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PubMed1986

An energy 'sources' and 'fractions' approach to the mechanical energy expenditure problem--II. Movement of the multi-link chain model.

Movement of a multi-link chain model is treated using the 'sources' and 'fractions' concept introduced earlier (part I of this series, J. Biomechanics 19, 287-293). 'The energy balance equations', i.e. the relations between the powers of the sources and the time rate of change of the total energy of the links are obtained. It is shown that the action of joint forces can promote energy transfers between links and energy transformations of the energy fractions of the links but it cannot change the total energy of the system. A formula for the mechanical energy expenditure for the control moments is deduced. 'External' and 'internal' energy balance equations are derived. 'External' energy is the energy of the general center of mass, 'internal' energy is the energy of the links in their motion relative to the general center of mass. It is shown that 'external' and 'internal' work depend on each other and their sum is not equal to the mechanical energy expenditure which occurs during movement of the body. This is because of the possibility of some source powers to change the external and internal energy of the system simultaneously out of phase with each other.

Biomechanical Phenomena↗
PubMed2005

Consequences of food energy excess and positive energy balance.

This paper discusses possible consequences of energy excess throughout the life cycle. Firstly we consider the effects of foods on hunger, satiety and satiation. Also, the changes in food availability and consumption in relation to changes in social and economic determinants of energy excess. The relationship between physical activity and energy intake (EI) is also considered. Secondly we explore the definition of energy excess and the metabolic effects of macronutrients (mainly in relation to fuel partitioning oxidation/storage) on energy balance. The cellular and molecular regulation determined by specific genes involved in lipogenesis, fuel partitioning and/or in energy dissipation are explored. Thirdly, we examine the main consequences induced by energy excess and positive energy balance, starting with the alterations in glucose utilisation (insulin resistance) leading to type 2 diabetes and the linkage of energy excess with other non-communicable diseases (NCDs). Biological, social and psychological consequences during perinatal, childhood and adolescence periods are specifically analysed. Fourthly, the transition from energy deficit to excess, under the optic of a developing country is analysed with country examples drawn from Latin America. The possible role of supplementary food programmes in determining positive energy balance is discussed especially in relation to pre-school and school feeding programmes. Fifthly, we deal with the economic costs of energy excess and obesity related diseases. Finally, some areas where further research is needed are described; biological and genetic determinants of individual and population energy requirements, foods and food preparations as actually consumed, consumer education and research needs on social determinants of energy imbalances.

Adolescent↗
PubMed1992

Energy and nitrogen intake, expenditure and retention at 32 degrees in growing fowl given diets with a wide range of energy and protein contents.

Heat production (HP) and the intake and retention of energy and nitrogen were measured in growing broiler fowl kept at 32 degrees and given diets with metabolizable energy contents from 8 to 15 MJ/kg and crude protein (N x 6.25; CP) contents of 130 and 210 g/kg. The temperature of 32 degrees was chosen for comparison with earlier measurements at 20 degrees to minimize heat produced for the maintenance of body temperature. The effects of diet composition were observed when the same birds were taken from 20 to 32 degrees. The tendency for energy intake to increase with dietary energy concentration was less at 32 than at 20 degrees. The lower heat increments measured for the high-fat diets did not, therefore, confer an increased ability to sustain higher energy intake at 32 degrees. HP was about 17% lower at 32 than at 20 degrees; the change in HP between 20 and 32 degrees was not significantly influenced by diet composition. The absence of significant effects of diet composition on HP, combined with the significant trend in energy intake, produced significant differences (related both to dietary energy and dietary protein concentrations) in total energy retention and in the partition of retained energy between protein and fat. As at 20 degrees, variation in energy retention and in the composition of retained energy were the main responses to variation in dietary CP concentration and energy intake; a significantly higher energy cost of unit protein accretion on the low-CP diets was insufficient to produce an elevation in total HP because the higher unit energy cost was balanced by a lower absolute rate of protein accretion.

Animal Nutritional Physiological Phenomena↗
PubMed1994

[Energy and nitrogen metabolism of pregnant and lactating sows in addition to the suckling piglets. 4. Chemical composition and energy content of the conception products, reproductive organs and the live weight gain or loss in pregnant or lactating sows].

The chemical composition and the energy content of the conception products, the reproductive organs and the live weight gains or losses of pregnant and lactating sows were determined in dependence on the litter number (1, 2 and 4) and the energy supply (120, 100 and 80% of requirement recommendation) of sows as well as on the course of gestation and lactation. The results will be used as a basis for factorial derivation of requirement recommendation. The deposition of protein and energy in the conception products in dependence on the time is characterized by an exponential function. The deposition of nutrients and energy in the conception products is increased with rising litter size. The deposition of nutrients and energy per fetus is lower in the litter number 1 than in the litter number 2 and 4. The energy supply in the selected limits has no significant influence on the litter size as well as on the intrauterine deposition of nutrients and energy. The litter number, the energy supply as well as the course of gestation and lactation influence considerably the weight, the chemical composition and the energy content in the mammary gland. The chemical composition and the energy content of the live weight gains or losses of pregnant and lactating sows are strong affected by the energy supply. The increased energy supply of the pregnant sows is connected with increased live weight gains and with increased contents of dry matter, fat and energy however decreased contents of protein in the live weight gains. The live weight losses of the lactating sows are connected with mobilisation of body fat and body protein. The proportion of body fat to body protein degradation is increased with increased losses of body weight. Regression equations are calculated for the relationships between course of gestation and lactation respectively and deposition of protein and energy in the conception products, reproductive organs and maternal live weight gains or losses of sows.

Animals↗
PubMed2001

Energy requirements of lactating women derived from doubly labeled water and milk energy output.

Instead of using an incremental approach to assess the energy requirements of lactation, a more comprehensive approach may be taken by measuring total energy expenditure (TEE), milk energy output and energy mobilization from tissue stores. The latter approach avoids assumptions regarding energetic efficiency and changes in physical activity and adiposity. The purpose of this study was threefold: to assess the energy requirements of lactation; to compare these estimates with energy requirements in the nonpregnant, nonlactating state and to test for energetic adaptations in basal metabolic rate (BMR) and physical activity during the energy-demanding process of lactation. Milk production and composition, body weight and composition, TEE, BMR and physical activity levels were measured in 24 well-nourished women during exclusive breastfeeding at 3 mo postpartum and after the cessation of breastfeeding at 18 or 24 mo postpartum. TEE was measured by the doubly labeled water method, milk production by 3-d test-weighing, milk energy by bomb calorimetry on a 24-h milk sample, body composition by dual-energy x-ray absorptiometry and BMR by room respiration calorimetry. TEE, BMR and physical activity level (physical activity level = TEE/BMR) did not differ between the lactating and nonlactating state (TEE 10.0 +/- 1.5 versus 10.6 +/- 2.1 MJ/d). Mean milk energy output was equivalent to 2.02 +/- 0.33 MJ/d. Total energy requirements were greater during lactation than afterward (12.0 +/- 1.4 versus 10.6 +/- 2.1 MJ/d, P: = 0.002). Energy mobilization from tissue stores (-0.65 +/- 0.97 MJ/d) resulted in net energy requirements during lactation of 11.4 +/- 1.8 MJ/d. Because adaptations in basal metabolism and physical activity were not evident in these well-nourished women, energy requirements during lactation were met primarily from the diet and only partially by mobilization of tissue stores.

Adult↗
PubMed2003

Limits to sustained energy intake. VII. Milk energy output in laboratory mice at thermoneutrality.

The limits to sustained energy intake at peak lactation could be imposed peripherally, by the capacity of the mammary glands, or centrally, by the capacity of the animal to dissipate body heat generated as a by-product of processing food and producing milk. To distinguish between the two hypotheses, we examined milk energy output at peak lactation in MF1 laboratory mice exposed to 30 degrees C (N=12), 21 degrees C (N=10; published data) and 8 degrees C (N=10; published data). The peripheral limitation hypothesis predicts that milk energy output will remain constant at different temperatures, while the heat dissipation limit hypothesis predicts a decline in milk energy output as temperature increases. Since estimates of milk energy output in small mammals can vary depending on the calculation method used, we evaluated the milk energy output of mice (N=24) using four different methods: (1) as the difference between metabolizable energy intake and daily energy expenditure of the female, (2) from female water turnover, (3) from pup water turnover and (4) from the energy budget of the litter. We assessed these four methods by comparing their accuracy, precision and sensitivity to changes in parameters involved in the calculations. Methods 1, 3 and 4 produced similar estimates of milk energy output, while those derived from female water turnover were significantly lower and more variable. On average, mice at 30 degrees C exported significantly less energy as milk (87.7 kJ day(-1)) than mice at 21 degrees C (166.7 kJ day(-1)) and 8 degrees C (288.0 kJ day(-1)). This reduction in milk energy output at 30 degrees C was caused by a significant decline in both milk flow (20.0 g day(-1), 12.9 g day(-1) and 8.5 g day(-1) at 8 degrees C, 21 degrees C and 30 degrees C, respectively) and gross energy content of milk (14.6 kJ g(-1), 13.1 kJ g(-1) and 10.5 kJ g(-1) at 8 degrees C, 21 degrees C and 30 degrees C, respectively). Milk produced at 30 degrees C contained significantly less total solids (34.4%) than milk at 21 degrees C (40.9%) and 8 degrees C (41.5%) and significantly less fat (20.0%) than milk at 21 degrees C (26.4%) and 8 degrees C (30.3%). The reduced milk energy output in mice exposed to 30 degrees C, paralleled by their reduced food intake and low reproductive output, argues against the peripheral limitation hypothesis and provides strong support for the heat dissipation limit hypothesis.

Animals↗
PubMed1990

Energy and nitrogen intake, expenditure and retention at 20 degrees in growing fowl given diets with a wide range of energy and protein contents.

Heat production (HP) and the intake and retention of energy and nitrogen were measured at 20 degrees in growing female broiler fowl given diets with metabolizable energy (ME) contents ranging from 8 to 15 MJ/kg at each of two crude protein (nitrogen x 6.25; CP) contents (130 and 210 g/kg). ME intake was partially controlled by the birds, but increased by 30% over the range of dietary ME concentration. CP intake varied directly with dietary CP: ME ratio, indicating that control of energy intake took priority and that food intake did not increase in order to enhance amino acid intake on low-CP diets. Maintenance energy requirement and fasting HP were not affected by diet. Although the HP of fed birds was significantly affected by dietary energy source, there was no evidence for regulatory diet-induced thermogenesis as energy intake increased. Total energy retention doubled on the higher-energy diets as a result of increased intake and retention efficiency in the absence of any compensation by diet-induced thermogenesis. The proportion of energy retained as fat was negatively correlated with dietary CP: ME ratio. It was concluded that the growing female broiler fowl responded to large differences in energy intake and dietary CP concentration not by changes in rate of energy dissipation as heat but by changes in the quantity of energy retained and in the partition of retained energy between body protein and body fat.

Animal Feed↗
PubMed1994

Energy metabolism during pregnancy: influence of maternal energy status.

Additional energy requirements for term pregnancies are traditionally estimated as 1200 kJ/d or 325 MJ. These estimates approximate measured energy costs for well-nourished women, but non-Western populations subsisting on limited diets have much lower expenditures. Based on recent studies of energy expenditure during pregnancy, this paper reviews the 1) association between gestational weight gain and fat gain, 2) the influence of maternal energy status on basal metabolic energy expenditure in late pregnancy, and 3) potential energy metabolism adaptations available to pregnant women and how adaptations vary with energy status. Available data suggest that additional energy requirements during pregnancy vary from 0 to 500 MJ and depend on maternal energy status. If energy supplies are limited, adaptations spare energy for fetal growth; if energy is abundant, energy balance may be achieved in different ways depending on individual behavioral changes in food intake or activity patterns and on adjustments in basal metabolism or fat deposition.

Adipose Tissue↗
PubMed1995

Energy balance during an 8-wk energy-restricted diet with and without exercise in obese women.

The effects of severe energy restriction alone (2.0 MJ/d for 4 wk and subsequently 3.5 MJ/d for 4 wk) or energy restriction plus moderate exercise on energy balance were studied in 20 healthy obese women. Subjects aged 25-50 y were matched on the basis of body mass index and percentage body fat and randomly assigned to diet alone (D) or diet and exercise (DE) for 8 wk. DE resulted in a significantly increased loss of fat mass compared with D (7.8 +/- 0.8 compared with 5.5 +/- 0.8 kg; P < 0.05). The average daily metabolic rate measured with doubly labeled water decreased with both treatments, with no differences between the treatments. Energy balance data show that the DE treatment resulted in a significantly greater energy deficit than the D treatment. The relative contribution of fat to energy expenditure during exercise was significantly enhanced by DE treatment whereas it did not change after D. The energy expended on physical activity was not changed at the end of both treatments, with no differences between the two groups. The unchanged energy expended on physical activity indicates that DE might be accompanied by partial compensation of daily physical activities outside the training for the energy expended during the training. The energy deficit due to energy restriction alone was not compensated by a decrease in free-living daily physical activities. Addition of moderate exercise to an energy-restriction program in obese women has advantages with respect to changes in body composition, energy expenditure, and substrate utilization.

Adult↗
PubMed2002

Validity of reported energy expenditure and energy and protein intakes in Swedish adolescent vegans and omnivores.

BACKGROUND: It is difficult to obtain accurate reports of dietary intake; therefore, reported dietary intakes must be validated. Researchers need low-cost methods of estimating energy expenditure to validate reports of energy intake in groups with different lifestyles and eating habits. OBJECTIVE: We sought to validate the reported energy expenditure and energy and protein intakes of Swedish adolescent vegans and omnivores. DESIGN: We compared 16 vegans (7 females and 9 males; mean age: 17.4 +/- 0.8 y) with 16 omnivores matched for sex, age, and height. Energy expenditure as reported in a physical activity interview and energy and protein intakes as reported by diet history were validated by using the doubly labeled water method and by measuring urinary nitrogen excretion. RESULTS: The validity of reported energy expenditure and energy and protein intakes was not significantly different between vegans and omnivores. The physical activity interview had a bias toward underestimating energy expenditure by 1.4 +/- 2.6 MJ/d (95% CI: 2.4, 0.5 MJ/d). The diet-history interview had a bias toward underestimating energy intake by 1.9 +/- 2.7 MJ/d (95% CI: 2.9, 1.0 MJ/d) but showed good agreement with the validation method for nitrogen (protein) intake (underestimate of 0.40 +/- 1.90 g N/d; 95% CI: 1.10, 0.29 g N/d). CONCLUSIONS: The physical activity and diet-history interviews underestimated energy expenditure and energy intake, respectively. Energy intake and expenditure were underestimated to the same extent, and the degree of underestimation was not significantly different between vegans and omnivores. Valid protein intakes were obtained with the diet-history method for both vegans and omnivores.

4-Aminobenzoic Acid↗
PubMed2002

[Effect of composition of enteral nutrition on energy expenditure and CO2 production during periods of average and excessive energy intake].

UNLABELLED: The objective of the presented work is to evaluate to what extent the CO2 production and O2 utilization and energy metabolism at rest (REE) are influenced by an excessive nutrient intake and to what extent by the composition of enteral nutrition. REE, CO2 production and O2 utilization were investigated in 9 patients on complete enteral nutrition by indirect calorimetry in four modifications: I--nutrition with 40% kJ fat in a ration 1.2x the energy output at rest at the onset of the trial; II--40% kJ and high energy intake (2.4x energy output at rest; III--60% kJ fat in ration of 1.2x energy output at rest; IV--60% kJ fat and energy intake 2.4x energy output at rest. At 40% (I) and 60% (III) fat content in a caloriocally adequate diet the energy output at rest, the CO2 production and O2 utilization did not differ (mean +/- SD: 1438 +/- 264.1 kcal/24 h, 179 +/- 31.6 nl/min, 209 +/- 38.1 ml/min vs. 1431 +/- 342.7, 190 +/- 54.2, 207 +/- 46.5). Comparison of modifications II and IV revealed a significant (p < 0.05) increase of CO2 production on a diet rich in carbohydrates (218 +/- 52.0 vs. 202 +/- 42.3). The energy output at rest (1674 +/- 389.6 vs. 1661 +/- 378.7), nor O2 production (240 +/- 54.5 vs. 242 +/- 55.4) changed. Overfeeding with 40% fat (II) as compared with (I) led to a rise of the energy output at rest (p < 0.05), O2 utilization (p < 0.05) and CO2 production (p < 0.01). Overfeeding with lipids (IV) led as compared with III to a rise of the energy output at rest and O2 utilization; CO2 production did not change. CONCLUSION: The composition of enteral nutrition according to the described modification does not influences the energy output at rest, O2 utilization and CO2 production under conditions of an adequate energy intake. In case of an excessive nutrient intake nutrition with 60% fat does not lead to an increase of CO2 production.

Adolescent↗
PubMed1999

Effects of dietary viscosity and energy density on total daily energy consumption by young Peruvian children.

BACKGROUND: Results of prior studies of the effect of viscosity reduction of high-energy-density, starch-containing diets on young children's energy intakes are inconsistent, possibly because of differences in the characteristics of the unmodified diets with which the low-viscosity diets were compared. OBJECTIVE: Our objective was to determine the effects of dietary viscosity and energy density on total daily energy consumption by young, non-breast-fed children. DESIGN: We measured the amount of food consumed and the duration of meals during 3 substudies, in each of which 3 study diets were offered for 4 consecutive days each in random sequence: high energy density, high viscosity (HD-HV); high energy density, low viscosity (HD-LV); and low energy density, low viscosity (LD-LV). The viscosity and energy density of the unmodified starch-containing HD-HV diet were varied across substudies to determine whether the effect of amylase liquefaction was related to the initial characteristics of the HD-HV diet. The viscosity of the HV diets ranged from 79000 to 568000 mPa s; energy density of the HD diets ranged from approximately 4.18 to 4.93 kJ (1.00-1.18 kcal)/g. Viscosity of the LV diets was approximately 3000 mPa s and the energy density of the LD diets was approximately 2.47 kJ (0.6 kcal)/g. RESULTS: In each substudy, children consumed more of the LD-LV diet (g kg body wt(-)(1) d(-)(1)) than of the other diets and more of the HD-LV diet than of the HD-HV diet (P < 0.001). Energy consumption from the HD-LV diet was greater than from the other diets (P < 0.001), but the energy intakes from the latter diets were not significantly different. CONCLUSION: Amylase liquefaction of HD-HV porridges resulted in increased energy consumption by young children.

Anthropometry↗
PubMed1999

Energy density but not fat content of foods affected energy intake in lean and obese women.

BACKGROUND: Studies have shown that energy intake increases when both the fat content and energy density of the entire diet increases. When the fat content and energy density vary independently of one another, however, energy density, but not fat content, influences intake. OBJECTIVE: The present study examined whether energy intake in lean and obese women is affected when either the energy density or the fat content of a portion of the diet is manipulated and palatability is held constant. DESIGN: In a within-subjects design, 17 lean and 17 obese women consumed meals in the laboratory for four, 4-d test periods. In 3 of these test periods the energy density (4.4 and 6.7 kJ/g) or the fat content (16% and 36% of energy) of compulsory entrees representing 50% of each subject's usual energy intake was manipulated. Additional self-selected foods were consumed ad libitum at meals and as snacks. RESULTS: There were no systematic differences in palatability of the manipulated foods across conditions. Obese and lean participants responded similarly to the dietary manipulations. Intake of self-selected foods at meals was reduced significantly by 16% for both lean and obese subjects in the low- compared with the high-energy-density condition. The fat content of the compulsory foods had no significant effect on energy intake. Ratings of hunger did not differ between diets. CONCLUSION: These results indicate that when a portion of the diet was manipulated, the energy density, but not the fat content, of the foods affected total energy intake at meals in both lean and obese women.

Adolescent↗
PubMed2003

A model for energy transfer in inelastic molecular collisions applicable at steady state or non-steady state and for an arbitrary distribution of collision energies.

A new model for energy exchange between translational and internal degrees of freedom in atom-molecule collisions has been developed. It is suitable for both steady state conditions (e.g., a large number of collisions with thermal kinetic energies) and non-steady state conditions with an arbitrary distribution of collision energies (e.g., single high-energy collisions). In particular, it does not require that the collision energies be characterized by a quasi-thermal distribution, but nevertheless it is capable of producing a Boltzmann distribution of internal energies with the correct internal temperature under quasi-thermal conditions. The energy exchange is described by a transfer probability density that depends on the initial relative kinetic energy, the internal energy of the molecule, and the amount of energy transferred. The probability density for collisions that lead to excitation is assumed to decrease exponentially with the amount of transferred energy. The probability density for de-excitation is obtained from microscopic reversibility. The model has been implemented in the ion trap simulation program ITSIM and coupled with an Rice-Rampsberger-Kassel-Marcus (RRKM) algorithm to describe the unimolecular dissociation of populations of ions. Monte Carlo simulations of collisional energy transfer are presented. The model is validated for non-steady state conditions and for steady state conditions, and the effect of the kinetic energy dependence of the collision cross-section on internal temperature is discussed. Applications of the model to the problem of chemical mass shifts in RF ion trap mass spectrometry are shown.

Journal Article↗
PubMed1996

Correlation of kinetic energy losses in high-energy collision-induced dissociation with observed peptide product ions.

In collision-induced dissociation, some of an incident parent ion's kinetic energy is converted into internal energy upon collision with a neutral target. The kinetic energy lost is related to the amount of internal energy deposited into any individual ion. To see dissociations of different critical energies on the same time scale, different amounts of internal energy need to be deposited. This should be reflected in the kinetic energy lost by the parent ion in the formation of different product ions. Variable amounts of energy loss in the formation of different peptide product ions are reported here. It is seen that different product ion types (b, y, a) show ordered patterns of energy losses. A greater energy loss is observed for the formation of b-type product ions than for y-type, and even greater energy losses are observed for the formation of a-type product ions. A very good correlation between ion type energy loss and ion mass is observed. Thus, measuring the energy losses in the formation of product ions may provide a means for classifying the product ion type.

Amino Acid Sequence↗
PubMed2003

Microwave, irrigated, pulsed, or conventional radiofrequency energy source: which energy source for which catheter ablation?

The aim of the study was to compare the diameter of endomyocardial lesions induced with the delivery of microwave, cooled, or pulsed energy versus conventional RF energy. In vitro tests were performed in fresh endomyocardial preparations of pig hearts in a 10-L bath of NaCl 0.9% solution at 37 degrees C and constant 1.5 L/min flow. Ablation 7 Fr catheters with 4-mm tip electrodes were used, except for the delivery of microwave energy. Energy delivery time was set to 60 s/50 W in all experiments. Cooled energy delivery was performed with a closed irrigation catheter. Pulsed energy delivery was performed using a special controller with a duty-cycle of 5 ms. Microwave energy was delivered with a 2.5-GHz generator and 10-mm antenna. Electrode temperature and impedance were measured simultaneously. After ablation, lesion length, width, and depth were measured with microcalipers, and volume calculated by a formula for ellipsoid bodies. Each energy delivery mode was tested in ten experiments. The deepest lesions were created with cooled energy delivery, and the largest volume by microwave energy delivery. Pulsed RF produced significantly deeper lesions than conventional RF energy delivery. Cooled or pulsed RF energy delivery created deeper transmural lesions than conventional RF. To create linear lesions at anatomically complex sites (isthmus), microwave energy seemed superior by rapidly creating deep and long lesions.

Animals↗
PubMed2005

A new algorithm for predicting triplet-triplet energy-transfer activated complex coordinate in terms of accurate potential-energy surfaces.

The new algorithm presented here allows, for the first time, the determination of the optimal geometrical distortions that an acceptor molecule in the triplet-triplet energy-transfer process undergoes, as well as the dependence of the activation energy of the process on the triplet energy difference of donor and acceptor molecules. This algorithm makes use of the complete potential-energy surfaces (singlet and triplet states), and contrasts with the first-order approximation already published [L. M. Frutos, O. Castano, J. L. Andres, M. Merchan, and A. U. Acuna, J. Chem. Phys. 120, 1208 (2004)] in which an expansion of the potential-energy surfaces was used. This algorithm is gradient based and finds the best trajectory for the acceptor molecule, starting from S(0) ground-state equilibrium geometry, to achieve the maximum variation of the singlet-triplet energy gap with the minimum energy of activation on S(0). Therefore, the algorithm allows the determination of a "reaction path" for the triplet-triplet energy-transfer processes. Also, the algorithm could also serve eventually to find minimum-energy crossing (singlet-triplet) points on the potential-energy surface, which can play an important role in the intersystem crossing process for the acceptor molecules to recover their initial capacity as acceptors. Also addressed is the misleading use of minimum-energy paths in T(1) to describe the energy-transfer process by comparing these results with those obtained using the new algorithm. The implementation of the algorithm is illustrated with different potential-energy surface models and it is discussed in the frame of nonvertical behavior.

Journal Article↗
PubMed2002

Energy intake and energy expenditure: a controlled study comparing dietitians and non-dietitians.

BACKGROUND: Underreporting of food intake has been commonly observed. We hypothesized that experience with recording dietary information might increase the accuracy of the records. To test this hypothesis, we compared energy intake and energy expenditure in dietitians-who are experienced in recording food intake-with those of non-dietitians, whose only exposure to training to record food was in the context of this trial. SUBJECTS/SETTING: Subjects for this study were 10 female registered dietitians and 10 women of comparable age and weight who were not dietitians. DESIGN: This study compared the energy intake obtained from 7-day food records with energy expenditure measured over the corresponding 7-day period using doubly labeled water. STATISTICAL ANALYSIS: Data were compared by an analysis of variance METHODS: All subjects were trained to provide a 7-day weighed food intake record. Energy expenditure was measured with doubly labeled water over the 7 days when the weighed food intake record was obtained. A total of 10 dietitians and a control of group of 10 women of similar age and weight were recruited for this study. Participants were told that the goal was to record food intake as accurately as possible, because it would be compared with the simultaneous measurement of energy expenditure determined by doubly labeled water. RESULTS: The energy expenditure of the dietitians and controls were not different (2,154+/-105 [mean+/- standard error of the mean] kcal/day for dietitians and 2,315 +/- 90 kcal/ day for controls). The dietitians underreported their energy intake obtained from the food records by an average of 223 +/- 116 kcal/day, which was not different from their energy expenditure. Participants in the control group, as hypothesized, significantly underreported their energy intake (429 +/- 142 kcal/day, P < .05). CONCLUSION: Dietitians estimated their energy intake more accurately than non-dietitians, suggesting that familiarity with and interest in keeping food records may lead to more reliable estimates of energy intake.

Adult↗