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Studies on energy metabolism in man
Başlık:
Studies on energy metabolism in man
Yazar:
Rosenberg, Kathryn Ann, author.
ISBN:
9780438059078
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (230 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 76-08C.
Advisors: J. V.G.A Durnin.
Özet:
In the first investigation, the response of men and women to three days of total fasting was investigated. The amount of protein catabolized during the fast and during the preceding twenty-four hours was assessed by collection of urine and measurement of nitrogen output. In addition, the subjects had their body composition measured both by the technique of underwater weighing and by the measurement of skinfold thicknesses. Resting metabolic rate was measured by indirect calorimetry on each day of the fast and daily energy expenditure was estimated by use of the timed diary technique. The energy metabolism of the subjects during the fast was compared between the men and women. The contribution of protein both to resting expenditure and to the total energy expenditure of the men and women was seen to be similar. The nitrogen output, after normalization for body size, was almost identical for the group of men when compared to the group of women. This was true for several methods of standardization including body weight, fat free mass, surface area, and basal energy expenditure. This result failed to confirm suggestions from earlier work that women enjoyed an advantage over men in a sparing of body protein during food deprivation. The data on nitrogen output for the men and women was combined and the results for the group as a whole were analyzed on a bivariate basis to assess the relationship between nitrogen excretion and the various measures of body size, composition and energy expenditure. Regression analysis showed fat free mass to be the best predictor of nitrogen excretion. A correlation coefficient of 0.86 was obtained for the relationship between fat free mass and nitrogen excretion on the third day of the fast. Multiple regression analysis with fat free mass, basal energy expenditure, urine output and body weight as independent variables led to a multiple correlation coefficient of 0.94. It was concluded that during a fast of short duration, it is primarily body size, independent of sex, which determines the degree of protein catabolism. This lack of a sex difference is discussed in light of suggestions of a difference in published results. The poor relationship of body fat content to protein catabolism was also discussed from the point of view of published statements suggesting an inverse relationship. The second investigation attempted to resolve the contradictory results in the literature concerning the effect of alcohol on resting metabolic rate (RMR). Two series of experiments were carried out. In the first, RMR was measured by indirect calorimetry before and after meals of food, food plus alcohol, and alcohol alone. The subjects were selected with the intention of minimizing the variability of RMR. In the second series, subjects had their RMR measured before and after larger doses of alcohol or meals of food of the same energy content. The analysis of the results led to the conclusion that the group of subjects in the first series showed a significant increase in metabolic rate after the alcohol as they had after the food. In the second series, the subjects appeared to respond in a comparable manner both to the alcohol alone and to the food. That is, certain individuals showed a significant increase in metabolic rate after both types of meal and others showed no increase to either. An attempt to account for the contradictory results in the literature is made, and the general problems concerning the quantification and explanation of specific dynamic action are discussed. Thirdly, the sensitivity of the commonly used Weir's Formula to respiratory quotient in the conversion of respiratory exchange values to energy expenditure is discussed and quantified. The occurrence of labile and metabolically unrepresentative RQ's during short term measurements of gas exchange is documented. The lack of necessity for the measurement of carbon dioxide output when using Weir's formula means that grossly misleading RQ's go undetected. They do, however, introduce errors into the conversion to energy expenditure values when the formula is being used. The magnitude of these errors and the means whereby they enter into the calculation are discussed.
Notlar:
School code: 0547
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(684684.1) | 684684-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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