The relationship between dietary energy density and energy intake

Much of the research in ingestive behavior has focused on the macronutrient composition of foods; however, these studies are incomplete, or could be misleading, if they do not consider the energy density (ED) of the diet under investigation. Lowering the ED (kcal/g) by increasing the volume of preloads without changing macronutrient content can enhance satiety and reduce subsequent energy intake at a meal. Ad libitum intake or satiation has also been shown to be influenced by ED when the proportions of macronutrients are constant. Since people tend to eat a consistent weight of food, when the ED of the available foods is reduced, energy intake is reduced. The effects of ED have been seen in adults of different weight status, sex, and behavioral characteristics, as well as in 3- to 5-year-old children. The mechanisms underlying the response to variations in ED are not yet well understood and data from controlled studies lasting more than several days are limited. However, both population-based studies and long-term clinical trials indicate that the effects of dietary ED can be persistent. Several clinical trials have shown that reducing the ED of the diet by the addition of water-rich foods such as fruits and vegetables was associated with substantial weight loss even when patients were not told to restrict calories. Since lowering dietary energy density could provide effective strategies for the prevention and treatment of obesity, there is a need for more studies of mechanisms underlying the effect and ways to apply these findings.     

Detecting electron beam energy shifts with a commercially available energy monitor

Routine electron beam quality assurance requires an accurate, yet practical, method of energy characterization. Subtle shifts in beam energy may be produced by the linac bending magnet assembly, and the sensitivity of a commercially available electron beam energy-monitoring device for monitoring these small energy drifts has been evaluated. The device shows an 11% change in signal for a 2 mm change in the I50 energy parameter for low energy electron beams (in the vicinity of 6 MeV) and a 2.5% change in signal for a 2 mm change in the I50 energy parameter for high energy electron beams (in the vicinity of 22 MeV). Thus the device is capable of detecting small energy shifts resulting from bending magnet drift for all clinically relevant electron beams.     

Effects of energy density of daily food intake on long-term energy intake

An important question that has been raised recently is whether it is mainly the energy density (ED) of the food consumed or its macronutrient composition that determines daily energy intake (EI). In this scope, the effect of ED on EI has been assessed in short-term as well as long-term experiments. Over the short term, i.e., during a meal, it was found that ED affects EI directly; then subjects mainly monitor the weight of the food ingested. Over the long term, the effects of ED on EI are modulated. Average daily energy intake (ADEI) does not only consist of meals but also includes snacks and drinks. ADEI appears to be related to ED of the food and drinks where ED is at least determined by specific macronutrients (primarily fat and carbohydrate), but not when ED is determined only by the weight of water. With respect to the separate effects of the ED of foods and of drinks on ADEI, only ED from foods had a significant relationship with total EI. Moreover, during daily food intake, subjects seem to adapt their portion sizes to estimated EDs. Long-term studies have shown that dietary restraint compensates for the effect of increases in ED on ADEI, whereas unrestrained eaters compensate for the effect of decreases in ED on ADEI. In conclusion, ED determines short-term EI. This cannot be extrapolated to the long term because only the ED of food, and not the ED of drinks, determines total EI. In addition, over the long term, the short-term effect is modulated by dietary restraint and adapted portion sizes. ED is not a universal concept that determines EI, yet rather a characteristic of the macronutrients: mainly fat and carbohydrate contributing to variation in EI.     

A cartography of energy medicine: From subtle anatomy to energy physiology

The field of energy medicine (EM) is perhaps the most controversial branch of integrative medicine. Its core concept - the existence of an invisible healing energy – has not yet been validated by Western medicine, and the mechanism(s) of action of its techniques have not been fully elucidated. This paper addresses these problems by marshalling several types of evidence: basic science research into electromagnetic fields (EMF), subjective sensations experienced when receiving EM treatments, and clairvoyant perceptions of EM in action. The latter two sources of information, while not solid enough to meet current standards of scientific rigor, can nonetheless generate important new information. A hypothesis is then developed to explain these findings.First, the main components of the human subtle energy system are presented: the “subtle anatomy” of the meridians, of the energy centers and of the biofield. Several representative EM techniques are then analyzed to determine which specific components of that energy structure they impact. Next, EM's mechanisms of action are explored by describing how these altered energy dynamics can affect biologic processes. This subject is termed “energy physiology”, in parallel with conventional medicine's foundation in anatomy and physiology. Finally, potential research into energy physiology is outlined that focuses on several common but distinctive experiences which are not fully explained by the current mechanistic biomedical model. Plausible and testable energy-based explanations are proposed for phantom limb pain, emotional entrainment in groups, unusually rapid symptom response to EM, and the invisible templates that guide cell growth and differentiation.This analysis is intended to serve as a guide to future clinical and research explorations into the multidimensional nature of human beings. As Western medicine develops technologies that can generate objective empiric evidence in these subtle domains, we will be able to more fully understand the energetic components of health and illness.     

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).     

Modular organization of cardiac energy metabolism: energy conversion,transfer and feedback regulation

To meet high cellular demands, the energy metabolism of cardiac muscles is organized by precise and coordinated functioning of intracellular energetic units (ICEUs). ICEUs represent structural and functional modules integrating multiple fluxes at sites of ATP generation in mitochondria and ATP utilization by myofibrillar, sarcoplasmic reticulum and sarcolemma ion‐pump ATPases. The role of ICEUs is to enhance the efficiency of vectorial intracellular energy transfer and fine tuning of oxidative ATP synthesis maintaining stable metabolite levels to adjust to intracellular energy needs through the dynamic system of compartmentalized phosphoryl transfer networks. One of the key elements in regulation of energy flux distribution and feedback communication is the selective permeability of mitochondrial outer membrane (MOM) which represents a bottleneck in adenine nucleotide and other energy metabolite transfer and microcompartmentalization. Based on the experimental and theoretical (mathematical modelling) arguments, we describe regulation of mitochondrial ATP synthesis within ICEUs allowing heart workload to be linearly correlated with oxygen consumption ensuring conditions of metabolic stability, signal communication and synchronization. Particular attention was paid to the structure–function relationship in the development of ICEU, and the role of mitochondria interaction with cytoskeletal proteins, like tubulin, in the regulation of MOM permeability in response to energy metabolic signals providing regulation of mitochondrial respiration. Emphasis was given to the importance of creatine metabolism for the cardiac energy homoeostasis.     

Ultrasonic energy in endoscopic surgery

The Harmonic Scalpel made by Ultracision is a system for endoscopic cutting. The energy source is vibration. The power box is attached to a forceps or blade, and the vibrational frequency of the blade approaches 55,500 cycles/second. This causes a knife-like action of the blade through tissue, with enough heating to create coagulation of small vessels. When this vibration energy is applied to the forceps configuration, coagulation occurs. By rotating the bottom blade of the forceps, the instrument becomes like a pair of scissors, and the tissue can divide. The Harmonic Scalpel allows the operator to cut using a tactile tissue. No smoke is created, only microaromized water droplets which are rapidly absorbed by the peritoneak surface. The instrument is extremely safe in that only tissue which is touched is cut; the energy source cannot travel through air, such as can happen with electrosurgery and laser surgery.     

Review of the effects of dilution of dietary energy with olestra on energy intake

The non-absorbable substitute for dietary triacylglycerol, olestra, has been marketed in the United States for fifteen years. Olestra is comprised of sucrose with six to eight of its hydroxyl groups forming ester links with long-chain fatty acids. Because olestra is not hydrolyzed by fat-splitting enzymes in the small intestine, it is not absorbed from the small intestine into blood and tissues, and therefore provides no energy that can be utilized by the body. The hedonic properties of olestra with a specific fatty acid composition are similar to those of a triacylglycerol with the same fatty acid composition. Its use by consumers has been restricted by federal regulation to the commercial preparation of savory snack food items, principally as a frying medium for potato chips. An important question about the substitution of olestra for absorbable fat in the diet is whether the consumer will sense that a smaller amount of energy has been ingested. If it is sensed, thereby providing no satiation, then consuming additional energy in later meals will compensate for the removal of absorbable energy from the diet. If it is not sensed at all, then there is no compensation, and the person reduces caloric intake. This review first summarizes studies with olestra that have focused on its effect on the physiology of appetite. In general these studies have demonstrated that olestra does not influence signals of satiation including cholecystokinin and stomach emptying. The review then discusses studies of food consumption in experimental animals in which olestra was substituted for fat in the diet. Rodents have been repeatedly observed to compensate completely for the substitution of olestra for normal fat by eating more total diet. Most studies of the effect of olestra on human satiation have found incomplete or no compensation through additional energy consumption when olestra was substituted for dietary fat. In two clinical studies, however, complete compensation was observed, suggesting that experimental conditions and individual variability influence the ability to sense the substitution of olestra for absorbable fat. There is no evidence that dietary olestra causes consumption of more energy than would have been consumed without olestra in the diet. The data from animals and humans strongly suggest that the rodent is not a satisfactory model for the human in the determination of the extent of compensation by substitution of olestra for dietary fat.     

Mean energy in electron beams

The mean energy of the energy spectrum is an essential parameter for the dosimetry of therapeutic electron beams. Frequently it is assumed that the mean energy of such beams remains constant across the beam and only its degradation with depth is considered. The present work analyzes the variation of the mean energy of primary electrons with depth and lateral position in an electron beam using the Monte Carlo method. Results are compared with relations commonly employed for determination of mean energy at a depth. For the variation of the mean electron energy with depth in broad beams, good agreement was found between Monte Carlo results and an analytic continuous slowing down expression, which takes the variation of radiation stopping power with depth into account. Due to the calculated lateral variation of the mean energy, the relative absorbed dose profile determined with an air ionization chamber in a clinical beam should differ by less than 1% from the measured ionization profile.     

Ultrasonic energy backscattered from blood

To determine how the ultrasonic energy scattered from flowing blood depends on the hematocrit, the rms amplitude of the audio Doppler signal from a range gated, pulsed Doppler ultrasonic flowmeter was measured for hematocrits ranging from 0.01 to 80%. For all investigated frequencies (5–27 MHz), the signal power, the square of the rms amplitude, was proportional to the hematocrit until 2%, reached a plateau at 10%, and was independent of the hematocrit over the rest of the investigated range. To determine how the scattered energy depends on the volume of the erythrocyte, we measured the variation of audio signal power with cell concentration for goat blood, and then without changing any of the instrument settings, repeated this measurement for dog blood. For cell concentrations ranging from 10⁴ to 10⁶ cells/mm³, the larger dog erythrocytes scattered 17 times more energy than the goat erythrocytes. This observation is consistent with the hypothesis that the energy scattered by a single erythrocyte is proportional to the square of the volume of the cell. This project was supported in part by NHLI Grant HL 18977-02. This work was completed while Dr. Borders was a student in the Department of Applied Mechanics and Engineering Sciences (Bioengineering), University of California, San Diego.     

Dairy beverages and energy balance

High dairy intakes have been associated with lower rates of obesity in observational studies, but mechanisms to explain the association are lacking. A high intake of dairy protein reduces spontaneous food intake and may be one important mechanism, but more specific effects of dairy calcium seem to exist.We have found that high versus low calcium intakes from dairy products had no effect on 24-h energy expenditure or substrate oxidation rates, but fecal fat excretion increased ∼ 2.5-fold on the high-calcium diets. In a meta-analysis of intervention studies we found that increasing dairy calcium intake by 1200 mg/day resulted in increased fecal fat excretion by 5.2 (1.6-8.8) g/day.Newer research shows that humans possess taste receptors for calcium in the gastrointestinal tract and that signaling may be linked to appetite regulation. A new line of evidence suggests that an inadequate calcium intake during an energy restricted weight loss program may trigger hunger and impair compliance to the diet.These mechanisms may be part of the explanation for the protective effects of dairy products with regard to obesity and metabolic syndrome.