Adolescent obesity: Biochemical and dietary disparities in U.S. youth

Adolescence is a critical period of growth with elevated nutritional demands, yet many U.S. adolescents fail to meet recommended dietary intakes. This study analyzed data from three NHANES cycles (2013-2018) to assess obesity trends among adolescents aged 12-18, compare dietary intake by BMI, and evaluate nutritional biomarkers.

This retrospective observational study analyzed data from three NHANES cycles to estimate obesity prevalence among U.S. adolescents aged 12-18 years. Dietary intake and blood concentrations of micro- and macronutrients were compared between adolescents with and without obesity. Obesity was defined as BMI ≥95th percentile per CDC growth charts. Nutrient intake was assessed against Estimated Average Requirement (EAR) and Adequate Intake (AI) benchmarks, and biomarker levels were evaluated using established clinical thresholds. All statistical analyses were conducted using SAS version 9.4 and SAS Enterprise Guide version 8.3.

Obesity prevalence increased slightly from 20.3% to 21.3% across cycles. Among all dietary intake variables analyzed, only one demonstrated a statistically significant difference between those with obesity and those without. The adolescents with obesity were significantly more likely to have protein intakes below the EAR (50.3% vs. 22.9%, P < 0.001). Over half of all adolescents failed to meet recommended intake levels for several nutrients, regardless of their BMI categories. The blood biomarker analysis revealed significantly lower levels of vitamin D, vitamin C, serum iron, albumin, and MCV in those with obesity, alongside higher levels of total protein, globulin, and hs-CRP (P ≤ 0.05). The prevalence of low vitamin D, low hemoglobin, low MCV, and iron deficiency anemia was also significantly higher in the group with obesity.

This study reveals that despite similar caloric intakes, adolescents with obesity exhibited higher rates of nutrient deficiencies and markers of inflammation. This work underscores the importance of recognizing nutrition gaps in adolescent care.