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PubMed2000

Determinants of energy intake and energy expenditure in HIV and AIDS.

To determine the relative importance of various factors in the causation of wasting related to human immunodeficiency virus (HIV), quantitative analysis and linear structural modeling was performed on energy metabolism data collected longitudinally and prospectively from 33 men positive for the human immunodeficiency virus at 105 time points over a 3-y period before the era of highly active antiretroviral therapy. Measured variables included energy intake, total energy expenditure, resting energy expenditure, rate of change in weight, CD4 count, clinical status, appetite, and mood. Derived variables included energy balance, activity-related energy expenditure, and physical activity level. Relative contributions were assessed by linear structural modeling based on multiple regression expressing results as path coefficients for individual relationships. The primary determinant of energy balance was energy intake (r = 0.80). Total energy expenditure made a very minor contribution to energy balance (r = -0.04). Total energy expenditure was primarily determined by activity level (r = 0.91), which itself was negatively related to the presence of opportunistic infection and CD4 count. Energy intake was related to activity level (r = 0.28) and appetite (r = 0.30), which were closely interrelated (r = 0.59). Such linear structural models allow quantitative importance to be apportioned to factors determining weight change in those infected with HIV and represent a powerful tool for future metabolic studies.

AIDS-Related Opportunistic Infections↗
PubMed1997

Energy balance and liver respiratory activity in rats fed on an energy-dense diet.

In the present study energy balance and liver respiratory activity were studied in rats fed on either a control diet or an energy-dense diet. Liver respiration was assessed both without added substrates and after the addition of hexanoate, glycerol, or sorbitol. The effect of ouabain on hexanoate-supported respiration was also determined. Metabolizable energy intake and energy expenditure increased in rats fed on an energy dense diet, but body-weight gain, as well as lipid and protein content, remained unchanged. When net energy expenditure, obtained excluding the total cost of storage, was expressed as a percentage of metabolizable energy, significant differences were found between the two groups of rats. This finding supports the presence of regulatory mechanisms in rats fed on an energy-dense diet, which are useful to counteract development of obesity. In addition, a significant increase in liver respiratory activity was found in rats fed on an energy-dense diet, both in the basal state and in that stimulated by added substrates. Na/K-pump-dependent O2 consumption also increased in rats fed on an energy-dense diet. The results indicate that a greater production of metabolic heat by the liver can contribute to the increased energy expenditure found in rats fed on an energy-dense diet.

Animal Feed↗
PubMed1983

The effects of high and low energy density diets on satiety, energy intake, and eating time of obese and nonobese subjects.

The concept of time-energy displacement is based on the hypothesis that unrefined complex carbohydrates of low energy density will prolong eating time and induce satiety at a low energy intake. The present study compared the effects of diets low in energy density and high in energy density on satiety, energy intake, and eating time among 20 obese and nonobese subjects. Each diet was served over a 5-day period, and subjects were allowed to eat to satiety. With equal acceptance ratings of the diets, satiety was reached on the diet low in energy density at a mean daily energy intake one-half that of the diet high in energy density (1570 versus 3000 kcal). Eating time was significantly longer on the diet low in energy density by an average of 33%/day. Obese and nonobese subjects were comparable in their satiety ratings, energy consumption, eating time, and food acceptance. These data support the concept of time-energy displacement, which should therefore have applicability to the treatment and prevention of obesity.

Adult↗
PubMed1986

Response of body protein and energy gain in growing chicks to differences in energy intake and composition of diet.

Responses of metabolized energy, body protein gain and body energy gain of growing chicks to planes of energy intake and dietary composition of energy-yielding nutrients were studied. Ten diets were formulated to cover the entire range of composition (0-100%) of protein, fat and carbohydrate on the basis of gross energy (GE) and three sets of 10 groups of chicks were force-fed these diets at planes of 1380, 1076 and 773 kcal GE/chick per 10 d. The response surfaces of metabolized energy at each plane of GE intake were convex, and the upper two surfaces contacted in the field of 0% GE of dietary protein (PGE). The response surface of body energy gain was almost parallel to that of metabolized energy at each plane of GE intake, but the slopes of the body energy gain upward to the peak from the foot on the 100% PGE field were steep compared with those of the metabolized energy. On the other hand, the response surfaces of body protein gain at any plane of GE intake were also convex, and sloped down from the field of about 60% PGE to the higher PGE field and to the 0% PGE field. Regardless of the plane of GE intake, the body energy gain reached a plateau at about 25% PGE and the body protein gain at about 60% PGE. That body protein gain depends on both protein intake and plane of GE intake was clearly shown. On the basis of these results we calculated partial efficiency of metabolized energy utilization, and discussed validity of the classical definition of a "balanced ration."

Animal Feed↗
PubMed2004

Energy intake, metabolic balance and growth in preterm infants fed formulas with different nonprotein energy supplements.

OBJECTIVE: To study metabolic and energy balances, growth and composition of increased body mass in healthy preterm infants fed control formula or control formula with three different nonprotein energy supplements. PATIENTS AND METHODS: Growing preterm infants (birth weight < 1,500 g and gestational age < 31 weeks) were fed standard preterm formula (control group) or the same formula enriched with three different nonprotein energy supplements. An energy supplement of 23 kcal/kg/day was achieved by adding medium-chain triglyceride and dextrinomaltose in three different caloric ratios: 33:66 in group A, 66:33 in group B, and 85:15 in group C. Energy balance was determined by open-circuit continuous (5-6 hours) measurements of energy expenditure, with simultaneous measurement of 24-hour urinary nitrogen excretion. Metabolic balance was determined by measurements of energy intake, energy oxidation, and energy output in urine and stool. The composition of body mass accretion was determined as the accretion of fat and protein in the total weight gain. RESULTS: The fat accretion (4.9, 5.9, 6.2, and 3.8 g/kg/day in groups A, B, C and D, respectively) correlated directly with fat intake. Infants receiving standard energy intake had a fat percentage of weight gain significantly lower (28%) than that of the high-energy intake groups (31%, 40%, and 38% in groups A, B, and C, respectively). This difference corresponded to the results obtained from skinfold thickness measurements. CONCLUSIONS: Excess nonprotein energy is stored as fat regardless of its source (fat or carbohydrate). High caloric and medium-chain triglyceride intake in otherwise healthy growing preterm infants does not promote nitrogen retention.

Adipose Tissue↗
PubMed2005

Preprandial ghrelin is not affected by macronutrient intake, energy intake or energy expenditure.

BACKGROUND: Ghrelin, a peptide secreted by endocrine cells in the gastrointestinal tract, is a hormone purported to have a significant effect on food intake and energy balance in humans. The influence of factors related to energy balance on ghrelin, such as daily energy expenditure, energy intake, and macronutrient intake, have not been reported. Secondly, the effect of ghrelin on food intake has not been quantified under free-living conditions over a prolonged period of time. To investigate these effects, 12 men were provided with an ad libitum cafeteria-style diet for 16 weeks. The macronutrient composition of the diets were covertly modified with drinks containing 2.1 MJ of predominantly carbohydrate (Hi-CHO), protein (Hi-PRO), or fat (Hi-FAT). Total energy expenditure was measured for seven days on two separate occasions (doubly labeled water and physical activity logs). RESULTS: Preprandial ghrelin concentrations were not affected by macronutrient intake, energy expenditure or energy intake (all P > 0.05). In turn, daily energy intake was significantly influenced by energy expenditure, but not ghrelin. CONCLUSION: Preprandial ghrelin does not appear to be influenced by macronutrient composition, energy intake, or energy expenditure. Similarly, ghrelin does not appear to affect acute or chronic energy intake under free-living conditions.

Adult↗
PubMed1998

Effects of chronic growth hormone treatment on energy intake and resting energy metabolism in patients with human immunodeficiency virus-associated wasting--a clinical research center study.

In previous studies, treatment with recombinant human GH (rhGH) produced sustained increases in weight and lean body mass (LBM) and decreases in fat mass in patients with human immunodeficiency virus (HIV)-associated wasting. To evaluate the effects of chronic rhGH treatment on components of energy balance, we recruited separate subgroups of HIV-positive patients with an involuntary weight loss of 10% or more to undergo paired measurements of resting energy metabolism (n = 6) or food intake (n = 11) before and during the final week of a 3-month rhGH (0.1 mg/kg.day) treatment period. In the energy metabolism subset, resting energy expenditure (REE) and substrate oxidation rates were measured by indirect calorimetry during brief admissions to a metabolic ward. Patients in the energy intake subset prepared written 4-day food intake diaries. Body composition was measured in both groups by bioelectrical impedance analysis. Changes in weight (+2.2 +/- 0.9 and +2.2 +/- 0.6 kg), LBM (+3.2 +/- 0.6 and +3.8 +/- 0.5 kg), and fat (-1.0 +/- 0.5 and -1.6 +/- 0.5 kg) in the energy metabolism and energy intake subsets, respectively, did not differ between groups and were comparable to changes seen in a larger group of patients who received rhGH in a randomized, double blind, placebo-controlled multicenter study. In the energy metabolism subset, REE (+232 +/- 69 Cal/day; P = 0.020) and lipid oxidation (+3.1 +/- 1.0 Cal/kg LBM.day; P = 0.016) increased, whereas protein oxidation decreased (-1.3 +/- 1.0 Cal/kg LBM.day; P = 0.027) during rhGH therapy. These changes in REE and substrate oxidation are comparable to changes we noted previously in a study of the effects of short term rhGH treatment in patients with HIV-associated wasting. Moreover, the sustained increases in lipid oxidation are consistent with the decreases in body fat content that occur with rhGH treatment. In the energy intake subset, a trend for increased daily energy intake (+203 +/- 262 Cal; P = 0.456) is obviated when adjustments for changes in weight or LBM are made (+1.3 +/- 4.0 and -0.5 +/- 5.0 Cal/kg BW and LBM, respectively). Taken together, these results demonstrate that increases in weight and LBM that occur with chronic rhGH therapy are accompanied by sustained increases in REE and lipid oxidation and decreases in protein oxidation. These changes in body composition occur without a significant increase in energy intake and may, instead, represent a redistribution of body energy stores.

Adult↗
PubMed1977

[Energy and nutrient supply during childhood. I. Food intake and energy supply (author's transl)].

From 1965--1975 the food intake and energy supply of children aged 2--14 years in families of different social classes were studied with the precise weighing method. The individual child was surveyed on an average of 21--42 successive days. Energy intake increased from 1450 for boys aged 2--3 years to 2600 kcal/day for boys aged 12--14 years, girls of the same age had an energy intake between 1300 to 2400 kcal/day. The differences between boys and girls regarding energy intake, absolute and per kg body weight, are shown. Our results of the energy intake are representative for children of the same age groups in other highly industrialized countries. The energy intake of preschool-children was equally distributed among 4 meals per day, whereas in school-children it was distributed among 5 meals with different energy contents. 35--50% of the energy supply is of animal origin, 60--65% of vegetable origin. The contribution of different food groups to the energy supply and the differences in the intake of these food groups between pre-school-and school-children are demonstrated. For the individual child a survey period of 21--28 days is necessary to obtain its individual average energy intake with the maximum standard deviation. The significance of general averages for the energy supply of age groups regarding the individual child is discussed. The day to day variations of energy intake in children are shown. The significance of these variations for nutrition in health and disease is discussed.

Adolescent↗
PubMed1987

Variation of efficiency with free-energy dissipation in models of biological energy transduction.

For two models of biological free-energy transducers, it is investigated how free-energy dissipation and efficiency vary as (i) the demand for output free energy, (ii) the input free energy or (iii) the properties of the transducers themselves, are varied. One model is representative of near-equilibrium free-energy transducers in general, the other is a special case of far-from-equilibrium free-energy transduction, reminiscent of proton pumping by bacteriorhodopsin. It turns out that the relationship between efficiency and free-energy dissipation depends strongly on what varies. In some cases, free-energy dissipation increases as the efficiency increases. It is suggested that this is one reason why biological evolution has not resulted in high efficiencies and low rates of free-energy dissipation. For the near-equilibrium free-energy transducer, the free-energy dissipation at the static head steady state is minimal with respect to variations in the output force. For the far-from-equilibrium model (of bacteriorhodopsin), the static head does not correspond to such a minimum, if that free-energy transducer slips.

Bacteriorhodopsins↗
PubMed2003

Adult female rats defend "appropriate" energy intake after adaptation to dietary energy.

OBJECTIVE: To determine if adult female rats adapt to lower and higher dietary energy density. RESEARCH METHODS AND PROCEDURES: Study 1 compared high-fat (56%), high-energy density (HD) (21.6 kJ/g) and high-fat (56%), low-energy density (LD) (16.0 kJ/g) diets before surgery (two groups, 2 weeks, n = 16) and after surgery [ovariectomy (O) Sham (S); 2 x 2 factorial, n = 8; 6 weeks]. The second study (no surgery) compared high-fat (60.0%), high-energy (22.0 kJ/g) and low-fat (10.0%), low-energy (15.1 kJ/g) diets (n = 8). RESULTS: In study 1, food intake was similar for the first 2 weeks, but rats on the LD diet consumed less energy, gained less weight, and had lower nonfasted serum leptin (all p < 0.0001) than rats on the HD diet. After surgery, rats on the LD and HD diets had similar weight gain, but rats on the LD diet consumed more food (p < 0.0001) and less energy (p < 0.009). O rats consumed more food and gained more weight (p < 0.0001) than S rats. Results from study 2 were similar to those from study 1. DISCUSSION: The results demonstrated that O and S surgery rats and rats with no surgery adjust their food intake to defend a level of energy intake. This defense only occurred after a 2-week adaptation period. The major differences in final body weights and abdominal fat resulted from the initial 2 weeks before adaptation to energy density. Rats fed higher-energy diets seemed to "settle" at a higher level of adiposity, and rats fed lower-energy diets consumed more food to increase energy consumption.

Adaptation, Physiological↗
PubMed1991

The effects of high-energy feeding on energy balance and growth in infants with congenital heart disease and failure to thrive.

Failure to thrive (FTT) in infants with congenital heart disease (CHD) can be attributed to their low energy intakes and high resting energy expenditures. Energy intake, energy expenditure and growth were studied in infants with CHD on normal formula feeds and then on feeds supplemented with glucose polymer to see whether supplementation improved energy retention and growth. Mean gross energy intakes increased by 31.7% on high-energy feeding and mean weight gain improved from 1.3 g/kg per d on control to 5.8 g/kg per d on high-energy feeding. Resting oxygen consumption (VO2 ml/kg per min) was not significantly different on the two feeding regimens, although respiratory quotient rose on high-energy feeding reflecting the increased carbohydrate intake. Estimated energy costs of growth on high-energy feeding fell within the previously described range for normal infants. It is recommended that infants with CHD known to be associated with FTT are fed on high-energy diets from the time of diagnosis in order to optimize growth.

Energy Metabolism↗
PubMed1991

Limits of energy turnover in relation to physical performance, achievement of energy balance on a daily basis.

Limits of energy turnover in relation to physical performance were addressed in terms of upper and lower limit, changes during a training programme and how to regulate energy balance at a changing energy turnover. At the lower limit we stress the risk of energy restriction to reach a desired body size or body composition for reduced performance, early osteoporosis and weight cycling. The upper limit of energy turnover can be increased by the consumption of energy dense carbohydrate-rich foods. Training induces an increase in energy turnover which can initially be more then twice the calculated energy costs from laboratory measurements of physical activity. In the long term, training can induce a reduction in resting energy expenditure even while the active cell mass (muscle mass) of the body has increased. The regulation of energy balance on a day to day basis seems to be better at high levels of energy turnover either as a consequence of the physiological need or as a consequence of the fact that athletes performing at a high level of energy expenditure have learned to ingest as much food as possible.

Body Composition↗
PubMedDate not supplied

[Joint research on the precise determination of the energy and protein requirements of fattening pigs. 2. Energy and nitrogen metabolism of fattening hybrids in the fattening range of 30 to 120 kg].

In 3 experiments a total of 242 total metabolism experiments with ad libitum feeding (experiment 1), 75% (experiment 2) and 62% (experiment 3) of the energy level of the 1st experiment and approximately equal protein and amino acid doses in experiments 1-3 were carried out with 8 castrated male fattening hybrids each (large white X land race pig) X line 150) in the live weight range between 30 and 120 kg. On average, feed intake over the whole live weight range was 2.24; 1.79 and 1.50 kg/animal and day, the corresponding daily live weight gain was 729, 533 and 396 g. With regard to the digestibility of the energy and the nutrients and the metabolisable energy in % of the gross energy there was no relation to the development of the animals. The intake of metabolisable energy per kg live weight decreased with ad libitum feeding and with the advancing development at the end of the experiment in contrast to the beginning of the experiment to 53%, energy retention to 56%. The utilisation of metabolisable energy for body energy retention, taking account of a maintenance requirement of 450 kJ/kg live weight 0,62 on the average of the 3 experiments was 68.4 +/- 1.9, 70.3 +/- 2.0 and 64.3 +/- 2.6%. Energy retention in experiments 1 to 3 amounted to 8.6, 6.8 and 5.3 MJ at the beginning and to 18.1, 12.2 and 8.0 MJ per animal and day at the end of the experiment. Protein energy retention of the pigs (live weight 40 kg) was 26% of the total energy retention in experiments 1 and 2 and 49% in experiment 3. In experiments 1 and 3 protein retention decreased to 15% of the total energy retention, in experiment 2 protein retention remained constantly at 22% between 60 and 110 kg live weight and then decreased to 18%. Consequently, the N-balances were 23-16 g, 16-20 g and 16-9 g/animal and day. The chemical composition of the carcasses was strongly influenced by the level of nutrition. At the beginning of the experiment the protein content averaged between 49 and 57% and the total fat content between 31 and 38% of the dry matter. At the end of the experiment the carcasses of the animals from experiments 1-3 had crude protein contents of 28, 33 and 42% and total fat contents of 66, 61 and 50% of the dry matter.

Animal Feed↗
PubMed2002

The decrease in body fat in mice fed conjugated linoleic acid is due to increases in energy expenditure and energy loss in the excreta.

We carried out energy balance studies in four groups of young, growing, 5-wk-old Balb-C mice (n = 12/group) that were either food restricted or nonrestricted and fed high fat diets (38 energy%) with or without 0.93 g/100 g conjugated linoleic acid (CLA) for 39 d. The energy in carcasses, excreta and food was measured in a bomb calorimeter. CLA lowered the percentage of the energy intake that was stored in the body from 1.9 +/- 0.8 to -2.3 +/- 0.7% (mean +/- SD, P < 0.05) in the nonrestricted mice and from 1.4 +/- 1.3 to -2.9 +/- 0.7% (P < 0.05) in the restricted mice. Thus, the CLA-treated mice had a net loss of body energy. The percentage of the energy intake eliminated in the excreta increased from 7.6 +/- 0.9% in controls to 8.7 +/- 1.0% (P < 0.05) in the CLA-treated mice that were nonrestricted and from 7.3 +/- 0.8 to 8.4 +/- 0.6 (P < 0.05) in the restricted mice. The amount of energy ingested minus the amount retained in carcasses and excreta equals the energy expenditure. The percentage of the energy intake that was expended as heat increased from 90.5 +/- 1.2 in controls to 93.6 +/- 1.5% (P < 0.05) in the CLA-treated nonrestricted mice and from 91.3 +/- 1.5 to 94.5 +/- 1.0% (P < 0.05) in the restricted mice. The lower energy storage in the CLA-fed mice was accounted for by an increase in the energy expenditure (74%) and by an increase in energy lost in the excreta (26%). Feeding CLA also increased liver weight, which may warrant further studies on the safety of CLA.

Adipose Tissue↗
PubMed2005

Fold helical proteins by energy minimization in dihedral space and a DFIRE-based statistical energy function.

Statistical energy functions are discrete (or stepwise) energy functions that lack van der Waals repulsion. As a result, they are often applied directly to a given structure (native or decoy) without further energy minimization being performed to the structure. However, the full benefit (or hidden defect) of an energy function cannot be revealed without energy minimization. This paper tests a recently developed, all-atom statistical energy function by energy minimization with a fixed secondary helical structure in dihedral space. This is accomplished by combining the statistical energy function based on a distance-scaled finite ideal-gas reference (DFIRE) state with a simple repulsive interaction and an improper torsion energy function. The energy function was used to minimize 2000 random initial structures of 41 small and medium-sized helical proteins in a dihedral space with a fixed helical region. Results indicate that near-native structures for most studied proteins can be obtained by minimization alone. The average minimum root-mean-squared distance (rmsd) from the native structure for all 41 proteins is 4.1 A. The energy function (together with a simple clustering of similar structures) also makes a reasonable selection of near-native structures from minimized structures. The average rmsd value and the average rank for the best structure in the top five is 6.8 A and 2.4, respectively. The accuracy of the structures sampled and the structure selections can be improved significantly with the removal of flexible terminal regions in rmsd calculations and in minimization and with the increase in the number of minimizations. The minimized structures form an excellent decoy set for testing other energy functions because most structures are well-packed with minimum hard-core overlaps with correct hydrophobic/hydrophilic partitioning. They are available online at http://theory.med.buffalo.edu.

Algorithms↗
PubMed2006

Association of energy intake and energy balance with postmenopausal breast cancer in the prostate, lung, colorectal, and ovarian cancer screening trial.

Energy restriction remains one of the most effective ways known to prevent breast cancer in animal models. However, energy intake has not been consistently associated with risk of breast cancer in humans. In a prospective study, we assessed whether energy intake, body size, and physical activity each independently influence breast cancer risk in postmenopausal women and estimated the joint effect of combinations of these individual factors. As part of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, 38,660 women, ages 55 to 74 years and recruited from 10 centers in the United States during 1993 to 2001, were randomized to the screening arm of the trial. At baseline, the women completed a self-administered questionnaire, including a food frequency questionnaire. During follow-up from 1993 to 2003, 764 incident breast cancer cases were ascertained. Women in the highest quartile of energy intake (> or = 2,084 kcal/d) compared with those in the lowest quartile (<1,316 kcal/d) had a significantly increased risk for breast cancer [multivariate relative risk (RR), 1.25; 95% confidence interval (95% CI), 1.02-1.53; P(trend continuous) = 0.03]. Current body mass index (BMI) was also positively and significantly associated with risk (multivariate RR comparing >30 kg/m2 with <22.5 kg/m2, 1.35; 95% CI, 1.06-1.70; P(trend) = 0.01). Women with > or = 4 hours/wk of vigorous recreational physical activity had a significantly reduced risk of breast cancer compared with those who reported no recreational physical activity (multivariate RR, 0.78; 95% CI, 0.60-0.99; P(trend) = 0.15). None of these associations with individual energy balance measures was substantially confounded by the other two measures. When we estimated the joint effect of all three variables, women with the most unfavorable energy balance (the highest energy intake, highest BMI, and least physical activity) had twice the risk (RR, 2.10; 95% CI, 1.27-3.45) of women with the most favorable energy balance (the lowest energy intake, lowest BMI, and most physical activity). Although our estimates of absolute energy intake, based on a food frequency questionnaire, are imperfect, these results suggest that energy intake, in addition to BMI and physical activity may be independently associated with breast cancer risk. In addition, these three aspects of energy balance may act jointly in determining breast cancer risk.

Aged↗