Leptin resistance in children with in utero exposure to maternal obesity and gestational diabetes.

BACKGROUND: Leptin resistance occurs with obesity, but it is unknown if individuals at risk for obesity develop leptin resistance prior to obesity. OBJECTIVE: Investigate whether leptin resistance is independent of weight status in children at risk for obesity due to intrauterine exposure to maternal obesity or gestational diabetes mellitus (GDM). METHODS: Mother-child dyads (N = 179) were grouped by maternal pregnancy weight and GDM status: (1) normal weight, no GDM; (2) overweight/obesity, no GDM; (3) overweight/obesity with GDM. Children (4-10 years) were further stratified by current body mass index (BMI) <85th or ≥85th percentile. Leptin resistance of children and mothers was calculated as fasting leptin/fat mass index. Two-way ANOVA was used to assess whether leptin concentrations and leptin resistance differed by current weight status or in utero exposure group, after adjusting for race, sex and Tanner stage. RESULTS: Children with a BMI ≥85th percentile had more leptin resistance than those with a BMI <85th percentile (p < 0.001), but leptin resistance did not differ by in utero exposure. Similarly, leptin resistance in women was associated with weight status and not prior GDM. CONCLUSIONS: Results suggest that leptin concentrations are associated with obesity but not risk for obesity based on in utero exposure to maternal obesity or GDM.

Associations of Maternal Prenatal Stress and Depressive Symptoms With Childhood Neurobehavioral Outcomes in the ECHO Cohort of the NICHD Fetal Growth Studies: Fetal Growth Velocity as a Potential Mediator.

OBJECTIVE: Maternal prenatal stress and mood symptoms are associated with risk for child psychopathology. Within the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) Fetal Growth Studies (ECHO-FGS), a racially and ethnically diverse cohort, we studied associations between prenatal stress and depressive symptoms with child neurobehavior, and potential mediation by fetal growth velocity (FGV) in low-risk pregnancies. METHOD: For 730 mother-child pairs, we had serial ultrasound measurements, self-reports of prenatal stress and depression, observations of child executive functions and motor skills from 4 to 8 years, and maternal reports of child psychiatric problems. We tested associations between prenatal stress and depressive symptoms with child neurobehavior in regression analyses, and associations with FGV in mixed effect models. Post hoc we tested severity of prenatal symptoms; FGV at 25th, 50th, and 75th percentiles; and moderation by biological sex and by race and ethnicity. RESULTS: Prenatal stress and depressive symptoms were associated with child psychiatric problems, and prenatal depressive symptoms with decrements in executive functions and motor skills, especially in biological male children. Neither prenatal stress nor depressive symptoms were associated with FGV. CONCLUSION: In one of the largest cohorts with observed child outcomes, and the first with broad representation of race and ethnicity in the United States, we found that prenatal stress and depressive symptoms were associated with greater reports of child psychiatric symptoms. Only prenatal depressive symptoms were associated with observed decrements in cognitive abilities, most significantly in biological male children. Stress during low-risk pregnancies may be less detrimental than theorized. There was no mediation by FGV. These findings support the need to attend to even small changes in prenatal distress, as these may have long-lasting implications.

Infant temperament is associated with maternal feeding behaviors in early infancy.

Parental feeding practices shape infant eating behaviors and may impact obesity risk. For example, feeding on a schedule and using food to soothe have been associated with greater infant weight gain and future obesity risk. Most studies focus on parental determinants of feeding practices, but infant temperament might influence feeding practices parents select. Studies examining associations of infant temperament with parental feeding practices in early infancy are needed. Thus, the purpose of this cross-sectional, observational study was to test the hypothesis that infant temperament would be associated with use of food to soothe and feeding on a schedule. Mother-infant dyads (N = 98) from 3 parent birth cohort studies presented for clinic visits at infant age of 3-5 months. Mothers completed a demographic questionnaire. Feeding practices (use of food to soothe and feeding on a schedule) and maternal perceptions of 3 dimensions of infant temperament (surgency, orienting/regulating, and negative affect) were collected by survey. Spearman partial correlations were used to examine if any of the 3 infant temperament dimensions were associated with use of food to soothe or feeding on a schedule, adjusting for maternal marital status, race/ethnicity, BMI, infant age at the visit, and infant weight-for-length z-score. Greater perceived infant surgency/extraversion was associated with greater use of food to calm (Spearman partial r = 0.25, p < 0.05), but not feeding on a schedule (Spearman partial r = -0.11, p = 0.31). Greater perceived infant negative affect was associated with greater use of food to calm (Spearman partial r = 0.21, p < 0.05). Perceived infant orienting/regulating was not associated with either of the feeding practices examined. These results provide evidence that as early as 3-5 months of age, perceived infant temperament is associated with maternal feeding practices which influence infant growth outcomes.

Changes in Ghrelin and Glucagon following a Low Glycemic Load Diet in Women with PCOS.

CONTEXT: Altered satiety hormones in women with polycystic ovarian syndrome (PCOS) may contribute to obesity. Diets with a low glycemic load (GL) may influence appetite-regulating hormones including glucagon and ghrelin. OBJECTIVE: To test the hypothesis that following a 4-week, eucaloric low vs high GL diet habituation, a low vs high GL meal will increase glucagon and decrease ghrelin to reflect greater satiety and improve self-reported fullness. METHODS: Secondary analysis of a randomized crossover trial. PARTICIPANTS: Thirty women diagnosed with PCOS. INTERVENTION: Participants were provided low (41:19:40% energy from carbohydrate:protein:fat) and high (55:18:27) GL diets for 8 weeks each. At each diet midpoint, a solid meal test was administered to examine postprandial ghrelin, glucagon, glucose, insulin, and self-reported appetite scores. RESULTS: After 4 weeks, fasting glucagon was greater with the low vs high GL diet (P = .035), and higher fasting glucagon was associated with lesser feelings of hunger (P = .009). Significant diet effects indicate 4-hour glucagon was higher (P < .001) and ghrelin was lower (P = .009) after the low vs high GL meal. A trending time × diet interaction (P = .077) indicates feelings of fullness were greater in the early postprandial phase after the high GL meal, but no differences were observed the late postprandial phase. CONCLUSION: These findings suggest after low GL diet habituation, a low GL meal reduces ghrelin and increases glucagon in women with PCOS. Further research is needed to determine the influence of diet composition on ad libitum intake in women with PCOS.

Secondary analysis of gut hormone data from children with and without in utero exposure to gestational diabetes: Differences in the associations among ghrelin, GLP-1, and insulin secretion.

BACKGROUND: Intrauterine exposure to gestational diabetes mellitus (GDM) increases risk for type 2 diabetes (T2D). Ghrelin and GLP-1 have opposite functions in nutritional homeostasis and are associated with insulin secretion, but it is not known if individuals exposed to GDM exhibit dysregulation in these associations. OBJECTIVE: Test the hypothesis that children exposed to GDM in utero will exhibit dysregulation among ghrelin, GLP-1, and C-peptide (reflecting insulin secretion). METHODS: Data from N = 43 children aged 5 to 10 years were included in this secondary analysis of ghrelin, GLP-1, and C-peptide response to a liquid meal test. Repeated measures mixed model analyses were used to measure associations among hormones. RESULTS: The association of ghrelin and GLP-1 was moderated by GDM group (P < .01), such that ghrelin was inversely associated with GLP-1 in children without GDM exposure, but not for those exposed to GDM. GLP-1 was positively associated with C-peptide in both groups, but the association was stronger in those exposed to GDM (estimate = 1.06 vs 1.01). CONCLUSIONS: Differences in the associations among ghrelin, GLP-1, and C-peptide displayed here suggest novel lines of research about whether the regulation of gut hormones and insulin secretion contribute to obesity and risk for T2D in children exposed to GDM.

Associations Among Maternal Adiposity, Insulin, and Adipokines in Circulation and Human Milk.

BACKGROUND: Insulin, leptin, and adiponectin regulate energy balance and may influence infant growth via their presence in human milk. Maternal body mass index has been associated with human milk insulin, leptin, and adiponectin concentrations, but results are inconsistent. Maternal serum hormone concentrations and fat mass may better characterize human phenotype and be more appropriate predictors of human milk insulin, leptin, and adiponectin. RESEARCH AIM: To examine the associations of human milk insulin, leptin, and adiponectin with their concentrations in maternal circulation and with maternal fat mass. METHODS: Insulin, leptin, and adiponectin were measured in serum and human milk at 1 month postpartum in 25 women. Total body fat mass and fat-free mass were measured using bioelectrical impedance analysis. Linear regression modeling was used to examine associations of serum hormone concentrations or fat mass with human milk insulin, leptin, and adiponectin after adjusting for covariates. RESULTS: Serum insulin (p = .007), leptin (p < .001), and adiponectin (p < .001) were each associated with their respective concentrations in human milk. Fat mass was positively associated with insulin (p = .005) and leptin (p < .001), but not with adiponectin (p = .65), in human milk. CONCLUSIONS: Human milk insulin, leptin, and adiponectin were positively associated with their concentrations in serum, and human milk insulin and leptin were associated with maternal fat mass. Future research is needed to elucidate the role of human milk hormones in infant energy balance and growth.

Ratings of Perceived Exertion During Walking Predicts Endurance Independent of Physiological Effort in Older Women.

Hunter, GR, Neumeier, WH, Chandler-Laney, PC, Carter, SJ, Borges, JH, Hornbuckle, LM, Plaisance, EP, and Fisher, G. Ratings of perceived exertion during walking predicts endurance independent of physiological effort in older women. J Strength Cond Res 34(5): 1340-1344, 2020-This study aimed to determine whether ratings of perceived exertion (RPE) and physiological effort at different exercise intensities relate to exercise endurance. Ninety-eight sedentary women (older than 60 years) completed 3 submaximal locomotion tasks: (a) stair climbing, (b) flat walking at 2 mph, and (c) grade walking at 2 mph. Maximal treadmill endurance was measured at least 3 days before the submaximal tests. Oxygen uptake was measured during all tests, and RPE were collected for the submaximal tasks. Ratings of perceived exertion during moderate-intensity exercise (walking on the flat at 43% V[Combining Dot Above]O2max, partial R = -0.35, p < 0.01), but not higher intensity exercise (grade walk at 59% V[Combining Dot Above]O2max, p = 0.49, and stair climbing at 67% V[Combining Dot Above]O2max, p = 0.17), were related to endurance even after adjusting for aerobic capacity and physiological effort (composite of maximal heart rate, ventilation, and respiratory exchange ratio). However, physiological effort was significantly related to endurance for the higher intensity exercise (both grade walk and stair climbing partial R >-0.24, p < 0.02). Similar to previous findings that subjective ratings of fatigue at rest were related to RPE during low/moderate-intensity exercise, but not higher intensity exercise, these data further support Ekkekakis's dual-mode hypothesis that cognitive factors influence RPE during low/moderate-intensity exercise. A practical application is that the coach and personal trainer should know that physiological effort seems to play a greater role in influencing endurance than RPE as intensity of exercise increases.

Parental Self-Efficacy in New Mothers Predicts Infant Growth Trajectories.

The purpose of this study was to examine whether parental self-efficacy (PSE) is associated with change in infant weight-for-length z score (WLZ) from age 3 to 12 months. Data were drawn from the Infant Care, Feeding, and Risk of Obesity study, conducted with low-income, African American mother-infant dyads (n = 127). PSE was measured at infant age of 3 months. Infant anthropometrics were measured at infant age of 3 and 12 months, WLZ change between these time points was calculated, and infants stratified into WLZ change categories (expected, excessive, or slow). To analyze the data, ANCOVA, multiple regression, and post hoc techniques were used. Controlling for infant birthweight, PSE at 3 months was associated with infant WLZ change (η2 = 0.05, p = .04). Mothers of infants who exhibited excessive growth had higher PSE than mothers of infants who exhibited slow growth (Tukey-adjusted p = .03). This finding suggests that infants of mothers with high PSE may have increased obesity risk, but more research is needed.

Modified eating in the absence of hunger test is associated with appetitive traits in infants.

BACKGROUND: Appetite traits and feeding practices have been linked to children's weight status. For example, eating in response to food cues (high food responsiveness (FR)), and poor regulation of intake (low satiety responsiveness (SR)), increase risk for obesity. Appetitive traits of infants, and feeding practices, are typically measured by parent-report. The purpose of this study was to use a modified eating in the absence of hunger (EAH) paradigm, measuring infants' intake 30 min after a typical meal, to test whether infant acceptance of a second meal is associated with parent-reported appetitive traits or feeding practices. METHODS: Healthy infants aged 3-5 months (N = 54) were fed a typical meal and then offered a second meal by bottle 30 min later. Appetitive traits and feeding practices were assessed with surveys. Analyses of covariance were used to assess whether appetitive traits differed by acceptance of the second meal after adjusting for covariates. RESULTS: Fifty-nine percent of infants accepted the second meal and these infants had greater parent-reported FR (M = 3.06 ±â€¯0.58 vs M = 2.43 ±â€¯0.80, p < 0.01) and lower SR (M = 1.87 ±â€¯0.62 vs M = 2.67 ±â€¯0.87, p = 0.01), compared to infants who rejected it. Group differences remained after adjusting for infant age, feeding mode, weight-for-length, and maternal body mass index. No other appetitive traits or feeding practices differed by group. CONCLUSIONS: Results expand research in older children by showing that infant response to a modified EAH protocol is associated with parent-reported FR and SR. Future research with this protocol in infants should investigate the consistency of this behavior across time and examine whether response to this protocol predicts subsequent growth.

Do Women Know Their Prepregnancy Weight?

OBJECTIVE: Prepregnancy weight may not always be known to women. A model was developed to estimate prepregnancy weight from measured pregnancy weight. METHODS: The model was developed and validated using participants from two studies (Project Viva, n = 301, model development; and Fit for Delivery [FFD], n = 401, model validation). Data from the third study (Programming Research in Obesity, Growth, Environment and Social Stressors [PROGRESS]), which included women from Mexico City, were used to demonstrate the utility of the newly developed model to objectively quantify prepregnancy weight. RESULTS: The model developed from the Project Viva study validated well with low bias (R2 = 0.95; y = 1.02x - 0.69; bias = 0.68 kg; 95% CI: -4.86 to 6.21). Predictions in women from FFD demonstrated good agreement (R2 = 0.96; y = 0.96x + 4.35; bias = 1.60 kg; 95% CI: -4.40 to 7.54; error range = -11.25 kg to 14.73 kg). High deviations from model predictions were observed in the Programming Research in PROGRESS (R2 = 0.81; y = 0.89x + 9.61; bias = 2.83 kg; 95% CI: -7.70 to 12.31; error range = -39.17 kg to 25.73 kg). The model was programmed into software (https://www.pbrc.edu/research-and-faculty/calculators/prepregnancy/). CONCLUSIONS: The developed model provides an alternative to determine prepregnancy weight in populations receiving routine health care that may not have accurate knowledge of prepregnancy weight. The software can identify misreporting and classification into incorrect gestational weight gain categories.

Self-efficacy, infant feeding practices, and infant weight gain: An integrative review.

It has been suggested that self-efficacy specific to parenting or feeding may influence the decisions parents make regarding infant feeding; however, a review of this topic has not been conducted. The purpose of this integrative review is to synthesize the literature regarding the potential role of self-efficacy in infant feeding practices or infant weight gain. A total of 40 articles were used to guide this review, which were classified into three categories examining an association with self-efficacy (1) breastfeeding; (2) infant feeding practices such as parental feeding style and dietary quality; and (3) infant weight gain. Evidence regarding breastfeeding self-efficacy (BFSE) and breastfeeding is extensive; mothers with a higher sense of BFSE more often initiate breastfeeding and breastfeed for longer durations. The evidence regarding self-efficacy and the association with infant feeding practices other than breastfeeding is sparse. However, several studies report that mothers who have a higher sense of self-efficacy are more likely to follow infant feeding practices which align with recommendations. The authors have speculated an association between self-efficacy and infant weight gain; yet, to date, no study has found a significant association. More research is needed on the topic, particularly in diverse populations and with fathers and mothers.

Reasons for Late-Night Eating and Willingness to Change:A Qualitative Study in Pregnant Black Women.

OBJECTIVE: Late-night eating during pregnancy is associated with greater risk for gestational diabetes. The purposes of this study were to describe reasons why women engage in late-night eating and to understand perceptions about changing this behavior. DESIGN: Focus groups using a semi-structured interview script. SETTING: Urban university-affiliated obstetric clinic. PARTICIPANTS: Low-income black women (n = 18) with overweight/obesity at entry to prenatal care. PHENOMENON OF INTEREST: Late-night eating. ANALYSIS: Exhaustive approach coding responses to specific questions. RESULTS: Individual and interpersonal contributors to late-night eating included hunger, altered sleep patterns, fetal movement, and the influence of others. Food choices were largely driven by taste and convenience. Some women reported that they could alter nightly eating patterns, whereas others would consider changing only if late-night eating were associated with a severe illness or disability for the child. CONCLUSIONS AND IMPLICATIONS: There was considerable heterogeneity among the participants of this study regarding reasons for late-night eating during pregnancy and attitudes toward changing this behavior. Although the themes identified from this study cannot be generalized, they may be useful to inform future studies. Future research might develop strategies to overcome individual and social factors that contribute to late-night eating during pregnancy.

Relatively Low ß-Cell Responsiveness Contributes to the Association of BMI with Circulating Glucose Concentrations Measured under Free-Living Conditions among Pregnant African American Women.

BACKGROUND: Body mass index (BMI, in kg/m(2)) is positively associated with plasma glucose in late pregnancy and with risk of adverse obstetric outcomes. Much of the existing research uses single-clinic measures of plasma glucose, which may not accurately reflect circulating glucose under free-living conditions. Furthermore, little is known about circulating glucose concentrations of African American women, who tend to have poorer diet quality and a greater risk of obstetric complications. OBJECTIVE: The objective of the study was to test the hypothesis that the positive association of BMI in early pregnancy with third-trimester circulating glucose concentrations measured under free-living conditions among African American women would be at least partially attributable to lower ß-cell insulin secretion relative to insulin sensitivity [i.e., lower disposition index (DI)]. METHODS: Using a prospective, observational design, 40 pregnant African American women (mean ± SD age: 23.1 ± 4.0 y; mean ± SD BMI: 28.4 ± 7.5) wore continuous glucose monitors and accelerometers for 3 d at 32-35 wk of gestation and concurrently maintained a food diary to report their self-selected meals. The DI was derived from a 75-g oral glucose tolerance test. Linear regression modeling was used to calculate the association of BMI with the 24-h glucose (GLUC24h) and 2-h (GLUC2hPP) postprandial glucose areas under the curve and with the percentage of time the glucose concentrations were >120 mg/dL. RESULTS: The positive associations between BMI and GLUC24h (standardized ß = 0.36, P = 0.03) and the percentage of time glucose concentrations were >120 mg/dL (standardized ß = 0.40, P = 0.02) were independent of total carbohydrate intake and physical activity and were attenuated when DI was added to the model. The positive association of BMI with GLUC2hPP was attenuated when DI was added to the model, and DI itself was independently associated with GLUC2hPP after self-selected breakfast and dinner (standardized ß = -0.33 and -0.42, respectively; P = 0.01). CONCLUSIONS: The association of BMI with high circulating glucose in free-living pregnant African American women is at least partially attributable to lower ß-cell responsiveness.

Association of late-night carbohydrate intake with glucose tolerance among pregnant African American women.

Obesity and late-night food consumption are associated with impaired glucose tolerance. Late-night carbohydrate consumption may be particularly detrimental during late pregnancy because insulin sensitivity declines as pregnancy progresses. Further, women who were obese (Ob) prior to pregnancy have lower insulin sensitivity than do women of normal weight (NW). The aim of this study is to test the hypothesis that night-time carbohydrate consumption is associated with poorer glucose tolerance in late pregnancy and that this association would be exacerbated among Ob women. Forty non-diabetic African American women were recruited based upon early pregnancy body mass index (NW, <25 kg m(-2) ; Ob, ≥30 kg m(-2) ). Third trimester free-living dietary intake was assessed by food diary, and indices of glucose tolerance and insulin action were assessed during a 75-g oral glucose tolerance test. Women in the Ob group reported greater average 24-h energy intake (3055 kcal vs. 2415 kcal, P < 0.05). Across the whole cohort, night-time, but not day-time, carbohydrate intake was positively associated with glucose concentrations after the glucose load and inversely associated with early phase insulin secretion (P < 0.05). Multiple linear regression modelling within each weight group showed that the associations among late-night carbohydrate intake, glucose concentrations and insulin secretion were present only in the Ob group. This is the first study to report an association of night-time carbohydrate intake specifically on glucose tolerance and insulin action during pregnancy. If replicated, these results suggest that late-night carbohydrate intake may be a potential target for intervention to improve metabolic health of Ob women in late pregnancy.

Prospective associations of eating behaviors with weight gain in infants.

OBJECTIVE: To examine whether maternal reports of infant eating behaviors are stable over time and whether eating behaviors are prospectively associated with weight gain. METHODS: In an ongoing study of infant growth, weight and length were measured at 2 weeks, 3 months, and 5 months of age. Food responsiveness (FR), satiety responsiveness (SR), enjoyment of feeding (EF), and slow eating (SE) were assessed with the Baby Eating Behavior Questionnaire. Repeated measures ANOVA was used to examine changes in eating behaviors from 2 weeks to 5 months. Simple Pearson correlations examined associations among eating behaviors across time and associations of eating behaviors with subsequent change in weight-for-length z-scores. RESULTS: Among 31 infants studied from 2 weeks to 3 months, FR and SR remained consistent (P < 0.05), and among 21 infants studied from 3 to 5 months, FR, EF, and SE were consistent (P < 0.01). Infants ate more quickly (P < 0.01) and tended to have greater SR with age (P = 0.09). Only SE at 3 months was associated with subsequent gain in weight-for-length (P < 0.05). CONCLUSIONS: Consistent with previous research, SE was predictive of weight gain during infancy. Given that eating behaviors were largely consistent after 3 months of age, it may be important to encourage the development of healthy eating behaviors during early infancy.

Monitoring of infant feeding behavior using a jaw motion sensor.

Rapid weight gain during infancy increases the risk of obesity. Given that infant feeding may contribute to rapid weight gain, it would be useful to develop objective tools which can monitor infant feeding behavior. This paper presents an objective method for examining infant sucking count during meals. A piezoelectric jaw motion sensor and a video camera were used to monitor jaw motions of 10 infants during a meal. Videotapes and sensor signals were annotated by two independent human raters, counting the number of sucks in each 10 second epoch. Annotated data were used as a gold standard for the development of the computer algorithms. The sensor signal was de-noised and normalized prior to computing the per-epoch sucking counts. A leave-one-out cross-validation scheme resulted in a mean error rate of -9.7% and an average intra-class correlation coefficient value of 0.86 between the human raters and the algorithm.

Effects of a eucaloric reduced-carbohydrate diet on body composition and fat distribution in women with PCOS.

OBJECTIVE: To determine if consumption of a reduced-carbohydrate (CHO) diet would result in preferential loss of adipose tissue under eucaloric conditions, and whether changes in adiposity were associated with changes in postprandial insulin concentration. METHODS: In a crossover-diet intervention, 30 women with PCOS consumed a reduced-CHO diet (41:19:40% energy from CHO:protein:fat) for 8 weeks and a standard diet (55:18:27) for 8 weeks. Body composition by DXA and fat distribution by CT were assessed at baseline and following each diet phase. Insulin AUC was obtained from a solid meal test (SMT) during each diet phase. RESULTS: Participants lost 3.7% and 2.2% total fat following the reduced-CHO diet and STD diet, resp. (p<0.05 for difference between diets). The reduced-CHO diet induced a decrease in subcutaneous-abdominal, intra-abdominal, and thigh-intermuscular adipose tissue (-7.1%, -4.6%, and -11.5%, resp.), and the STD diet induced a decrease in total lean mass. Loss of fat mass following the reduced CHO diet arm was associated with lower insulin AUC (p<0.05) during the SMT. CONCLUSIONS: In women with PCOS, consumption of a diet lower in CHO resulted in preferential loss of fat mass from metabolically harmful adipose depots, whereas a diet high in CHO appeared to promote repartitioning of lean mass to fat mass.

Return of hunger following a relatively high carbohydrate breakfast is associated with earlier recorded glucose peak and nadir.

The aim of this study is to test the hypothesis that a breakfast meal with high carbohydrate/low fat results in an earlier increase in postprandial glucose and insulin, a greater decrease below baseline in postprandial glucose, and an earlier return of appetite, compared with a low carbohydrate/high fat meal. Overweight but otherwise healthy adults (n = 64) were maintained on one of two eucaloric diets: high carbohydrate/low fat (HC/LF; 55:27:18% kcals from carbohydrate:fat:protein) versus low carbohydrate/high fat (LC/HF; 43:39:18% kcals from carbohydrate:fat:protein). After 4 weeks of acclimation to the diets, participants underwent a meal test during which circulating glucose and insulin and self-reported hunger and fullness, were measured before and after consumption of breakfast from their assigned diets. The LC/HF meal resulted in a later time at the highest and lowest recorded glucose, higher glucose concentrations at 3 and 4 hours post meal, and lower insulin incremental area under the curve. Participants consuming the LC/HF meal reported lower appetite 3 and 4 hours following the meal, a response that was associated with the timing of the highest and lowest recorded glucose. Modest increases in meal carbohydrate content at the expense of fat content may facilitate weight gain over the long-term by contributing to an earlier rise and fall of postprandial glucose concentrations and an earlier return of appetite.

Arterial elasticity, strength, fatigue, and endurance in older women.

Arterial health may influence muscle function in older adults. Study purpose was to determine whether arterial elasticity is related to strength, central and peripheral fatigue, fatigue at rest, and treadmill endurance. Subjects were 91 healthy women aged >60. Treadmill endurance and maximal oxygen uptake (VO2 max) were measured. Peripheral and central fatigue for the knee extensors were evaluated using two isometric fatigue tests (one voluntary and one adding electrical stimulation). Arterial elasticity was determined using radial artery pulse wave analysis. Linear multiple regression was used in statistical analysis. Large artery elasticity was associated with central fatigue (P < 0.01) and treadmill endurance (P < 0.02) after adjusting for VO2 max and knee extension strength. Subjective fatigue at rest was related to large artery elasticity after adjusting for ethnic origin (<0.02). Strength was significantly related to small artery elasticity after adjusting for ethnic origin, leg lean tissue, age, and blood pressure. Arterial elasticity is independently related to strength and fatigue in older women, especially in the central nervous system where arterial elasticity is independently related to perceptions of fatigue at rest and central fatigue. These results suggest that arterial health may be involved with the ability of the central nervous system to activate muscle in older women.

Effects of diet macronutrient composition on body composition and fat distribution during weight maintenance and weight loss.

OBJECTIVE: Qualitative aspects of diet may affect body composition and propensity for weight gain or loss. We tested the hypothesis that consumption of a relatively low glycemic load (GL) diet would reduce total and visceral adipose tissue under both eucaloric and hypocaloric conditions. DESIGN AND METHODS: Participants were 69 healthy overweight men and women. Body composition was assessed by DXA and fat distribution by CT scan at baseline, after 8 weeks of a eucaloric diet intervention, and after 8 weeks of a hypocaloric (1000 kcal/day deficit) diet intervention. Participants were provided all food for both phases, and randomized to either a low GL diet (<45 points per 1000 kcal; n = 40) or high GL diet (>75 points per 1000 kcal, n = 29). RESULTS: After the eucaloric phase, participants who consumed the low GL diet had 11% less intra-abdominal fat (IAAT) than those who consumed the high GL diet (P < 0.05, adjusted for total fat mass and baseline IAAT). Participants lost an average of 5.8 kg during the hypocaloric phase, with no differences in the amount of weight loss with diet assignment (P = 0.39). Following weight loss, participants who consumed the low GL diet had 4.4% less total fat mass than those who consumed the high GL diet (P < 0.05, adjusted for lean mass and baseline fat mass). CONCLUSIONS: Consumption of a relatively low GL diet may affect energy partitioning, both inducing reduction in IAAT independent of weight change, and enhancing loss of fat relative to lean mass during weight loss.