Flannagan KS, et al. - Researchers evaluated the correlation between serum polyunsaturated fatty acids (PUFA) biomarkers in childhood and change in body mass index (BMI)-for-age Z scores (BMIZ) through adolescence. Participants were 418 children from Santiago, Chile, in whom, serum PUFA was quantified at ages 5 and 10 years. At 5, 10, and 16 years, BMI was measured. By fitting growth curves from mixed effects models, they compared BMIZ change through age 16 years between quartiles of PUFA at 5 and 10 years and PUFA change 5–10 years. At age 5 years, an inverse association of serum docosahexaenoic acid with BMIZ change from ages 5 to 16 years was identified. At age 10 years, a nonlinear positive association of arachidonic acid (AA) with BMIZ change from ages 10 to 16 years was reported. In this study, a link between serum long-chain n-3 PUFA in middle childhood and less BMI gain through adolescence was shown. Greater BMI gain was reported in relation to AA and Δ5-desaturase activity.