Relationship of masked obesity to self-reported lifestyle habits, ideal body image, and anthropometric measures in Japanese university students: A cross-sectional study

IntroductionMasked obesity (MO) is defined as a normal body mass index (BMI) with a high body fat percentage (%BF), and is associated with the onset of lifestyle-related diseases. However, little is known about the current status of MO. Therefore, we investigated the relationship of MO to physical characteristics and lifestyle habits among Japanese university students.MethodsBetween 2011 and 2019, we conducted a survey of 10,168 males and 4,954 females with BMI within the normal range (18.5 ≤ BMI < 25 kg/m2). MO was defined as %BF ≥ 20% in males and %BF ≥ 30% in females. Students completed a questionnaire containing items about lifestyle habits. Systolic and diastolic blood pressures were measured, and hypertension was defined as systolic above 140 mmHg and/or diastolic blood pressure above 90 mmHg. A multivariate logistic regression analysis was performed to evaluate the relationships as follows: the relationship of masked obesity to self-reported lifestyle habits, ideal body image, and anthropometric measures; the relationship between hypertension and body indices.ResultsThe proportion of students with MO in 2019 was 13.4% in males and 25.8% in females, and the proportion of females increased over time. MO was associated with desire for weight loss (odds ratio, 95% confidence interval: 1.76, 1.53-2.02), intake of five macronutrients (0.79, 0.67-0.93), rice and wheat intakes (1.22, 1.01-1.47), sleep duration of < 7hr (0.85, 0.74-0.98), and exercise habit (0.71, 0.63-0.81) in males; and with balanced diet intake (0.79, 0.64-0.99) and exercise habit (0.65, 0.51-0.82) in females. There was a significant association of MO with hypertension in males (1.29, 1.09-1.53).ConclusionThe percentage of female students with MO increased during the study period, and in males, MO may be a risk factor for hypertension. These results suggest that intervention for MO is needed in Japanese university students.