No differences in the body fat after violating core bioelectrical impedance measurement assumptions.

OBJECTIVE: It is unclear to what degree acutely violating bioelectrical impedance analysis (BIA) measurement assumptions will alter the predicted percent fat mass (%FM) and whether this differs by sex or body mass index (BMI). METHODS: %FM was assessed under control, dehydration, exercise, water, food intake and non-voided bladder conditions with three BIA devices (Tanita: BC-418, TBF-314, & Omron HBF-306CN) for men (n = 23, age: 24.0 ± 5.2 years old) and women (n = 17, age: 22.5 ± 3.4 years old) separately. RESULTS: For all BIA devices, there were no differences in the %FM values between the control and the other conditions in men or women (- 1.9 to 0.4%, p > 0.05). Across the three devices and five conditions, 97% of %FM tests returned values within 5% of control (2 tests), and 86% of tests were within 2% of control despite violating an assumption. The errors were greatest with dehydration and women were more likely to have a %FM difference greater than 2% than men with dehydration using the hand-to-foot device (Tanita TBF-314: 59% versus 9%). There were no differences in %FM between control and the conditions when examined by BMI (overweight/obesity: - 2.8 to 0.1% and normal weight: - 1.7 to 0.5%; BMI*trial, p = 0.99). CONCLUSION: %FM estimates were similar despite acutely violating the preliminary measurement BIA assumptions across a range of different BMIs. The minor variations in %FM are smaller than what would be expected with day-to-day variability or weight loss intervention but may be larger in women than men.

Real-World Effectiveness of Pharmaceutical Smoking Cessation Aids: Time-Varying Effects.

BACKGROUND: There are a limited number of studies that have examined the real-world effectiveness of smoking cessation aids and relapse longitudinally in population-representative samples. This study examines the association between use of nicotine gum, patch, bupropion, and varenicline and time to relapse as well as any changes in the association with increased length of abstinence. METHODS: Data of 1821 current adult smokers (18+) making their first serious quit attempt were compiled from 4504 individuals enrolled in the Ontario Tobacco Survey, a representative telephone survey of Ontario adults, which followed smokers every 6 months for up to 3 years. Use of cessation aids at the time of initial report of a quit attempt was analyzed. A flexible parametric survival model was developed to model length of abstinence, controlling for potential confounders. RESULTS: The best fit model found knots at 3, 13, 43, and 212 days abstinent, suggesting different rates of relapse in the periods marked by those days. Use of the patch and varenicline was associated with lower rates of relapse, but no positive effect was found for bupropion or nicotine gum. The effectiveness of the patch reversed in effect after the first month of abstinence. CONCLUSIONS: This study is one of few reports of long-term quitting in a population-representative sample and demonstrates that the effectiveness of some pharmacological cessation aids (the patch and varenicline can be seen in a population sample). Previous failures in real-world studies of the effectiveness of smoking cessation aids may reflect differences in the products individuals use and differences in the timing of self-reported cessation. IMPLICATIONS: While a large number of randomized controlled trials have shown the efficacy of many pharmaceutical smoking cessation aids, evidence of their effectiveness in observational studies in the real world is ambiguous. This study uses a longitudinal cohort of a representative sample of smokers to show that the effectiveness of pharmaceutical cessation aids can be demonstrated in real-world use situations, but effectiveness varies by product type and has time-varying effects.

Lifestyle and weight predictors of a healthy overweight profile over a 20-year follow-up.

OBJECTIVE: To examine whether changes in modifiable risk factors [physical activity, cardiorespiratory fitness (CRF), body weight, and diet composition] are associated with the transition to metabolically healthy overweight/obese (MHOW) versus metabolically abnormal overweight/obese. METHODS: Analysis included 1,358 adults [aged 25.0 (3.5) years] from the CARDIA study who were healthy at baseline and had overweight/obesity at follow-up. Participants with zero or one of the following six risk factors were classified as MHOW: elevated triglycerides, LDL, blood pressure, fasting glucose, and HOMA-insulin resistance and low HDL. RESULTS: Over the 20-year follow-up, the sample gained weight (BMI 24.5 to 31.1 kg/m(2) ), and the prevalence of MHOW was 47% at follow-up. After adjusting for changes in CRF, diet, and weight change, physical activity and macronutrient intake were not independently associated with MHOW (P > 0.05), while changes in CRF [fit-unfit: RR (95%) = 0.58, 0.52-0.66; unfit-unfit: RR = 0.67, 0.58-0.76, versus fit-fit] and weight [gain: RR (95%) = 0.54, 0.43-0.67; cycle: RR = 0.74, 0.57-0.94, versus stable] were independently associated with MHOW. CONCLUSIONS: Focusing on high CRF and strategies to limit weight gain may be important for individuals with overweight and obesity in early to mid-adulthood to maintain a metabolically healthy profile.