Much research has focused on the proximate determinants of weight gain and obesity for adolescents, but not much information has emerged on identifying which adolescents might be at risk or on prevention. This research focuses on a distal determinant of teenage weight gain, namely changes in the economy, which may help identify geographical areas where adolescents may be at risk and may provide insights into the mechanisms by which adolescents gain weight. This study uses a nationally representative sample of individuals, between 15 and 18 years old from the 1997 US National Longitudinal Survey of Youth, to estimate a model with state and year fixed effects to examine how within-state changes in the unemployment rate affect four teenage weight outcomes: an age- and gender-standardized percentile in the body-mass-index distribution and indicators for being overweight, obese, and underweight. I found statistically significant estimates, indicating that females gain weight in weaker economic periods and males gain weight in stronger economic periods. Possible causes for the contrasting results across gender include, among other things, differences in the responsiveness of labor market work to the economy and differences in the types of jobs generally occupied by female and male teenagers.