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Call number: LD2668 .T4 1956 G53 / Master of Science

The purpose of this study was to examine the effects of a hypocaloric liquid diet, with varied protein/carbohydrate ratios, on two groups of male weightlifters. A maintenance diet was consumed by all subjects for one week prior to the experimental phase, and all subjects participated in a resistance weight training program. The experimental groups consumed either a moderate protein/high carbohydrate diet (MP/HC) with 0.8 g/kg body wt/d protein or high protein/moderate carbohydrate diet (HP /MC) with 1.6 g/kg body wt/d protein diet for the experimental week. Twenty-four hour urine samples were collected daily and two exercising sweat samples were taken for each subject. Fecal nitrogen losses were estimated and added to urine and sweat values for daily nitrogen excretion. There was a significant difference in nitrogen balance between the groups over time. Nitrogen balance was positive for the HP/MC group (4.13 g/d) and negative for the MP/HC group ( -3.19 g/d) . The results of this study suggest the possibility that weightlifters consuming a hypocaloric diet should consume more than the US RDA for protein to maximize retention of body protein. / M.S.

The nutritional needs of the renal patient vary as the renal function decreases. Little information exists concerning energy requirements for patients on hemodialysis. Renal failure has been called a wasting disease as evidenced by decreased body weight, body fat, arm circumference and serum proteins. This research was designed to help precisely define energy requirements for the hemodialysis subject. Resting energy expenditure (REE) was measured by indirect calorimetry in 17 male hemodialysis subjects whose mean age was 55 years at the Veterans Administration Medical Center in Hampton, Va. The Beckman MMC Horizon System, a portable device which permits the determination of heat production from gas exchange, oxygen consumption and carbon dioxide production was used. By regression analysis, the measured REE was compared to the basal energy expenditure (BEE): the ideal weight based on the Metropolitan Life Insurance tables, the current weight taken on day of indirect calorimetry, a non-dialysis day, and the post dialysis weight taken immediately after dialysis. A correlation analysis of the dependent variable, IEE, with the current, ideal and post dialysis BBE variable resulted in correlation coefficients of .3783, .0003, and .3946 respectively. None of these correlation coefficients were significantly correlated with the REE. The post dialysis variable had the highest correlation coefficient, and thus the strongest relationship to the REE. While any of the weights studied could be used to determine energy needs for the hemodialysis subject, post dialysis weight may be the most desirable choice. / M.S.

Body weight in mammals is defended so that small changes in weight evoke neuroendocrine and metabolic responses that encourage a return to one’s previous weight. While these homeostatic responses have been more commonly studied in the case of weight loss, our lab has developed a mouse model of overfeeding to study the physiology of defense against weight gain. In response to overfeeding-induced weight gain, the return to previous body weight is mediated primarily by a striking reduction in food intake, which persists until pre-overfeeding body weight is restored. However, preliminary data do not suggest activation of anorectic POMC neurons which reduce food intake or inhibition of the appetite stimulating AgRP or NPY neurons in the arcuate nucleus of the hypothalamus. Furthermore, we found that adipose tissue from overfed mice does not show the same inflammatory response as mice that have become obese slowly due to ad libitum high-fat diet (HFD) consumption. Paradoxically, despite the existence of mammalian systems that defend against weight gain, average body weight in humans has been on the rise over the last half century. Concomitant with the rise in obesity rates, has been increasing availability and consumption of processed and fast foods which are generally high in sugar, salt, and fat making them extremely palatable and calorically dense. Both the caloric density and enticing taste of the foods have been implicated in causing overconsumption and contributing to a rise in average body weight and prevalence of obesity. Thus, while controlling for caloric density we have investigated whether diet palatability can increase body weight and suppress defense against weight gain in mice. We designed our studies so that all diets were of the same caloric density and therefore varied only proportion of calories derived from fats, carbohydrates, and protein. Palatability is the relative subjective preference of one food over another; in our mouse studies we equated preference, when given, a choice with palatability. We confirmed that liquid diets sweetened with sucrose or the non-nutritive sweeteners sucralose and saccharin were preferred over non-sweetened diets. In 12 day feeding studies, although we found that sweetened diets were more palatable than unsweetened diets, they did not increase caloric intake or body weight. Next, we tested whether increasing percent calories from fat leads to increases in palatability or caloric intake. In a similar 12 day feeding preference study, we found diets higher in percent calories from fat (high-fat diet = HFD) were preferred to diets with lower percent calories from fat (low-fat diet = LFD) and that the access to a HFD increased caloric intake and body weight. Employing a four-week single diet feeding study, we also found a linear relationship between percent calories from fat and caloric intake consistent with our hypothesis that percent calories from fat is sensed and modulates caloric intake. To test whether HFD can suppress defense of body weight, we used an overfeeding paradigm which I help develop, to test whether ad libitum access to a HFD prevented a return to the original body weight following overfeeding. HFD did attenuate the hypophagic response to overfeeding and prevented a return to each mouse’s initial weight with the mice having access to the HFD mice stabilizing at a higher body weight. Palatability has traditionally been ascribed to sensing of smell and taste, however, macronutrients can also be sensed within intestinal tract. To determine whether the effects of percent calories from fat require naso-oral sensing to modulate feeding behavior, we used an intragastric feeding system to bypass taste and smell and deliver HFD directly into the stomach of mice. Even in the absence of oropharyngeal sensing, HFD in the gut was sufficient to increase ad libitum caloric intake of a low-fat diet and increase body weight. Finally, based on our findings of post-oral fat sensing driving caloric intake, we tested whether post-oral sensing of percent calories from fat was sufficient to condition a flavor preference. However, we found that when caloric density was controlled, a high percent calories from fat was not sufficient to condition a flavor preference.

The effects of two hypocaloric diets on body weight (BW), percent body fat (%BF), lean body mass (LBM) and static muscular endurance were studied in college aged experienced male weightlifters for 7 days. Nineteen (X age = 20.6) volunteers were randomly assigned to one of three groups: control (n=5), High Protein/Moderate Carbohydrate - HP/MC (n=7) or Moderate Protein/High Carbohydrate - MP/HC (n=7). The two hypocaloric groups consumed 18 kcal/kg body weight for 7 days. The HP/MC group's diet contained 1.6 g/kg body weight/day of protein while the MP/HC group consumed 0.8 g/kg body weight/day of protein. Fat content of both diets was approximately equal so that carbohydrate content varied inversely with protein content. The control group was asked to follow a weight maintenance diet. All groups followed a similar supervised weight training regimen approximately 2 hours per day, six of the seven days of the study. Analysis of variance revealed that weight loss for the control group was not significant over the seven day experiment but that the two experimental groups showed a similar significant decrease in body weight of 3.6 kg for the HP/MC group and 4.0 kg for the MP/HC group. %BF of all subjects was significantly lower over the 7 day study using both skinfold measurements and hydrostatic weighing but there was no significant difference between the groups. LBM losses calculated from skinfold measurements were seen over time for all subjects and a significant interaction showed the 2 experimental groups to lose significantly more LBM over the 7 day study. LBM determined from hydrostatic weighing produced losses as well, but no differences were noted between the groups. All groups experienced quadricep endurance decrements over the 7 day study, but did not differ from each other. No significant changes were found for bicep endurance. It was concluded that neither the HP/MC diet nor the MP/HC diet was effective for maintaining LBM or quadricep endurance. However, both diets did produce significant losses in BW and %BF over the week long study. / M.S.

Twelve obese young women (aged 22-36) were studied to determine the·effects of the combination of an exercise program with either a high carbohydrate (HC) hypocaloric diet or low carbohydrate (LC) hypocaloric diet on total cholesterol, high density lipoprotein (HDL) cholesterol and triglycerides. Subjects were randomly placed in one of the diet groups (530 kcal/day) and participated in submaximal (60% VO₂ max) exercise sessions three times per week for a period of 28 days. After the treatment period, the subjects consumed a 1000 kcal/day mixed diet for one week while continuing the exercise program. Blood samples were drawn weekly for the analysis of total cholesterol, HDL cholesterol and triglycerides. Weight significantly decreased in both groups (mean decrease = 9.8% for LC; 8.8% for HC). After week one of the diet, total cholesterol and HDL cholesterol decreased significantly throughout the rest of the study. Due to the changes in total cholesterol, the total cholesterol/HDL cholesterol ratio decreased throughout the study, reaching significance by the post-treatment period when the ratio was 20.6% below baseline levels for both groups. There were no significant changes in triglycerides for either group. However, triglycerides increased throughout the dietary treatment (mean increase 9.5% for LC; 18.7% for HC). Triglyceride concentrations also changed during the post-treatment week as the LC group had a mean decrease of 38.3% and HC group, 8.2% from baseline values. These data suggest that both diets are equally effective in reducing body weight in young women. Also, in spite of the decreases noted in HDL cholesterol in both groups, total cholesterol decreased even further, thus producing a lower, more favorable total cholesterol/HDL cholesterol ratio. / Master of Science

The null hypothesis for this study was there were no differences in caloric intake, cholesterol, and sodium intakes of food prepared at home as contrasted with food prepared outside of the home when consumed by men 45-54 years old. The three dietary intakes have been associated with medical conditions that cause death in humans. This study provided information which could enable nutrition educators, foodservice managers, and men aged 45-54 who are employed at a factory to understand how consumption of these three intakes differs when foods were prepared at home as contrasted with outside of the home. Therefore, this study provided information to help lower the risk factors of heart diseases, hypertension, and obesity which are associated with caloric intake, cholesterol and sodium consumption.Participants completed three days of food frequencies and dietary records. The Sign Test was used to analyze the differences between food prepared at homeand outside of the home for caloric, cholesterol, and sodium intakes.Statistical analysis of the data revealed:(1) A significant difference in caloric intake of food prepared at home as contrasted with food prepared outside of the home when consumed by men 45-54 years old (p < 0.05).(2) No significant difference in cholesterol intake of food prepared at home as contrasted with food prepared outside of the home when consumed by men 45-54 years old (p > 0.05).(3) No significant difference in sodium intake of food prepared at home as contrasted with food prepared outside of the home when consumed by men 45-54 years old (p > 0.05). / Department of Home Economics