Heavy injection drug use is associated with lower percent body fat in a multi-ethnic cohort of HIV-positive and HIV-negative drug users from three U.S. cities.

BACKGROUND: The clinical implications of lower body weight in drug using populations are uncertain given that lower mean weights may still fall within the healthy range.
OBJECTIVES: To determine the effect of type, mode and frequency of drug use on underlying body composition after accounting for differences in body shape and size.
METHODS: We conducted a cross-sectional analysis of 511 participants from the Tufts Nutrition Collaborative (TNC) Study. Data included measures of body composition, a 24-hour dietary recall, and a detailed health history and lifestyle questionnaire. Multivariate regression analysis was used to determine the independent effect of drug use on percent body fat (BF) after adjusting for BMI and waist circumference.
RESULTS: Heavy injection drug users (IDUs) had a 2.6% lower percent BF than non-users after adjusting for BMI, waist circumference, and other confounders. (p = 0.0006). Differences in percent BF were predominantly due to higher lean mass, rather than lower fat mass. Cocaine and heroin had similar effects on body composition.
CONCLUSIONS: In the U.S., where the general population is prone to over-nutrition, the average percent BF for heavy injectors does not fall into a range low enough to suggest harmful effects. However, in populations with substantial levels of under-nutrition, small differences in percent BF among drug users will have a greater impact on health status. SCIENTIFIC SIGNIFICANCE: Differences in BMI, weight and body composition are not always straightforward. Accounting for underlying nutritional status and relative differences in fat and FFM is critical when interpreting results. diagnosed patients and prevent them from returning to prison.