Body composition in anorexia nervosa: Meta-analysis and meta-regression of cross-sectional and longitudinal studies

Objective Clinically, anorexia nervosa (AN) presents with altered body composition. We quantified these alterations and evaluated their relationships with metabolites and hormones in patients with AN longitudinally. Method In accordance with PRISMA guidelines, we conducted 94 meta-analyses on 62 samples published during 1996-2019, comparing up to 2,319 pretreatment, posttreatment, and weight-recovered female patients with AN with up to 1,879 controls. Primary outcomes were fat mass, fat-free mass, body fat percentage, and their regional distribution. Secondary outcomes were bone mineral density, metabolites, and hormones. Meta-regressions examined relationships among those measures and moderators. Results Pretreatment female patients with AN evidenced 50% lower fat mass (mean difference [MD]: -8.80 kg, 95% CI: -9.81, -7.79, Q = 1.01 x 10(-63)) and 4.98 kg (95% CI: -5.85, -4.12, Q = 1.99 x 10(-28)) lower fat-free mass, with fat mass preferentially stored in the trunk region during early weight restoration (4.2%, 95% CI: -2.1, -6.2, Q = 2.30 x 10(-4)). While the majority of traits returned to levels seen in healthy controls after weight restoration, fat-free mass (MD: -1.27 kg, 95% CI: -1.79, -0.75, Q = 5.49 x 10(-6)) and bone mineral density (MD: -0.10 kg, 95% CI: -0.18, -0.03, Q = 0.01) remained significantly altered. Discussion Body composition is markedly altered in AN, warranting research into these phenotypes as clinical risk or relapse predictors. Notably, the long-term altered levels of fat-free mass and bone mineral density suggest that these parameters should be investigated as potential AN trait markers. ResumenObjetivo Clinicamente, la anorexia nervosa (AN) se presenta con alteraciones en la composicion corporal. Cuantificamos estas alteraciones y evaluamos longitudinalmente su relacion con metabolitos y hormonas en pacientes con AN. Metodo De acuerdo con las pautas PRISMA, realizamos 94 meta-analisis en 62 muestras publicadas entre 1996-2019, comparando hasta 2,319 pacientes mujeres en pre-tratamiento, post-tratamiento, y recuperadas en base al peso con hasta 1,879 controles. Las principales medidas fueron masa grasa, masa libre de grasa, porcentaje de grasa corporal y su distribucion regional. Las medidas secundarias fueron densidad mineral osea, metabolitos y hormonas. Las meta-regresiones examinaron las relaciones entre esas medidas y moderadores. Resultados Las pacientes femeninas con AN pre-tratamiento mostraron un 50% menos de masa grasa (MD: -8.80 kg, CI 95%: -9.81, -7.79, Q = 1.01 x 10(-)(63)) y 4.98 kg (CI 95%: -5.85, -4.12, Q = 1.99 x 10(-)(28)) menos de masa libre de grasa, con masa grasa preferentemente almacenada en la region del tronco durante la recuperacion temprana del peso (4.2%, CI 95%: -2.1, -6.2, Q = 2.30 x 10(-)(4)). Aunque la mayoria de los rasgos regresaron a los niveles vistos en los controles sanos despues de la restauracion del peso, la masa libre de grasa (MD: -1.27 kg, CI 95%: -1.79, -0.75, Q = 5.49 x 10(-)(6)) y la densidad mineral osea (MD: -0.10 kg, CI 95%: -0.18, -0.03, Q = 0. 01) permanecieron significativamente alteradas. Discusion La composicion corporal es marcadamente alterada en la AN, lo que garantiza la investigacion en estos fenotipos como predictores de riesgo clinico o de recaida. Notablemente, la alteracion a largo plazo de los niveles de masa libre de grasa y densidad mineral osea sugieren que estos parametros debe ser investigados como potenciales rasgos indicadores de AN.