Impact of Menstrual Cycle on Resting and Postprandial Metabolism in Recreationally Active, Eumenorrheic Females

Changes in estrogen and progesterone across the menstrual cycle impact many biological systems including resting and postprandial metabolism. PURPOSE: To investigate whether menstrual cycle phase impacted resting and postprandial energy expenditure (EE) and substrate utilization in recreationally active, eumenorrheic females. METHODS: In this study, 8 eumenorrheic females (mean±SD age: 33±8 years, BMI: 22.5±2.2 kg/m2; VO2max: 36.9±3.8 ml/kg/min) had resting energy expenditure (REE) and substrate utilization continuously measured with indirect calorimetry for 45 min at rest after an overnight fast, and for 3 h after a mixed meal (490 kcal, 53% carbohydrate, 31% fat, 20% protein) during three distinct phases of the menstrual cycle (early follicular, late follicular, and mid luteal). Menstrual cycle phase was determined using calendar-based counting, ovulation test strips, and confirmed via serum hormone levels (estrogen and progesterone). REE (kcal/day) was calculated using the abbreviated Weir Equation. Diet-induced thermogenesis (DIT) was calculated by subtracting REE (kcal/min) from postprandial EE (kcal/min). This value (kcal/min) was then multiplied by the testing time (180 min) to obtain DIT (kcal) for the 3-h postprandial period. A one-way, repeated measures ANOVA was used to assess differences in REE, respiratory quotient (RQ), and DIT across menstrual cycle phase. All data reported as mean±SD. RESULTS: REE was higher during mid luteal (1486±178 kcal/day) compared to early follicular (1409±108 kcal/day) and late follicular (1390±103 kcal/day) phases (F[2,14]=2.28, p=0.14; effect size=0.25). Resting RQ did not differ across menstrual cycle phase. DIT was higher during early follicular (34±8 kcal) and late follicular (32±12 kcal) than mid-luteal (23±12 kcal) phase (F[2,14]=3.02, p=0.08; effect size=0.30). Postprandial RQ was higher during early follicular (0.87±0.04) and late follicular (0.87±0.03) than mid-luteal (0.85±0.04) phase (F[2,14]=3.22, p=0.07; effect size=0.32). CONCLUSION: These preliminary results on 8 recreationally active, eumenorrheic females suggest that resting and postprandial metabolism may differ across the menstrual cycle. It is unclear whether the magnitude of these differences is clinically meaningful

Early Weaning Reduces Rangeland Herbage Disappearance

Early weaning of beef calves reduces nutrient and forage demand in a cow–calf enterprise, potentially contributing to reduction in forage utilization on the pasture from which calves are removed by a nonlactating cow vs. a cow–calf pair. Research was conducted to evaluate weaning beef calves 90 days early (EW) vs. normal weaning (NW) on pasture herbage disappearance in mixed-grass prairie pastures in the northern Great Plains. Spring-calving cows (n = 48) were utilized in each study year (2003, 2004, and 2006) from the date of early weaning (August) until the date of normal weaning (November). Cow–calf pairs were randomly assigned each year to each NW pasture (n = 8 pasture–1); cows whose calves had been weaned early were randomly assigned to each EW pasture (n = 8 pasture–1). No calves grazed EW pastures. Cattle were weighed and body condition scored at the beginning and end of each trial period. Available herbage was determined before and after grazing in each pasture. The effect of weaning treatment on cow average daily gain and body condition score change was highly significant (P \u3c 0.001). Early-weaned cows gained weight and condition; normal-weaned cows lost weight and condition. Herbage disappearance was lower (P = 0.017) in EW than NW pastures, resulting in 18.9 lb cow–1day–1, or 36%, herbage savings. This is equivalent to an additional 1.1 month of grazing saved per animal unit over a 90-day period. The value of the additional animal-unit months includes extending the grazing season, increasing cow numbers, or as “banked” forage for drought management

Evaluation of Reproduction and Blood Metabolites in Beef Heifers Fed Dried Distillers Grains Plus Solubles and Soybean Hulls During Late Gestation

Dried distillers grains plus solubles (DDGS) contain a significant amount of both undegradable intake protein and fat, which have both been shown to increase reproductive performance when supplemented to heifers during gestation. The mechanisms leading to enhanced reproduction when fat or UIP are supplemented have not been fully defined. The objective of this experiment was to evaluate DDGS or soybean hulls (SBH) fed during the last trimester of gestation on circulating concentrations of growth hormone (GH) and insulin-like growth factor-I (IGF-I) and reproductive efficiency. Ninety-five crossbred heifers were grouped by expected calving date, BW, BCS, and randomly assigned to DDGS or SBH (n = 6 pens per treatment). Diets were formulated to be isoenergetic and meet the nutrient requirements at d 240 of gestation. Diets were limit fed during the last trimester of gestation until parturition. Blood samples were collected prior to calving and once per week for 4 weeks following calving . Treatment had no effect on circulating concentrations of GH or IGF-I. Time influenced both GH and IGF-I. Circulating concentrations of GH were elevated at calving and decreased by 4 d after calving. Circulating concentrations of IGF-I rose for the first 2 d following calving and then decreased through d 6. At the start of the breeding season there was no difference between DDGS and SBH in the percent of heifers that had initiated estrous cycles (74% and 70%, respectively). There was a tendency for more DDGS treated heifers to become pregnant during a 64 d natural service breeding season compared to SBH treated heifers (92% vs 80%, respectively). There was no difference in the distribution of pregnancies throughout the breeding season between treatments. In summary, DDGS and SBH fed during the last trimester of pregnancy to heifers resulted in similar patterns of circulating concentrations of GH and IGF, but DDGS treated heifers tended to have improved pregnancy rates during a defined breeding season

Influence of Distribution of Lean Body Mass on Resting Metabolic Rate after Weight Loss and Weight Regain: Comparison of Responses is White and Black Women

Background: Little is known about the effect of weight change on regional lean body mass (LBM) distribution or on racial differences in resting metabolic rate (RMR). Objective: The study compared total and regional LBM patterns in white and black women after weight loss and regain and assessed the influence of regional LBM on variances in RMR. Design: Eighteen white and 22 black women who did not differ in age, weight, and height were studied 3 times: in the overweight state, after weight reduction to the normal-weight state, and after 1 y without intervention. Total and regional lean and fat masses were assessed by dual-energy X-ray absorptiometry. Results: White and black women did not differ significantly in mean (± SD) weight loss (13.4 ± 3.6 and 12.7 ± 3.2 kg, respectively) and regain (6.1 ± 5.5 and 6.4 ± 5.4 kg, respectively). Black subjects had significantly less trunk LBM and significantly more limb LBM at each time point (P < 0.05). In both races, weight regain was associated with significant increases in limb LBM (P < 0.05) but not in trunk LBM (P = 0.21). RMR, adjusted for total LBM and fat mass, was significantly higher in white women after weight loss (P < 0.01) and regain (P < 0.01). However, no racial difference was found when RMR was adjusted for LBM distribution. Conclusions: In both races, trunk LBM decreased with weight loss and remained lower, despite significant weight regain, which potentially reflected decreased organ mass. Regional LBM distribution explained the racial difference in RMR

Influence of distribution of lean body mass on resting metabolic rate after weight loss and weight regain: Comparison of responses in white and black women

Background: Little is known about the effect of weight change on regional lean body mass (LBM) distribution or on racial differences in resting metabolic rate (RMR). \ud \ud Objective: The study compared total and regional LBM patterns in white and black women after weight loss and regain and assessed the influence of regional LBM on variances in RMR. \ud \ud Design: Eighteen white and 22 black women who did not differ in age, weight, and height were studied 3 times: in the overweight state, after weight reduction to the normal-weight state, and after 1 y without intervention. Total and regional lean and fat masses were assessed by dual-energy X-ray absorptiometry. \ud \ud Results: White and black women did not differ significantly in mean (± SD) weight loss (13.4 ± 3.6 and 12.7 ± 3.2 kg, respectively) and regain (6.1 ± 5.5 and 6.4 ± 5.4 kg, respectively). Black subjects had significantly less trunk LBM and significantly more limb LBM at each time point (P < 0.05). In both races, weight regain was associated with significant increases in limb LBM (P < 0.05) but not in trunk LBM (P = 0.21). RMR, adjusted for total LBM and fat mass, was significantly higher in white women after weight loss (P < 0.01) and regain (P < 0.01). However, no racial difference was found when RMR was adjusted for LBM distribution. \ud \ud Conclusions: In both races, trunk LBM decreased with weight loss and remained lower, despite significant weight regain, which potentially reflected decreased organ mass. Regional LBM distribution explained the racial difference in RMR

Precision Nutrition Model Predicts Glucose Control of Overweight Females Following the Consumption of Potatoes High in Resistant Starch

Individual glycemic responses following dietary intake result from complex physiological processes, and can be influenced by physical properties of foods, such as increased resistant starch (RS) from starch retrogradation. Predictive equations are needed to provide personalized dietary recommendations to reduce chronic disease development. Therefore, a precision nutrition model predicting the postprandial glucose response (PPGR) in overweight women following the consumption of potatoes was formulated. Thirty overweight women participated in this randomized crossover trial. Participants consumed 250 g of hot (9.2 g RS) or cold (13.7 g RS) potatoes on two separate occasions. Baseline characteristics included demographics, 10-day dietary records, body composition, and the relative abundance (RA) and &alpha;-diversity of gut microbiota. Elastic net regression using 5-fold cross-validation predicted PPGR after potato intake. Most participants (70%) had a favorable PPGR to the cold potato. The model explained 32.2% of the variance in PPGR with the equation: 547.65 &times; (0 [if cold, high-RS potato], &times;1, if hot, low-RS potato]) + (BMI [kg/m2] &times; 40.66)&mdash;(insoluble fiber [g] &times; 49.35) + (Bacteroides [RA] &times; 8.69)&mdash;(Faecalibacterium [RA] &times; 73.49)&mdash;(Parabacteroides [RA] &times; 42.08) + (&alpha;-diversity &times; 110.87) + 292.52. This model improves the understanding of baseline characteristics that explain interpersonal variation in PPGR following potato intake and offers a tool to optimize dietary recommendations for a commonly consumed food

Prevalence and Social Determinants of Food Insecurity among College Students during the COVID-19 Pandemic

The coronavirus disease (COVID-19) pandemic has increased unemployment and food insecurity in the United States (US). Prior to the pandemic, college students exhibited higher rates of food insecurity than nonstudent households. The objectives of this study were to assess the prevalence and determinants of food insecurity among college students during the COVID-19 pandemic. We administered an online survey to 651 students on three diverse campuses at a state-funded university in Texas, US, in May 2020. Food security was assessed using a multistep approach that included the 2-item Food Sufficiency Screener and 6-Item USDA Food Security Survey Module (FSSM). Overall, 34.5% of respondents were classified as food insecure within the last 30 days. The strongest predictors of food insecurity were change in current living arrangement (OR = 2.70, 95% CI: 2.47, 2.95), being furloughed (OR = 3.22, 95% CI: 2.86, 3.64), laid off (OR = 4.07, 95% CI: 3.55, 4.66), or losing part-time work (OR = 5.73, 95% CI: 5.09, 6.46) due to the COVID-19 pandemic. These findings highlight the high prevalence of food insecurity among college students during the COVID-19 pandemic, with students who experienced housing insecurity and/or loss of income due to the pandemic being impacted the most