Baseline Energy Requirements Research Articles

Amoebic gill disease increases energy requirements and decreases hypoxia tolerance in Atlantic salmon (Salmo salar) smolts

Globally, Atlantic salmon (Salmo salar Linnaeus) aquaculture is now routinely affected by amoebic gill disease (AGD; Neoparamoeba perurans). The disease proliferates throughout the summer and is implicated in decreasing tolerance of salmon to environmental perturbations, yet little empirical evidence exists to support these observations. Using salmon acclimated to 15 or 19 °C, our aim was to determine the effects of clinically light-moderate (industry-relevant) AGD on metabolism (ṀO2rest and ṀO2max), aerobic scope (ṀO2max – ṀO2rest), excess post-exercise oxygen consumption (EPOC), and hypoxia tolerance. An increase in ṀO2rest (~8% and ~ 13% increase within the 15 and 19 °C acclimation groups, respectively) with increasing disease signs demonstrated an increase in baseline energy requirements as the disease progressed. Conversely, ṀO2max remained stable at both temperatures (~364 mg O2 kg−1 h−1), resulting in a decline in aerobic scope by 13 and 19% in the 15 and 19 °C groups, respectively. There was evidence of a decrease in hypoxia tolerance as the dissolved oxygen concentrations at loss of equilibrium increased by ~8% with more severe lesion coverage of the gills. These results suggest an increase in basal energy requirements and reduction in hypoxia tolerance as AGD proliferates, lending support to the idea that AGD reduces environmental tolerance. However, the lack of an effect of acclimation temperature indicates that the temperature-disease interaction may be more complicated than currently thought.

Effect of 8 weeks of supervised overfeeding on eating attitudes and behaviors, eating disorder symptoms, and body image: Results from the PROOF and EAT studies

The physiological and metabolic effects of experimental overfeeding have been extensively studied, yet only few studies have assessed overfeeding effects on eating behaviors and psychological constructs. We analyzed two 8-week overfeeding studies, the PROOF Study (N = 25; 16 males; 16 African American; 24.1 years; 25.1 kg/m2, inpatient) and the EAT Study (N = 35; 29 males; 20 White; 26.7 years; 25.5 kg/m2, free-living). In both studies, participants were overfed 40% above baseline (daily) energy requirements for eight weeks, consuming all meals under direct supervision. We assessed eating attitudes and behaviors, eating disorder symptoms, and body image via validated questionnaires and visual analog scales at baseline, week (W) 4, and W8, and at two (PROOF: W16-Post, W24-Post) and three (EAT: W12-Post, W20-Post, W32-Post) follow-up visits, respectively. Hunger, desire to eat, and food cravings (carbohydrates, total cravings) decreased during overfeeding in both studies (all Cohen's d effect sizes ≥0.3, all p ≤ .048). Depressive symptoms and fear of fatness increased in both studies (all Cohen's d ≥ 0.4, p ≤ .020), though they were still within normal limits (t-scores ~43–49). Body dissatisfaction increased in both studies during overfeeding (all Cohen's d ≥ 0.4, all p ≤ .044) and remained increased during follow-up (PROOF: W16-Post, Cohen's d = 0.9, p = .004; EAT: W12-Post and W20-Post, all Cohen's d ≥ 0.4, all p ≤ .037). Overfeeding was associated with some deleterious effects, though most returned to baseline during follow-up. However, increases in body dissatisfaction remained up to three months post-overfeeding, highlighting the need to address body image disturbance among people who experience weight gain, even if much of the gained weight is subsequently lost. Trial registrationThe PROOF Study (ClinicalTrials.gov Identifier NCT00565149); the EAT Study (ClinicalTrials.gov Identifier NCT01672632).

Mosaic metabolic ageing: Basal and standard metabolic rates age in opposite directions and independent of environmental quality, sex and life span in a passerine

AbstractCrucial to our understanding of the ageing process is identifying how traits change with age, which variables alter their ageing process and how these traits associate with fitness.Here we investigated metabolic ageing in outdoor‐living captive zebra finches experiencing foraging costs. We longitudinally monitored 407 individuals over 6 years and collected 3,213 measurements of two independent mass‐adjusted metabolic traits: basal metabolic rate (BMRm) at thermoneutral temperatures and standard metabolic rate (SMRm), measured as BMRmbut at ambient temperatures below thermoneutrality.We define mosaic or asynchronous ageing as the difference in standardized absolute ageing rates between traits, and we estimate the degree of asynchrony using the within‐individual correlation of change in trait values with age.BMRmdecreasedlinearly with age, consistent with earlier reports. In contrast, SMRmincreasedlinearly with age. The absolute standardized change with age was significantly faster for BMRmcompared to SMRm,and the within‐individual correlation of age related change was negligible. To the best of our knowledge, this is the first quantification of SMRmageing, and the finding that SMRmand BMRmage in opposite directions.Neither metabolic rate nor metabolic ageing rate were associated with variation in life span between individuals. Moreover, experimental manipulations of environmental quality that decreased BMRmand SMRmand shortened life span by 6 months (12%) did not affect the ageing of either metabolic trait. Females lived 2 months (4%) shorter than males, but none of the metabolic traits showed sex‐specific differences at any age.Our findings indicate, in contrast to the current view, that baseline energy requirements increase with age, because animals do not generally live in thermoneutral conditions, and illustrate the importance of studying the ageing phenotype in an ecologically realistic setting.A freePlain Language Summarycan be found within the Supporting Information of this article.

Metabolic adaptation is not observed after 8 weeks of overfeeding but energy expenditure variability is associated with weight recovery

A metabolic adaptation, defined as an increase in energy expenditure (EE) beyond what is expected with weight gain during overfeeding (OF), has been reported but also refuted. Much of the inconsistency stems from the difficulty in conducting large, well-controlled OF studies in humans. The primary aim of this study was to determine whether a metabolic adaptation to OF exists and if so, attenuates weight gain. Thirty-five young adults consumed 40% above their baseline energy requirements for 8 wk, and sleeping metabolic rate (SMR) and 24-h sedentary energy expenditure (24h-EE) were measured before and after OF. Subjects were asked to return for a 6-mo post-OF follow-up visit to measure body weight, body composition, and physical activity. After adjusting for gains in fat-free mass and fat mass, SMR increased by 43±123 kcal/d more than expected (P=0.05) and 24h-EE by 23±139 kcal/d (P=0.34), indicating an overall lack of metabolic adaptation during OF despite a wide variability in the response. Among the 30 subjects who returned for the 6-mo follow-up visit, those who had a lower-than-predicted SMR (basal EE) retained more of the fat gained during OF. Likewise, subjects displaying a higher-than-predicted sedentary 24h-EE lost significantly more fat during the 6-mo follow-up. Metabolic adaptation to OF was on average very small but variable between subjects, revealing "thrifty" or "spendthrift" metabolic phenotypes related to body weight loss 6 mo later. This trial was registered at clinicaltrials.gov as NCT01672632.

The effects of different caloric restriction diets on anthropometric and cardiometabolic risk factors in overweight and obese females

Background/Aim. Obesity is an established risk factor for numerous chronic diseases. The aim of this study was to investigate the effect of well-balanced different caloric restriction (CR) diets on anthropometric parameters and standard biochemical cardiovascular risk markers [lipid profile, glucose homeostasis and high sensitivity C-reactive protein (hs-CRP)] in overweight/obese females. Methods. Participants (age 20? 40 years) were randomized into 3 different CR diet groups: the group I ? restriction of 20% calories from baseline energy requirements, the group II ? restriction of 50% calories from baseline energy requirements and the group III ? alternating daily diets with 70%/30% restriction. The study lasted 42 weeks. Anthropometric parameters were measured at the start and after 4, 8, 20 and 42 weeks after dietary intervention beginning. Biochemical markers were determined at baseline and after 20 and 42 weeks from dietary restriction start. Results. Body weight, body mass index (BMI), waist circumference (WC) and body fat (in %), in the different CR diet groups significantly decreased after 42 weeks. Body weight was less 11 kg in the group I and 12 kg in the groups II and III. WC was reduced by 11 cm in the groups I and III and by 10 cm in the group II. Different CR diets had the same effects on body fat (a reduction of 15% of body fat). Total cholesterol decreased by 7% in the group I and by 8% in the group III. Low density lipoprotein (LDL) cholesterol decreased by 14% in the group I and by 13% in group III. There were no significant changes in total and LDLcholesterol levels in the group II. The atherogenic index presented as trigliceride/high density lipoprotein (TG/HDL) ratio decreased by 0.22 in the group I, by 0.25 in the group II and by 0.32 in the group III. Various CR diets had the same effects on reducing the hs-CRP levels. Conclusion. Different CR diets with the same macronutrient content are equally effective in reducing body weight, WC and body fat, improve cardiometabolic risk factors and decrease level of proinflammatory hs-CRP in overweight/obese females.

Impact of prolonged overfeeding on skeletal muscle mitochondria in healthy individuals.

Reduced mitochondrial capacity in skeletal muscle has been observed in obesity and type 2 diabetes. In humans, the aetiology of this abnormality is not well understood but the possibility that it is secondary to the stress of nutrient overload has been suggested. To test this hypothesis, we examined whether sustained overfeeding decreases skeletal muscle mitochondrial content or impairs function. Twenty-six healthy volunteers (21 men, 5 women, age 25.3±4.5years, BMI 25.5±2.4kg/m2) underwent a supervised protocol consisting of 8weeks of high-fat overfeeding (40% over baseline energy requirements). Before and after overfeeding, we measured systemic fuel oxidation by indirect calorimetry and performed skeletal muscle biopsies to measure mitochondrial gene expression, content and function in vitro. Mitochondrial function in vivo was measured by 31P NMR spectroscopy. With overfeeding, volunteers gained 7.7±1.8kg (% change 9.8±2.3). Overfeeding increased fasting NEFA, LDL-cholesterol and insulin concentrations. Indirect calorimetry showed a shift towards greater reliance on lipid oxidation. In skeletal muscle tissue, overfeeding increased ceramide content, lipid droplet content and perilipin-2 mRNA expression. Phosphorylation of AMP-activated protein kinase was decreased. Overfeeding increased mRNA expression of certain genes coding for mitochondrial proteins (CS, OGDH, CPT1B, UCP3, ANT1). Despite the stress of nutrient overload, mitochondrial content and mitochondrial respiration in muscle did not change after overfeeding. Similarly, overfeeding had no effect on either the emission of reactive oxygen species or on mitochondrial function in vivo. Skeletal muscle mitochondria are significantly resilient to nutrient overload. The lower skeletal muscle mitochondrial oxidative capacity in human obesity is likely to be caused by reasons other than nutrient overload per se. ClinicalTrials.gov NCT01672632.

Effect of 6-month caloric restriction on Cu bound to ceruloplasmin in adult overweight subjects

In a randomized clinical trial of calorie restriction (CR), we demonstrated that important cardiovascular disease (CVD) biomarkers were favorably influenced by CR alone and in conjunction with physical exercise. The aim of this study was to examine the effects of CR with or without exercise on copper bound to ceruloplasmin (CuCp), a well-known biomarker for CVD, in overweight men and women enrolled in the CALERIE phase 1 study. Forty-six individuals were randomized to one of four groups for 6 months: control, healthy weight maintenance; CR, 25% CR from baseline energy requirements; CR+exercise, 12.5% CR and 12.5% through aerobic exercise; and low-calorie diet, low-calorie diet until 15% reduction in body weight followed by weight maintenance diet. CuCp was determined in fasting blood samples by a high-performance liquid chromatography–inductively coupled plasma mass spectrometry methodology and compared with changes in body composition and markers of CVD.After 6 months, CR combined with exercise induced a decrease in plasma concentration of CuCp. CuCp was inversely correlated with insulin sensitivity at baseline and after 6 months of intervention. A cluster analysis showed that the percent change of weight after 6 months of intervention was the most important variable that could discriminate the intervention groups. The percent change of CuCp was the only other variable selected by the analysis.Decreased CuCp in overweight subjects by CR combined with exercise suggests a positive effect of this intervention on metabolic health. Further studies to explain the relationship between weight loss and CuCp and its relevance for cardiovascular health are needed.

An objective estimate of energy intake during weight gain using the intake-balance method , ,

Estimates of energy intake (EI) in humans have limited validity. The objective was to test the accuracy and precision of the intake-balance method to estimate EI during weight gain induced by overfeeding. In 2 studies of controlled overfeeding (1 inpatient study and 1 outpatient study), baseline energy requirements were determined by a doubly labeled water study and caloric titration to weight maintenance. Overfeeding was prescribed as 140% of baseline energy requirements for 56 d. Changes in weight, fat mass (FM), and fat-free mass (FFM) were used to estimate change in energy stores (ΔES). Overfeeding EI was estimated as the sum of baseline energy requirements, thermic effect of food, and ΔES. The estimated overfeeding EI was then compared with the actual EI consumed in the metabolic chamber during the last week of overfeeding. In inpatient individuals, calculated EI during overfeeding determined from ΔES in FM and FFM was (mean ± SD) 3461 ± 848 kcal/d, which was not significantly (-29 ± 273 kcal/d or 0.8%; limits of agreement: -564, 505 kcal/d; P = 0.78) different from the actual EI provided (3490 ± 729 kcal/d). Estimated EI determined from ΔES in weight closely estimated actual intake (-7 ± 193 kcal/d or 0.2%; limits of agreement: -386, 370 kcal/d; P = 0.9). In free-living individuals, estimated EI during overfeeding determined from ΔES in FM and FFM was 4123 ± 500 kcal/d and underestimated actual EI (4286 ± 488 kcal/d; -162 ± 301 kcal or 3.8%; limits of agreement: -751, 427 kcal/d; P = 0.003). Estimated EI determined from ΔES in weight also underestimated actual intake (-159 ± 270 kcal/d or 3.7%; limits of agreement: -688, 370 kcal/d; P = 0.001). The intake-balance method can be used to estimate EI during a period of weight gain as a result of 40% overfeeding in individuals who are inpatients or free-living with only a slight underestimate of actual EI by 0.2-3.8%.

Weight Gain Reveals Dramatic Increases in Skeletal Muscle Extracellular Matrix Remodeling

In animal models of obesity, chronic inflammation and dysregulated extracellular matrix remodeling in adipose tissue leads to insulin resistance. Whether similar pathophysiology occurs in humans is not clear. The aim of this study was to test whether 10% weight gain induced by overfeeding triggers inflammation and extracellular matrix remodeling (gene expression, protein, histology) in skeletal muscle and sc adipose tissue in humans. We also investigated whether such remodeling was associated with an impaired metabolic response (hyperinsulinemic-euglycemic clamp). Twenty-nine free-living males were fed 40% over their baseline energy requirements for 8 weeks. Ten percent body weight gain prompted dramatic up-regulation of a repertoire of extracellular matrix remodeling genes in muscle and to a lesser degree in adipose tissue. The amount of extracellular matrix genes in the muscle were directly associated with the amount of lean tissue deposited during overfeeding. Despite weight gain and impaired insulin sensitivity, there was no change in local adipose tissue or systemic inflammation, but there was a slight increase in skeletal muscle inflammation. We propose that skeletal muscle extracellular matrix remodeling is another feature of the pathogenic milieu associated with energy excess and obesity, which, if disrupted, may contribute to the development of metabolic dysfunction.

Calorie restriction in overweight males ameliorates obesity-related metabolic alterations and cellular adaptations through anti-aging effects, possibly including AMPK and SIRT1 activation

BackgroundCalorie restriction (CR) is accepted as an experimental anti-aging paradigm. Several important signal transduction pathways including AMPK and SIRT1 are implicated in the regulation of physiological processes of CR. However, the mechanisms responsible for adaptations remain unclear in humans. Scope of reviewFour overweight male participants were enrolled and treated with 25% CR of their baseline energy requirements for 7weeks. Characteristics, including body weight (BW), body mass index (BMI), %fat, visceral fat area (VFA), mean blood pressure (MBP) and VO2 max, as well as metabolic parameters, such as insulin, lipid profiles and inflammatory makers and the expression of phosphorylated AMPK and SIRT1 in peripheral blood mononuclear cells (PBMNCs), were determined at baseline and then after 7weeks. In addition, we assessed the effects of the serum collected from the participants on AMPK and SIRT1 activation and mitochondrial biogenesis in cultured human skeletal muscle cells. Major conclusionsAfter CR, BW, BMI, %fat, VFA and MBP all significantly decreased, while VO2 max increased, compared to those at baseline. The levels of fasting insulin, free fatty acid, and inflammatory makers, such as interleukin-6 and visfatin, were significantly reduced, whereas the expression of phosphorylated AMPK and SIRT1 was significantly increased in PBMNCs collected after CR, compared to those at baseline. The skeletal muscle cells that were cultured in serum collected after CR showed an increase in AMPK and SIRT1 activity as well as mitochondrial biogenesis. General significanceCR is beneficial for obesity-related metabolic alterations and induces cellular adaptations against aging, possibly through AMPK and SIRT1 activation via circulating factors.

Decreased luteinizing hormone pulse frequency is associated with elevated 24-hour ghrelin after calorie restriction and exercise in premenopausal women

Elevated ghrelin has been shown to be associated with reduced luteinizing hormone (LH) pulsatility in Rhesus monkeys, rats, men, and recently women. We previously reported that 24-h ghrelin concentrations are elevated in women following a 3-mo exercise and diet program leading to weight loss. We investigated whether the elevations in ghrelin following an ~3-mo exercise and diet program leading to weight loss are associated with a decrease in LH pulsatility. The nonexercising control group (Control, n = 5) consumed a controlled diet that matched energy needs, whereas energy intake in the exercise group (Energy Deficit, n = 16) was reduced from baseline energy requirements and supervised exercise training occurred five times per a week. Significant decreases in body weight (-3.0 ± 0.6 kg), body fat (-2.9 ± 0.4 kg) and 24-h LH pulse frequency (-0.18 ± 0.08 pulses/h), and a significant increase in 24-h mean ghrelin were observed in only the Energy Deficit group. The pre-post change in LH pulse frequency was negatively correlated with the change in mean 24-h ghrelin (R = -0.485, P = 0.030) and the change in peak ghrelin at lunch (R = -0.518, P = 0.019). Interestingly, pre-post change in night LH pulse frequency was negatively correlated with the change in mean day ghrelin (R = -0.704, P = 0.001). Elevated total ghrelin concentrations are associated with the suppression of LH pulsatility in premenopausal women and may play a role in the suppression of reproductive function following weight loss.

Energy Return on Energy Invested for Tight Gas Wells in the Appalachian Basin, United States of America

The energy cost of drilling a natural gas well has never been publicly addressed in terms of the actual fuels and energy required to generate the physical materials consumed in construction. Part of the reason for this is that drilling practices are typically regarded as proprietary; hence the required information is difficult to obtain. We propose that conventional tight gas wells that have marginal production characteristics provide a baseline for energy return on energy invested (EROI) analyses. To develop an understanding of baseline energy requirements for natural gas extraction, we examined production from a mature shallow gas field composed of vertical wells in Pennsylvania and materials used in the drilling and completion of individual wells. The data were derived from state maintained databases and reports, personal experience as a production geologist, personal interviews with industry representatives, and literature sources. We examined only the “upstream” energy cost of providing gas and provide a minimal estimate of energy cost because of uncertainty about some inputs. Of the materials examined, steel and diesel fuel accounted for more than two-thirds of the energy cost for well construction. Average energy cost per foot for a tight gas well in Indiana County is 0.59 GJ per foot. Available production data for this natural gas play was used to calculate energy return on energy invested ratios (EROI) between 67:1 and 120:1, which depends mostly on the amount of materials consumed, drilling time, and highly variable production. Accounting for such inputs as chemicals used in well treatment, materials used to construct drill bits and drill pipe, post-gathering pipeline construction, and well completion maintenance would decrease EROI by an unknown amount. This study provides energy constraints at the single-well scale for the energy requirements for drilling in geologically simple systems. The energy and monetary costs of wells from Indiana County, Pennsylvania are useful for constructing an EROI model of United States natural gas production, which suggests a peak in the EROI of gas production, has already occurred twice in the past century.

Estrogen and progesterone exposure is reduced in response to energy deficiency in women aged 25-40 years

Alterations in circulating steroids are believed to be important mediators of the impact that diet and exercise have on breast cancer risk and changes in bone density. This study aimed to test the hypothesis that moderate exercise training combined with caloric restriction would produce significant menstrual disturbances and alterations in ovarian steroids in premenopausal women. Sedentary premenopausal women (25-40 years; body mass index: 23.6 +/- 0.6 kg/m(2)) assigned to either a light conditioning (LC, n = 9) or an exercise combined with caloric restriction group (EX + CR, n = 24) were studied for one screening, one baseline and four intervention periods equivalent to the length of subjects' menstrual cycles. Exercise consisted of supervised training sessions, i.e. two LC or four EX + CR times per week, 30-60 min at a moderate intensity. The EX + CR group was prescribed a diet representing a caloric restriction of 20-35% below baseline energy requirements, whereas the LC group remained eucaloric. Ovarian steroid exposure was determined with daily urinary estrone-1- and pregnanediol glucuronides (E1G and PdG, respectively) and mid-cycle urinary LH measures. Fitness, body composition, and serum sex hormone binding globulin (SHBG) and serum estradiol (E2) were assessed repeatedly. The intervention produced significant increases in VO(2) max and decreases in both body weight (-3.7 +/- 0.5 kg; ranged from -8.8 to +1.8 kg) and percent body fat (-4.5 +/- 0.7%; ranged from -12 to +0.3%), which were attributable primarily to changes in the EX + CR subjects (time x group; P < 0.05). Serum E2 and urinary E1G and PdG concentrations declined significantly across the intervention period (time; P < 0.05), whereas SHBG increased transiently (time; P < 0.05) in the EX + CR subjects, with no significant changes observed in the LC group. The decrease in E1G area under the curve was significantly related to the daily energy deficit (R =0.61; P = 0.003), not the amount of weight lost. There was no significant impact of the intervention on menstrual cyclicity or the incidence of menstrual disturbances in either group. A moderate aerobic exercise training program combined with modest weight loss in accordance with recommended guidelines produces significant reductions in ovarian steroid exposure without disrupting menstrual cyclicity in premenopausal women aged 25-40 years. Exposure to a daily energy deficit is a stronger predictor of the decline in estrogen exposure than decreases in body weight.

Calorie Restriction and Bone Health in Young, Overweight Individuals

Calorie restriction (CR) is promoted to increase longevity, yet this regimen could lead to bone loss and fracture and therefore affect quality of life. Forty-six individuals were randomized to 4 groups for 6 months: (1) healthy diet (control group); (2) 25% CR from baseline energy requirements (CR group); (3) 25% energy deficit by a combination of CR and increased aerobic exercise (CR + EX group); and (4) low-calorie diet (890 kcal/d; goal, 15% weight loss) followed by weight maintenance (LCD group). Bone mineral density (total body and hip by dual-energy x-ray absorptiometry) and serum bone markers (bone-specific alkaline phosphatase, osteocalcin, cross-linked C-telopeptide of type I collagen, and cross-linked N-telopeptide of type I collagen) were measured at baseline and after 6 months. Mean +/- SE body weight was reduced by -1.0% +/- 1.1% (control), -10.4% +/- 0.9% (CR), -10.0% +/- 0.8% (CR + EX), and -13.9% +/- 0.7% (LCD). Compared with the control group, none of the groups showed any change in bone mineral density for total body or hip. Bone resorption by serum cross-linked C-telopeptide of type I collagen was increased in all 3 intervention groups, with the largest change observed in the LCD group (CR, 23% +/- 10%; CR + EX, 22% +/- 9%; and LCD, 74% +/- 16% vs control, 4% +/- 10%). Serum levels of cross-linked N-telopeptide of type I collagen were also increased in the LCD group. With regard to bone formation, bone alkaline phosphatase levels were decreased in the CR group (-23% +/- 10%) but were unchanged in the CR + EX, LCD, and control groups. Moderate CR, with or without exercise, that preserves calcium intake for 6 months leads to large changes in body composition without significant bone loss in young adults. Longer studies with assessments of bone architecture are needed to confirm that CR nutrient-dense diets have no deleterious effect on bone health. clinicaltrials.gov Identifier: NCT00099151.

PPARγ activity in subcutaneous abdominal fat tissue and fat mass gain during short-term overfeeding

As the peroxisome proliferator-activated receptor gamma (PPARgamma) plays a central role in fat mass regulation, we investigated whether initial subcutaneous PPARgamma activity is related to fat mass generation during overfeeding. Fourteen healthy female subjects (age 25 +/- 4 years, BMI 22.1 +/- 2.3 kg/m2). Subjects were overfed with a diet supplying 50% more energy than baseline energy requirements for 14 days. Fasting blood samples were analyzed for leptin, insulin and glucose. Fasting subcutaneous abdominal fat biopsies were obtained for analysis of PPARgamma1, PPARgamma2, aP2 and UCP2 mRNAs. Initial PPARgamma1 and 2, aP2 and UCP2 mRNAs were not related to fat gain (P > 0.12). However, PPARgamma1, PPARgamma2 and aP2 mRNA changes were positively related to changes in plasma leptin (P < 0.05) and, except aP2 (P = 0.06), to fat gain (P < 0.05). PPARgamma and aP2 mRNA changes were positively related (P<0.01), indicating that PPARgamma mRNA levels reflected PPARgamma activity. These data suggest that the ability to increase PPARgamma activity might be involved in the susceptibility to gain weight during a positive energy balance.

Metabolic efficiency and energy expenditure during short-term overfeeding

Objective To investigate whether efficiency of weight gain during a short period of overfeeding is related to adaptive differences in basal metabolic rate (BMR) and physical activity. Subjects Fourteen healthy females (age 25 ± 4 years, BMI 22.1 ± 2.3 kg/m 2). Design and measurements Subjects were overfed with a diet supplying 50% more energy than baseline energy requirements for 14 days. Overfeeding diets provided 7% of energy from protein, 40% from fat and 53% from carbohydrates. Body composition was determined using hydrodensitometry and isotope dilution, total energy expenditure (TEE) with doubly labeled water and basal metabolic rate (BMR) with indirect calorimetry. Physical activity (PA) was recorded with a tri-axial accelerometer. Results Body weight increased by 1.45 ± 0.86 kg (mean ± S.D.) ( P < 0.0001), fat mass increased by 1.05 ± 0.75 kg. Energy storage was 57.0 ± 17.9 MJ, which is the difference between energy intake (207.2 MJ) and energy expenditure (150.2 MJ) during overfeeding. There was no difference between metabolically efficient and metabolically inefficient subjects in changes in BMR and PA. Conclusion These results indicate that the metabolic efficiency of weight gain was not related to adaptive changes in energy expenditure.

Metabolic ecology of cockatoos in the south-west of Western Australia

This study examined the metabolic ecology of six cockatoo taxa endemic to the south-west of Western Australia. As the availability of food is one factor that may influence the abundance and distribution of these cockatoos, we document here their baseline energy requirements and feeding patterns. Evaporative waterloss was also measured as this may correlate with the aridity of the species’ environment. Basal metabolic rate was significantly lower at 0.62 ± 0.13 mL O2 g–1 h–1 for the inland red-tailed black cockatoo than 1.11 ± 0.16 mL O2 g–1 h–1 for the forest red-tailed black cockatoo, but there was no significant difference in metabolic rate between the two white-tailed black cockatoos (0.86 ± 0.18 for Carnaby’s and 0.81 ± 0.11 mL O2 g–1 h–1 for Baudin’s) or the two corellas (0.95 ± 0.12 for Butler’s and 0.70 ± 0.04 mL O2 g–1 h–1 for Muir’s). There were no significant differences between the two white-tailed black cockatoos, and between the two corellas, with respect to evaporative water loss. The inland red-tailed black cockatoo had a significantly lower rate of evaporative water loss (0.44 ± 0.07 mg g–1 h–1) than the forest red-tailed black cockatoo (0.70 ± 0.06 mg g–1 h–1), which is presumably an adaptation to its more arid habitat. The total energy content of assorted native and introduced food items that form significant proportions of the diets for these cockatoos varied from only 0.17 kJ for a 9-mg Emex australis seed to 63.9 kJ for a 3-g Banksia attenuata nut. The energy content of each food item and the estimated daily energy requirements of the cockatoos enabled the calculation of the numbers of nuts/cones/seeds required by each species for a day, which ranged from 11 B. attenuata nuts for a Carnaby’s cockatoo to 3592 Persoonia longifolia seeds for a forest red-tailed black cockatoo.

Nutritional Support During Liver Failure

Critically ill patients in varying degrees of liver failure are catabolic and consequently require expeditious caloric support. Unique problems in this group of patients essentially revolve around the diagnosis and management of hepatic encephalopathy. From the overview provided in this text, it can be concluded that, only in overt hepatic coma, should all nitrogen products be withheld while precipitating causes are evaluated. Protein should be reintroduced as rapidly as possible to avoid the consequences of protein deprivation. Once the acute intercurrent illness has resolved, the cirrhotic patient returns to baseline energy and protein requirements indistinguishable from the population at large.

Metabolic Rate of Bobcats as Influenced by Seasonal Temperatures

We used indirect respiration calorimetry to measure metabolic rate and delineate the lower critical temperature (T,,) of bobcats (Felis rufus) during summer, fall, winter, and spring. The yearly mean standard metabolic rate (SMR) within the thermoneutral zone was 79 kcal/kg body weight (BW)o75/day (range = 69-88 kcal/kg BW075/day). No difference (P < 0.05) was found between winter and summer SMR's. We measured T,, of 22.5, 7.7, -2.2, and 5.0 C for summer, fall, winter, and spring, respectively, which were similar to mean seasonal temperatures in New Hampshire. Bobcat metabolic rate increased linearly below TLC. Metabolic measurements and regional temperature information indicate that northern bobcats are commonly exposed to energy-costly temperatures during winter. This high thermoregulatory cost likely results in behavioral adaptations; e.g., microhabitat selection and sunning. J. WILDL. MANAGE. 53(1):202-205 Energetic information for northeastern bobcats includes food habits (Pollack 1951, Westfall 1956, Litvaitis et al. 1984) and digestibility of several prey species (Golley et al. 1965, Powers 1984); however, bobcat metabolic rate has only been measured during the winter (Gustafson 1984). Our understanding of bobcat energetics is limited beyond the scope of these studies. A knowledge of baseline energy requirements of bobcats, when coupled with food consumption and food assimilation information, allows the calculation of minimum prey budgets of freeranging bobcats. Impacts of climate, changing land-use patterns, and forestry practices on bobcats and their resources can likewise be evaluated through a better understanding of bobcat energetics. The purpose of our study was to determine seasonal metabolic rates and thermoneutral zones of bobcats acclimated to natural ambient temperature and photoperiod. We acknowledge the help of numerous students and the constructive reviews of E. N. Francq and J. A. Litvaitis. This project was supported with Pittman-Robertson funds (PR W-81This content downloaded from 157.55.39.102 on Thu, 23 Jun 2016 07:08:29 UTC All use subject to http://about.jstor.org/terms J. Wildl. Manage. 53(1):1989 BOBCAT METABOLISM * Mautz and Pekins 203 R-1) through the New Hampshire Fish and Game Department and McIntire-Stennis funds. This is Scientific Contribution 1538 from the New Hampshire Agricultural Experiment Sta-

Equitable performance comparison and economic evaluation of active and passive solar energy systems

An evaluation of active and passive solar energy systems is made which assigns to both systems an equal energy demand. Active systems with baseline energy requirements equivalent to those of passive systems are identified by making a careful accounting of what passive solar energy properly belongs in the building load. This analysis allows an equitable economic comparison between the two alternative design solutions to the problem of maximizing life cycle savings for a system which supplies heat to a structure with specified floor area and heating load per unit floor area.