Energy balance whole body

At least three peptides are implicated in the regulation of food intake, energy expenditure, and whole-body energy balance in both rodents and humans and are found both peripherally as hormones and centrally. These are galanin, neuropeptide Y, and... 

Whole-body fatty-acid-balance methodology exploits the fact that in the absence of other n-3 PUFA, the diet is the only source of a-linolenate besides what is already present in the body. By comparing a-linolenate intake to accumulation of the sum of all n-3 PUFA determined over a balance period of several days to several weeks (deducting excretion and conversion to n-3 LC-PUFA). one can calculate a-linolenate disappearance or P-oxidation by difference. The advantages of the whole-body balance method are that (1) it reflects metabolism in the whole body rather than in an isolated tissue or subcel-lular compartment and (2) during energy deficit, this method alone can provide an estimate of a-linolenate oxidation derived from existing body stores as well as from the diet. 

In times of plenty, animals turn any carbohydrate that is surplus to their immediate energy requirements into fat. This fat can then be stored in various inconspicuous areas of the body (the usual place is in layers beneath the skin, where it serves the additional function of helping insulate the body from external temperature fluctuations) against the prospect of less cheerful days to come. If and when these lean days arrive, the fat depots are mobilized, the fat is transported to the liver, and there oxidized to provide energy. Some dietary fat, of course, is being broken down the whole time even in the normal, healthy animal, but it only really comes into its own as a major contributor to the overall energy-balance of the body when the animal is hard-pressed for carbohydrate, due to starvation, or when, as in diabetes, the metabolic... 

To the clinician, the accurate measurement of total body water (TBW) can provide indirect information concerning whole body composition and energy balance. Desiccation measurements performed on eviscerated guinea pigs in 1945 [270] led to the almost universal acceptance of the fact that lean body mass (LBM) was of constant composition — and additionally, contained all of the body water. Thus the extracellular water associated with adipose tissue was neglected and the water content of lean body mass taken as 73.2%. The following simple formula, which was readily applied to man, provided an indirect estimate of body fat ... 

Reynolds, C.K., H.F. Tyrrell and P.J. Reynolds, 1991. Effects of diet forage-to-concentrate ratio and intake on energy metabolism in growing beef heifers whole body energy and nitrogen balance and visceral heat production. J. Nutr. 121, 994-1003. 

A balanced diet constitutes not only of carbohydrates, fat and protein, but of water, dietary fibre, vitamins, minerals and micronutrients too. The demand of these diet components depends on various conditions like age and growth status, locomotor activity (work load), environmental temperature and probably on the season. The determination of the requirements of these nutrients under different conditions gives very important information on how to provide a balanced diet but to avoid ovemutrition. Whole body calorimetry is probably the most accurate and so the most important method both to estimate substrate and energy requirements and to calibrate other alternative methods to assess the energy metabolism like long-term heart rate measurements or the isotope dilution methods. 

The characterization of energy balance in cells and tissues relies upon the measurement of several variables oxygen and substrate consumption, lactate and carbon dioxide production. These measurements however give only indirectly and partly quantitative information about the energy balance in obesity. Whole body calorimetry and direct measurement of cell heat production have been introduced as a complement to the assessment of energy balance in the whole organism and energy expenditure on the cellular level. 

Thus the third principle simply asserts that, in its motion as a whole, a body does not know whether it is a mixture or not but in this paper the skeleton of the medium consists of a continuum with microstructure, as defined by Capriz (1989), and therefore it must satisfy balance equations there proposed. The first and the second principles affirm that the whole is no more than the sum of its parts and that the mixture s constituents, imagined as splitted in geometry, must be considered united in physics by suitable forces or energies, respectively. We should also notice how, unlike balance equations, constitutive proposals for dependent fields are usually affected by microstructural independent variables in addition to gross ones. 

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