Physical activity monitoring in extremely obese adolescents from the Teen-LABORATORIES study.

BACKGROUND: The accuracy of physical activity (PA) monitors to discriminate between PA, sedentary behavior, and nonwear in extremely obese (EO) adolescents is unknown. METHODS: Twenty-five subjects (9 male/16 female; age = 16.5 ± 2.0 y; BMI = 51 ± 8 kg/m2) wore 3 activity monitors (StepWatch [SAM], Actical [AC], Actiheart [AH]) during a 400-m walk test (400MWT), 2 standardized PA bouts of varying duration, and 1 sedentary bout. RESULTS: For the 400MWT, percent error between observed and monitor-recorded steps was 5.5 ± 7.1% and 82.1 ± 38.6% for the SAM and AC steps, respectively (observed vs. SAM steps: -17.2 ± 22.2 steps; observed vs. AC steps: -264.5 ± 124.8 steps). All activity monitors were able to differentiate between PA and sedentary bouts, but only SAM steps and AH heart rate were significantly different between sedentary behavior and nonwear (P < .001). For all monitors, sedentary behavior was characterized by bouts of zero steps/counts punctuated by intermittent activity steps/counts; nonwear was represented almost exclusively by zero steps/counts. CONCLUSION: Of all monitors tested, the SAM was most accurate in terms of counting steps and differentiating levels of PA and thus, most appropriate for EO adolescents. The ability to accurately characterize PA intensity in EO adolescents critically depends on activity monitor selection.

Dietary assessment of adolescents undergoing laparoscopic Roux-en-Y gastric bypass surgery: macro- and micronutrient, fiber, and supplement intake.

BACKGROUND: Extremely obese adolescents are increasingly undergoing bariatric procedures, which restrict dietary intake. However, as yet, no data are available describing the change in caloric density or composition of the adolescent bariatric patient's diet pre- and postoperatively. Our objective was to assess the 1-year change in the dietary composition of adolescents undergoing bariatric surgery at a tertiary care children's hospital. METHODS: A total of 27 subjects (67% female, 77% white, age 16.7 ± 1.4 yr, baseline body mass index 60.1 ± 14.1 kg/m(2)) were prospectively enrolled into an observational cohort study 1 month before undergoing laparoscopic Roux-en-Y gastric bypass from August 2005 to March 2008. The 3-day dietary intake was recorded at baseline (n = 24) and 2 weeks (n = 16), 3 months (n = 11), and 1 year (n = 9) postoperatively. The dietary record data were verified by structured interview and compared with the Dietary Reference Intake values for ages 14-18 years. RESULTS: By 1 year after surgery, the mean caloric intake, adjusted for body mass index was 1015 ± 182 kcal/d, a 35% reduction from baseline. The proportion of fat, protein, and carbohydrate intake did not differ from baseline. However, the protein intake was lower than recommended postoperatively. The calcium and fiber intake was also persistently lower than recommended. Calcium and vitamin B(12) supplementation increased the likelihood of meeting the daily minimal recommendations (P ≤ .02). CONCLUSION: At 1 year after Roux-en-Y gastric bypass, the adolescents' caloric intake remained restricted, with satisfactory macronutrient composition but a lower than desirable intake of calcium, fiber, and protein.