Health Behavior and Metabolic Risk Factors Associated with Normal Weight Obesity in Adolescents

To explore health behaviors and metabolic risk factors in normal weight obese (NWO) adolescents compared with normal weight lean (NWL) peers.

A cross-sectional study of 18-year-old students (n = 182, 47% female) in the capital area of Iceland, with body mass index within normal range (BMI, 18.5-24.9 kg/m2). Body composition was estimated via dual energy X-ray absorptiometry, fitness was assessed with maximal oxygen uptake (VO2max) during treadmill test, dietary intake through 24-hour recall, questionnaires explained health behavior and fasting blood samples were taken. NWO was defined as normal BMI and body fat >17.6% in males and >31.6% in females.

Among normal weight adolescents, 42% (n = 76) were defined as NWO, thereof 61% (n = 46) male participants. Fewer participants with NWO were physically active, ate breakfast on a regular basis, and consumed vegetables frequently compared with NWL. No difference was detected between the two groups in energy- and nutrient intake. The mean difference in aerobic fitness was 5.1 ml/kg/min between the groups in favor of the NWL group (p<0.001). NWO was positively associated with having one or more risk factors for metabolic syndrome (Odds Ratio OR = 2.2; 95% confidence interval CI: 1.2, 3.9) when adjusted for sex. High waist circumference was more prevalent among NWO than NWL, but only among girls (13% vs 4%, p = 0.019).

High prevalence of NWO was observed in the study group. Promoting healthy lifestyle with regard to nutrition and physical activity in early life should be emphasized regardless of BMI.