Differential Associations between Weight Status (Obesity, Overweight, and Underweight) and Substance Use in Young Adulthood

Background Past evidence suggests obesity co-occurs with tobacco/nicotine, cannabis, and alcohol use in young adulthood, but whether this relationship extends to nicotine or cannabis vaping is unclear. Furthermore, differential relationships between substance use and specific weight status categories (obesity, overweight, and underweight) have not been assessed. This study assessed prevalence of tobacco/nicotine, cannabis, and alcohol use by weight status categories in young adulthood. Methods Of the 1322 young adults (18-29 years; 20.5 +/- 2.3 years; 63% female; 42% Hispanic/Latino/a/x, 30% Asian-American/Asian, 18% Caucasian/White, 7% Multiracial, and 2% African-American/Black) from a public, urban university were surveyed on their health-risk behaviors in the spring and fall of 2021. Results Multinomial logistic regression models assessed six-month follow-up substance use prevalence (never, lifetime but no past 30-d use, and past 30-d use) by baseline weight status (obese, overweight, underweight; reference: healthy weight). Obesity predicted lower odds of past 30-d nicotine vaping (aOR [95% CI] = 0.27 [0.08-0.92]). Overweight predicted higher odds of lifetime combustible cannabis (aOR [95% CI] = 1.58 [1.08-2.30]) and past 30-d binge drinking (aOR [95% CI] = 1.79 [1.12-2.85]). Underweight was associated with lower odds of lifetime cannabis vaping (aOR [95% CI] = 0.35 [0.12-0.99]) and combustible cannabis (aOR [95% CI] = 0.38 [0.16-0.87]). Conclusions Differential relationships between obesity and overweight on tobacco/nicotine, cannabis, and alcohol use suggest greater specificity is needed when evaluating relationships between higher weight status and substance use. It appears that overweight young adults may be at higher risk of substance use than obese young adults. Greater efforts to consider multiple weight status groups, not just obese, may have significant implications for tobacco/nicotine prevention and intervention efforts targeting vulnerable populations.