ABSTRACT
OBJECTIVE: This study aimed to compare BMI trajectories from childhood to early adulthood in those with overweight and/or obesity versus severe obesity. METHODS: Longitudinal BMI values (2,542 measurements) were calculated from measured heights and weights for 103 children, adolescents, or young adults with overweight, obesity, or severe obesity. Segmented regression with splines was used to model BMI trajectories. RESULTS: Sixty-nine participants were classified as ever having severe obesity versus 34 who never had severe obesity. Trajectories and slopes did not differ by sex or race/ethnicity. Compared with those who never had severe obesity, BMI was higher in the group with severe obesity at all ages, and BMI slope was higher for those with severe obesity at age 14 (P = 0.002), with peak slope occurring later (18 years vs. 16 years) and higher (4.5 ± 0.5 kg/m2 /y vs. 2.9 ± 0.5 kg/m2 /y; P < 0.02). In the group without severe obesity, BMI fell below zero by the mid-20s (-0.3 ± 0.6 kg/m2 /y); in those with severe obesity, BMI slope never reached zero (0.9 ± 0.5 kg/m2 /y). CONCLUSIONS: Youth with severe obesity, compared with their peers without, started with higher BMIs, had more rapid rates of BMI increase beginning at age 14, as well as a higher peak and longer period of increase, and never achieved weight stabilization.
Subject(s)
Adolescent Development , Body Mass Index , Child Development , Obesity, Morbid/physiopathology , Adolescent , Child , Child, Preschool , Female , Humans , Infant , Longitudinal Studies , Male , Obesity , Overweight , Young AdultABSTRACT
Frequency-dependent, complex refractive indices for oleic acid in the mid-infrared have been retrieved from aerosol extinction spectroscopy from 750 to 5000 cm(-1). The major absorption bands can be attributed to the relevant vibrational modes of the acid, including those that originate with the hydrogen bond induced dimerization through the carboxylic group. The newly reported indices for oleic acid are used to investigate the optical properties of model core-shell aerosols formed by coating a water droplet with a layer of oleic acid. The ability of a non-linear least-squares program to retrieve the structural parameters for core-shell particles is also explored. The initial results indicate that these parameters can be determined for such aerosols as long as the particles give rise to a sufficient amount of scattering in their extinction spectra. Low-scattering spectra, however, can yield suspicious results. Some limits on the application of the retrieval procedure to particles observed in the field are also discussed.
