Onset of the Thermic Effect of Feeding (TEF): a randomized cross-over trial

<p>Abstract</p> <p>Background</p> <p>The purpose of this investigation was to identify the onset of the thermic effect of feeding (TEF) after ingestion of a high carbohydrate (CHO) and a high protein (PRO) 1255 kJ (300 kcal) drink.</p> <p>Methods</p> <p>Resting metabolic rate (RMR) and TEF were measured over 30-minute periods via indirect calorimetry using a ventilated hood technique. Eighteen subjects (7 men and 11 women) completed two randomized, double-blind trials. Data were collected in 1-minute measurement intervals. RMR was subtracted from TEF and the time of onset was obtained when two consecutive data points exceeded 5% and 10% of resting metabolic rate.</p> <p>Results</p> <p>At 5% above RMR the onset of TEF for CHO was 8.4 ± 6.2 minutes and was not different as compared to PRO, 8.6 ± 5.2 minutes (p = 0.77). Likewise, no differences were found with a 10% increase above RMR: CHO, 14.1 ± 7.5 min; PRO, 16.7 ± 6.7 min (p = 0.36). Several subjects did not show a 10% increase within 30-min.</p> <p>Conclusion</p> <p>We conclude that the onset of TEF is variable among subjects but is initiated within about 5 to 20-min for most subjects after ingestion of a 1255 kJ liquid meal. No differences were found between CHO or PRO liquid meals.</p

Comparison of gestational weight gain-related pregnancy outcomes in American primiparous and multiparous women1-3

Background: In Danish data, the tradeoffs between mother and infant in the risks of adverse pregnancy outcomes were reached at lower gestational weight gain (GWG) among multiparous than among primiparous women. It is unknown whether the same difference exists among American women. Objective: The objective was to determine whether these tradeoffs also differ by parity among women in a contemporary American birth cohort. Design: Data from 822 primiparous and 2055 multiparous American women who participated in the Infant Feeding Practices Study II (2005-2007), a national cohort study, were analyzed. Their selfreported GWG was divided into 4 categories (#10, .10 to ,15, 15 to ,20, and S20 kg). GWG-specific absolute adjusted risks for emergency cesarean delivery, birth of a small-for-gestational-age (SGA) or large-for-gestational-age (LGA) infant, and postpartum weight retention at±mo were estimated by multiple logistic regression analyses for women in 3 categories of prepregnancy body mass index. Results: Primiparous women gained more weight during pregnancy than did multiparous women (mean±SD: 15.9±6.9 compared with 13.5±6.2 kg; P < 0.0001). The absolute adjusted risk of postpartum weight retention rose steeply with increasing GWG among both primiparous and multiparous women. The risk of emergency cesarean delivery and of delivering LGA infants increased with increasing GWG only among multiparous women. The risk of SGA tended to decrease with increasing GWG in both parity groups. Conclusion: These findings extend the concept of a lower optimal GWG among multiparous than primiparous women to American women. © 2013 American Society for Nutrition

Assessing the Test–retest Repeatability of Insulin Resistance Measures: Homeostasis Model Assessment 2 and Oral Glucose Insulin Sensitivity

Background: Insulin resistance is commonly assessed using the homeostasis model assessment (HOMA) variants. HOMA is potentially insensitive to change because of its high coefficient of variation. The repeatability coefficient is an alternative means of assessing test repeatability. To be confident of clinical change, rather than biological variation, a subsequent test needs to differ from the former by more than the repeatability coefficient using the equation. Test 1 = Test 2 ± repeatability coefficient. The repeatability coefficients for measures of insulin resistance are unknown. Aim: To compare the repeatability coefficient of HOMA2 variants (Beta-cell function [%B], insulin sensitivity [%S], insulin resistance [IR]) to a dynamic measure of insulin resistance, and the oral glucose insulin sensitivity (OGIS) test. Setting: The raw data from a previously used data set were reanalysed. Methods: Glycaemic and insulinaemic tests were performed on 32 men and women both with (n = 10) and without type 2 diabetes (n = 22). From these data, eight fasting tests and three 50-g oral glucose tolerance tests were used to calculate HOMA2 and OGIS. The methods of Bland and Altman assessed repeatability. Results: Repeatability coefficients for all participants for the HOMA2 %B, %S and IR variants were 72.91, 189.75 and 0.9, which equates to 89%, 135% and 89% of their respective grand means. By contrast, OGIS had a repeatability coefficient of 87.13, which equates to 21% of the grand mean. Conclusion: Because of the high repeatability coefficient relative to the grand mean, use of HOMA2 measures for assessing insulin resistance in small population studies should be reconsidered