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Abstract Background The effect of exercise on subjective appetite and short-term food intake has received little investigation in children. Despite a lack of reported evaluation of short-duration activity programs, they are currently being implemented in schools as a means to benefit energy balance. The purpose of this study was to determine the effect of duration of exercise at the ventilation threshold (VeT) on subjective appetite and short-term food intake in normal weight boys and girls aged 9 to 14 years. Methods On 4 separate mornings and in random order, boys (n = 14) and girls (n = 15) completed 2 rest or 2 exercise treatments for 15 (short-duration; SD) or 45 min (long-duration; LD) at their previously measured VeT, 2 h after a standardized breakfast. Subjective appetite was measured at regular intervals during the study sessions and food intake from a pizza meal was measured 30 min after rest or exercise. Results An increase in average appetite, desire to eat, and hunger (p < 0.05) was attenuated by SD exercise, but was further increased (p < 0.05) by LD exercise. However, food intake after SD and LD exercise was similar to after rest in both boys and girls (p = 0.55). The energy cost of SD and LD exercise resulted in a lower net energy balance compared to resting during the study measurement period in boys (SD: Δ = -418 ± 301 kJ; LD: Δ = -928 ± 196 kJ) and in girls (SD: Δ = -297 ± 105 kJ; LD: Δ = -432 ± 115 kJ). Conclusion Neither SD nor LD exercise at the VeT increased short-term food intake and SD exercise attenuated increases in appetite. Thus, SD exercise programs in schools may be an effective strategy for maintaining healthier body weights in children.

Summary Background & aims Severe obesity in children and adolescents is now a serious global health concern. Accurate measurements of resting energy expenditure (REE) is a key foundation for successful obesity treatment. Clinical dietitians rely heavily on measured or calculated REE to tailor dietary interventions. Indirect calorimetry (IC) is the gold standard for measuring REE. However, predictive resting energy expenditure (PREE) equations are commonly used when IC is unavailable due to cost or practicality. PREE equations differ based on variables such as age, gender, weight, and height and selecting the most accurate PREE for an individual is crucial to avoid over or underestimation of energy requirements. Published studies investigating the accuracy of PREE equations in obese children and adolescents have reported inconsistent findings, which likely result from heterogeneity in the patient populations studied. Accordingly, this study aimed to (a) assess the accuracy of the published PREE equations in a group of severely obese (SO) adolescents using IC measurement, and (b) determine if there is a BMI threshold at which the PREE equations become less accurate. Methods SO adolescents were studied using IC. REE was calculated using nine commonly used PREE equations. Generalized linear regression equations were used to compare absolute and relative differences between calculated and measured REE (MREE) for each PREE equation. Accuracy was calculated as the percentage of subjects with PREE values within 10 percent of MREE. Results 226 SO adolescents (mean ± SD age: 15.9 ± 1.9 years; weight: 126.9 ± 24.5 kg; BMI: 44.9 ± 8.1 kg/m 2 ) participated. Mean MREE was 2163 ± 443 kcal/d. PREE calculated by the Mifflin equation was the only equation without a statistically significant bias compared to MREE (mean bias of −23 ± 307 kcal/d; p = 0.26). Mifflin was also the most accurate with 61% of individuals within ±10% of MREE. PREE equations accuracy was not associated with degree of BMI elevation (31–69 kg/m 2 ). Conclusions In adolescents with severe obesity, the Mifflin equation best predicts REE. This should be the equation applied when using PREE to optimize nutritional care in this population. [ABSTRACT FROM AUTHOR]

Objective Glucagon-like peptide-2 (GLP-2) is co-secreted with GLP-1 from gut endocrine cells, and both peptides act as growth factors to expand the surface area of the mucosal epithelium. Notably, GLP-2 also enhances glucose and lipid transport in enterocytes; however, its actions on control of amino acid (AA) transport remain unclear. Here we examined the mechanisms linking gain and loss of GLP-2 receptor (GLP-2R) signaling to control of intestinal amino acid absorption in mice. Methods Absorption, transport, and clearance of essential AAs, specifically lysine, were measured in vivo by Liquid Chromatography triple quadrupole Mass Spectrometry (LC-MS/MS) and ex vivo with Ussing chambers using intestinal preparations from Glp2 r +/+ and Glp2r − / − mice. Immunoblotting determined jejunal levels of protein components of signaling pathways (PI3K-AKT, and mTORC1-pS6-p4E-BP1) following administration of GLP-2, protein gavage, and rapamycin to fasted Glp2 r +/+ and Glp2r − / − mice. Expression of AA transporters from full thickness jejunum and 4F2hc from brush border membrane vesicles (BBMVs) was measured by real-time PCR and immunoblotting, respectively. Results Acute administration of GLP-2 increased basal AA absorption in vivo and augmented basal lysine transport ex vivo . GLP-2-stimulated lysine transport was attenuated by co-incubation with wortmannin, rapamycin, or tetrodotoxin ex vivo . Phosphorylation of mTORC1 effector proteins S6 and 4E-BP1 was significantly increased in wild-type mice in response to GLP-2 alone, or when co-administered with protein gavage, and abolished following oral gavage of rapamycin. In contrast, activation of GLP-1R signaling did not enhance S6 phosphorylation. Disruption of GLP-2 action in Glp2r −/− mice reduced lysine transport ex vivo and attenuated the phosphorylation of S6 and 4E-BP1 in response to oral protein. Moreover, the expression of cationic AA transporter slc7a9 in response to refeeding, and the abundance of 4F2hc in BBMVs following protein gavage, was significantly attenuated in Glp2r −/− mice. Conclusions These findings reveal an important role for GLP-2R signaling in the physiological and pharmacological control of enteral amino acid sensing and assimilation, defining an enteroendocrine cell-enterocyte axis for optimal energy absorption. [ABSTRACT FROM AUTHOR]

There are few reported estimates of amino acid (AA) kinetics in adult mammals and none exist in adult dogs. The study objectives were to evaluate the use of oral isotope delivery in contrast to the more commonly used intravenous (IV) delivery to estimate AA kinetics in adult dogs and to estimate splanchnic extraction and gastric emptying using a commonly accepted mathematical model. Dogs received 25 × 1/2-hourly meals (13 g/kg BW/day) and either an oral or IV bolus of l-[1-13C]Phe (12 mg/kg BW). Blood samples were taken immediately before each feeding. Concentrations of plasma Phe were measured using liquid chromatography-tandem mass spectrometry. There were no differences in baseline plasma Phe concentrations (34 μ m ± 0.61), Phe distribution volume, Phe pool size and rate constants between dogs when the tracer was administered IV or orally (p > 0.25). Decay curve for plasma l-[1-13C]Phe differed between IV and oral dosing protocols with IV dosing fit best using a two-compartment model. Phe disappeared from plasma at a mean rate of 2.8%/min. Estimates of gastric emptying and splanchnic extraction did not differ based on oral or IV tracer dosing when the decay curves were fit with the two-compartment model (p > 0.40). The half-life for gastric emptying was 18 min, and first-pass Phe extraction by the splanchnic bed was 24% of the dietary Phe. These results suggest that oral isotope dosing can be used as an alternative to IV isotope dosing in studies that utilize a primed, constant dosing approach to measure protein and amino acid kinetics. [ABSTRACT FROM AUTHOR]