastatic NSCLC and raise the question of whether clinical trials that target cancer cachexia should be initiated before weight loss.

Chemical and elemental analysis of humans in vivo using improved body composition models

Six chemical compartments [water, protein, mineral (osseus and cellular), glycogen, and fat] consisting of 11 elements (N, C, Ca, Na, Cl, K, H, P, O, S, and Mg) comprise greater than or equal to 99% of body weight in living humans. The combination of three neutron-activation systems, whole body 40K counting, and 3H2O dilution at Brookhaven National Laboratory now potentially makes it possible to quantify greater than or equal to 96% of the chemical and elemental determinants of body weight in vivo. The aims of the present study were 1) to develop 6- and 11-compartment chemical and elemental models, respectively, and 2) to evaluate these models in a group of 20 healthy adults. Results demonstrated that body weight estimated from either chemical or elemental components was highly correlated with (both r = 0.97, P less than 0.001) and on average differed by less than 4% from actual body weight. The compartmental results obtained using the chemical model were also evaluated by comparing calculated and actual body density (Db) estimated by underwater weighing. Calculated Db [1.041 +/- 0.017 (SD) g/ml] agreed closely and was highly correlated with actual Db (1.039 +/- 0.018 g/ml; r = 0.82; P less than 0.001). Hence a near-complete chemical and elemental analysis of living human subjects is now possible and, with potential future refinements, represents an important opportunity to quantify the effects of gender, aging, and ethnic status on body composition.

Measuring body fat: calibrating the rulers. Intermethod comparisons in 389 normal Caucasian subjects

A systematic study of 389 normal Caucasians stratified for sex and age compared all of the traditional methods for measuring fat: body water, underwater weighing, body potassium, and anthropometrics and the newer methods of dual-photon absorptiometry, bioimpedance analysis, and total body electrical conductivity. Measurements by all methods are highly intercorrelated, but methods differences show the population means for fat percent to range from 26 to 35% of body weight across eight methods. All methods show increasing fat (as % body weight) with age in both sexes but vary in secular slope. The goal of this report is to provide direct translations between each of the eight methods. Intermethod comparison equations are given as simple linear regressions by using each method both as dependent and independent variable for each sex, permitting translation for results by any method to any other.

Chemical determination of human body density in vivo: relevance to hydrodensitometry

A chemical approach to establishing human body density in vivo was developed by combining recently developed noninvasive methods. Four compartments were measured: protein (P; prompt-gamma neutron activation), water (A; 3H2O dilution), mineral (M; dual-photon absorptiometry and delayed-gamma neutron activation), and fat (F; dual-photon absorptiometry). By this model body weight is equal to P + A + M + F. This approach was applied to 13 healthy adults (8 females and 5 males). The four compartments accounted for greater than 97% actual body weight. Calculated density based upon composition agreed within 0.6 +/- 0.4% (mean +/- SD) with density (D) measured by hydrodensitometry [calculated D (g/cc) = 0.86 measured D +0.15; r = 0.94, p less than 0.001]. The average calculated lean (P + A + M) density of 1.096 +/- 0.007 g/cc agreed closely with three classic human cadaver studies (1.100 g/cc). This multicompartment approach provides a new opportunity to estimate human body density in vivo and to refine body composition methods based upon an assumed but inadequately validated constant lean density.

Body composition in elderly subjects: a critical appraisal of clinical methodology

Body composition measurements are integral to nutritional assessment of elderly subjects. The validity of methods available for partitioning body weight into its tissue or chemical subfractions in the geriatric population is of primary importance. Until recently verifying the accuracy of body composition techniques in vivo was limited by prevailing technology. New advances such as neutron activation analysis, neutron inelastic scattering, and dual photon absorptiometry now promise to overcome these earlier limitations. With these new tools investigators can now examine critical underlying assumptions related to body composition assessment in elderly subjects. This review highlights the need and opportunities for future research in this area.