Effects of macronutrient and caloric content of the diet on circulating concentrations of ghrelin and other hormones involved in energy metabolism

Investigating the role of ghrelin and hormones involved in energy metabolism on energy balance and body composition when varying diets and caloric contents are consumed could provide insight into the etiology of obesity and related diseases. In this dissertation, I investigated the effect of Atkins and AHA diets in normal weight and overweight women and men in both the fed and fasted states on the change in circulating concentrations of ghrelin (acylated and total), adiponectin, glucagon, growth hormone, insulin, and leptin before and after consuming lunch and over waking hours (07:00 to 22:00). Eight subjects, ages 20 –32, participated in each study: four normal subjects with a normal BMI and four overweight subjects with an overweight BMI. Each subject received both diets by a crossover design. Two normal and two overweight subjects were assigned to each diet. The Atkins\u27 diet contained 10% of energy as carbohydrate, 45% of energy as protein, and 45% of energy as lipid, and the AHA diet contained 63% of energy as carbohydrate, 12% of energy as protein, and 25% of energy as lipid. Diets were isocaloric. Each diet was fed for 14 days, and then subjects switched to the other diet. Blood was taken every hour from 7 am to 9 pm on days 13 and 27 of the study. Plasma samples were analyzed for active and total ghrelin, leptin, insulin, glucagon, growth hormone, and adiponectin. Lunch results: in women, acylated ghrelin concentrations were influenced by the interaction of diet and weight. Men consuming the AHA diet had an increase in acylated ghrelin concentrations over the lunch period, whereas, there was no change in acylated ghrelin concentrations in men consuming the Atkins diet. Women and men consuming the Atkins diet had higher glucagon concentrations before lunch. When consuming the AHA diet, overweight women had a greater increase in insulin that of normal weight women. In overweight women, the change in insulin concentrations was greater when the AHA diet was consumed in comparison to the Atkins diet. Result for 14-hour study: acylated ghrelin did not have preprandial increases before breakfast and lunch with varied responses before dinner in overweight and normal weight women fed either the Atkins or AHA diets in both sequences. Plasma glucagon was greater after lunch through the end of the 14– hour period in women consuming the Atkins diet. Insulin concentrations were higher and had greater responses to meal ingestion in women consuming the AHA diet in comparison to the Atkins diet. Men consuming the AHA diet in period 2 had increased acylated ghrelin and total ghrelin concentrations in comparison to when the men consumed the Atkins diet. Insulin concentrations were suppressed in men consuming the Atkins diet in comparison to men consuming the AHA diet. Glucagon concentrations were higher in men consuming the Atkins diet in comparison to the AHA diet after lunch until the end of the study period (hours 7 –14). Weight class affected some hormone concentrations different and thus women and men in overweight and normal weight classes were analyzed separately. Each class of macronutrients influences circulating hormone concentrations. Experimental design is critical in obtaining information on the relationship of hormones related to appetite and body composition. Our results indicate that current recommendations may not be appropriate for all individuals as men and women both normal weight and overweight have different hormone responses to the macronutrient content of the diet

Plane of Nutrition Affects Plasma Ghrelin Concentrations in Neonatal Calves

Investigating different planes of nutrition on appetiterelated hormones could provide knowledge into the role of these hormones on growth performance in neonatal calves. The objective of the current study was to investigate the effects of feeding rates on ghrelin in plasma from preruminant calves. Treatments (n = 8 per treatment) were designed to achieve three targeted daily rates of gain (No Growth = 0.0 kg, Low Growth = 0.55 kg, or High Growth = 1.2 kg) in live weight over a 7-wk period. All calves were fed a 30% crude protein, 20% fat, all-milk protein milk replacer reconstituted to 14% dry matter. Daily growth rates for No, Low, and High Growth calves were different (P\u3c 0.001) throughout the experimental period and averaged 0.11 ± 0.02 kg, 0.58 ± 0.02 and 1.16 ± 0.04 kg, respectively. Fasting ghrelin active concentration was higher (P \u3c 0.0001) in the No Growth calves over the 7-wk period in comparison to the Low and High growth calves. Circulating concentrations of ghrelin in neonates fed different planes are similar to responses of adult humans to feed intake. These results indicate an inverse relationship of ghrelin active concentration with respect to plane of nutrition and growth rate in neonates

The Effectiveness of MyPlate and Paleolithic-based Diet Recommendations, both with and without Exercise, on Aerobic Fitness, Muscular Strength and Anaerobic Power in Young Women: A Randomized Clinical Trial

International Journal of Exercise Science 11(2): 921-933, 2018. The purpose of this study was to evaluate the effectiveness of recommending a MyPlate or a Paleolithic-based diet, both with and without exercise, on aerobic fitness, strength, and anaerobic power over eight weeks. Participants (n=20) were randomized to one of four groups, (1) a MyPlate diet (MP), (2) Paleolithic-based diet (PD), (3) MyPlate and exercise (MP + Ex), and (4) Paleolithic-based diet and exercise (PD + Ex). The exercise included two days of unsupervised aerobic and resistance exercise. At baseline and final, absolute and relative peak oxygen consumption (absVO2peak and relVO2peak), anaerobic power, and upper and lower body strength were determined. Data were analyzed using repeated measures two-way analysis of variance (ANOVA). The ANOVA indicated that there was no significant interaction between time point (TP)*diet (D)*exercise (Ex) for all variables except relVO2peak (p = 0.016). The MP + Ex group (Δ+4.4 ml×kg-1×min-1) had a greater change from baseline compared to the MP group (Δ-2.7 ml×kg-1×min-1, p = 0.002), and PD + Ex group (Δ-0.3 ml×kg-1×min-1, p = 0.03). The results suggest recommending a MyPlate diet with both aerobic and resistance training are effective at improving aerobic fitness when compared to PD recommendations with exercise, although these conclusions may be confounded by low compliance to exercise recommendations

Effects of Dietary Macronutrients on Appetite-Related Hormones in Blood on Body Composition of Lean and Obese Rats

Investigating the role of appetite-related hormones on energy balance and body composition when varying diets are consumed could provide insight into the etiology of obesity. Fifty-three adult male Sprague Dawley and 30 adult male Zucker Fatty rats were assigned randomly to one of five diets: Control, 75% control, American Heart Association (AHA), Atkins, or high fat (HF). Diets were fed for five weeks. Weekly plasma samples were collected and analyzed for ghrelin, leptin, insulin, and adiponectin. Terminal plasma samples were analyzed for ghrelin, leptin, insulin, glucagon, oxyntomodulin, adiponectin, and blood metabolites. Our results indicate that macronutrient composition of the diet influences appetite-related hormones differently in genetically divergent rats. For example, glucagon concentration was higher in obese rats fed the Atkins diet in comparison to obese rats fed the HF and 75% control diets (P\u3c0.05) and tended to be higher in obese rats fed the Atkins diet in comparison with rats fed the AHA and control diets (0.0

Nutrient Regulation of Plasma Ghrelin Concentration in Lean and Overweight Female Humans

Investigating the role of appetite-related hormones on energy balance and body composition when varying diets are consumed could provide insight into the etiology of obesity. Eight female subjects, ages 20–30, were used in this study: four normal subjects with body mass index (BMI) of 19–24 and four overweight/obese subjects with of BMI of 27–30. Each subject received both treatments by a crossover design. Two normal and two overweight subjects were assigned to the Atkins’ diet. The Atkins’ diet contained 10% of energy as carbohydrate, 45% of energy as protein, and 45% of energy as lipid. The remaining two normal and two overweight subjects were assigned to the AHA diet that contained 63% of energy as carbohydrate, 12% of energy as protein, and 25% of energy as lipid. Each diet was fed for 14 days, and then subjects were switched to the other diet. We hypothesized that subjects consuming the Atkins’ diet would have lower plasma ghrelin concentrations than subjects consuming the AHA diet. On days 6 and 20, blood was taken at one hour before and after the noon meal. Blood was taken every hour from 7 am to 9 pm on days 13 and 27 of the study. On days 14 and 28, subjects were fasted from 7 am to 12 pm and fed their meal at noon. Two blood samples were taken on days 14 and 28 at 11 am and one hour after the meal. All plasma samples were analyzed for ghrelin. Normal weight women consuming the Atkins diet had lower fasting ghrelin concentrations than did women consuming the AHA diet (p=0.0141). Ghrelin concentrations in overweight women were not significantly different (p=0.8076). These results indicate a relationship of appetite-related hormones with respect to diet composition

Effect of Feed Intake on Plasma Ghrelin Concentration in Beef Cattle

Two experiments were conducted to determine if ghrelin mRNA existed in ruminant digestive tract tissues and to establish the fluctuation in plasma ghrelin concentrations for fed and fasting steers. Tissues collected from the ruminant digestive tract indicate detectable ghrelin mRNA in the upper, middle, and lower portion of the abomasum and in the small intestine but no detectable ghrelin mRNA in the reticulum, omasum, and rumen. Plasma ghrelin concentrations are elevated by a fasting period that is as short as 22 h. Additionally, plasma ghrelin remain elevated throughout a 48-h fasting period. The magnitude of difference in plasma ghrelin concentration between the fed and fasting states warrants further investigation as to the impact that this fluctuation in hormone concentration has on feed intake, composition of gain, and energy expenditure in cattle

Effect of Ghrelin Injection on Blood and Body Composition in Rats

Ghrelin has been reported to cause hyperglycemia in humans and adiposity in rodents. The objective of trial one was to test the effects of ghrelin on blood and body composition in rats. The objective of trial two was to evaluate the effect of two doses of ghrelin on blood and body composition. Trial One: Adult male Sprague Dawley rats were administered 1 μg/rat ghrelin in 0.15 M NaCl or vehicle (0.15 M NaCl) every morning for 30 days. The terminal blood sample was analyzed for glucose, urea nitrogen, and nonesterified fatty acids concentrations. The carcasses were analyzed for total lipid and nitrogen content. Blood urea nitrogen, nonesterified fatty acids, carcass total lipid, and carcass total nitrogen concentrations were similar for the control and ghrelin groups. However, blood glucose concentration tended to be higher in the ghrelin group than in the control. Ghrelin administered at 2.4 μg/kg did not cause adiposity in rats but did tend to cause hyperglycemia. Trial Two: Adult male Sprague Dawley rats were administered 1 μg/rat ghrelin, 20 μg/rat ghrelin, or vehicle every morning for 30 days. The terminal blood sample was analyzed for glucose and cholesterol concentrations. The carcasses were analyzed for total lipid and nitrogen content. Carcass total nitrogen concentrations were similar for the control and ghrelin groups. Carcass percent lipid was higher in the 1 μg/rat ghrelin group (P = 0.04). Feed intake among all three groups was the same. Blood glucose concentration, however, tended to be higher in the ghrelin groups than in the control. Blood cholesterol concentration was lower in the ghrelin treated animals. In the second trial, ghrelin injection of 1 μg/rat did cause an increase in adiposity whereas 20 μg/rat did not cause an increase in adiposity. Both ghrelin treatments tended to cause hyperglycemia in rats. In summary, ghrelin increased blood glucose concentration without changing body composition

Effects of macronutrient and caloric content of the diet on circulating concentrations of ghrelin and other hormones involved in energy metabolism

Investigating the role of ghrelin and hormones involved in energy metabolism on energy balance and body composition when varying diets and caloric contents are consumed could provide insight into the etiology of obesity and related diseases. In this dissertation, I investigated the effect of Atkins and AHA diets in normal weight and overweight women and men in both the fed and fasted states on the change in circulating concentrations of ghrelin (acylated and total), adiponectin, glucagon, growth hormone, insulin, and leptin before and after consuming lunch and over waking hours (07:00 to 22:00). Eight subjects, ages 20 –32, participated in each study: four normal subjects with a normal BMI and four overweight subjects with an overweight BMI. Each subject received both diets by a crossover design. Two normal and two overweight subjects were assigned to each diet. The Atkins' diet contained 10% of energy as carbohydrate, 45% of energy as protein, and 45% of energy as lipid, and the AHA diet contained 63% of energy as carbohydrate, 12% of energy as protein, and 25% of energy as lipid. Diets were isocaloric. Each diet was fed for 14 days, and then subjects switched to the other diet. Blood was taken every hour from 7 am to 9 pm on days 13 and 27 of the study. Plasma samples were analyzed for active and total ghrelin, leptin, insulin, glucagon, growth hormone, and adiponectin. Lunch results: in women, acylated ghrelin concentrations were influenced by the interaction of diet and weight. Men consuming the AHA diet had an increase in acylated ghrelin concentrations over the lunch period, whereas, there was no change in acylated ghrelin concentrations in men consuming the Atkins diet. Women and men consuming the Atkins diet had higher glucagon concentrations before lunch. When consuming the AHA diet, overweight women had a greater increase in insulin that of normal weight women. In overweight women, the change in insulin concentrations was greater when the AHA diet was consumed in comparison to the Atkins diet. Result for 14-hour study: acylated ghrelin did not have preprandial increases before breakfast and lunch with varied responses before dinner in overweight and normal weight women fed either the Atkins or AHA diets in both sequences. Plasma glucagon was greater after lunch through the end of the 14– hour period in women consuming the Atkins diet. Insulin concentrations were higher and had greater responses to meal ingestion in women consuming the AHA diet in comparison to the Atkins diet. Men consuming the AHA diet in period 2 had increased acylated ghrelin and total ghrelin concentrations in comparison to when the men consumed the Atkins diet. Insulin concentrations were suppressed in men consuming the Atkins diet in comparison to men consuming the AHA diet. Glucagon concentrations were higher in men consuming the Atkins diet in comparison to the AHA diet after lunch until the end of the study period (hours 7 –14). Weight class affected some hormone concentrations different and thus women and men in overweight and normal weight classes were analyzed separately. Each class of macronutrients influences circulating hormone concentrations. Experimental design is critical in obtaining information on the relationship of hormones related to appetite and body composition. Our results indicate that current recommendations may not be appropriate for all individuals as men and women both normal weight and overweight have different hormone responses to the macronutrient content of the diet.</p

Effects of Dietary Macronutrients on Appetite-Related Hormones in Blood on Body Composition of Lean and Obese Rats

Investigating the role of appetite-related hormones on energy balance and body composition when varying diets are consumed could provide insight into the etiology of obesity. Fifty-three adult male Sprague Dawley and 30 adult male Zucker Fatty rats were assigned randomly to one of five diets: Control, 75% control, American Heart Association (AHA), Atkins, or high fat (HF). Diets were fed for five weeks. Weekly plasma samples were collected and analyzed for ghrelin, leptin, insulin, and adiponectin. Terminal plasma samples were analyzed for ghrelin, leptin, insulin, glucagon, oxyntomodulin, adiponectin, and blood metabolites. Our results indicate that macronutrient composition of the diet influences appetite-related hormones differently in genetically divergent rats. For example, glucagon concentration was higher in obese rats fed the Atkins diet in comparison to obese rats fed the HF and 75% control diets (P<0.05) and tended to be higher in obese rats fed the Atkins diet in comparison with rats fed the AHA and control diets (0.06</p

Nutrient Regulation of Plasma Ghrelin Concentration in Lean and Overweight Female Humans

Investigating the role of appetite-related hormones on energy balance and body composition when varying diets are consumed could provide insight into the etiology of obesity. Eight female subjects, ages 20–30, were used in this study: four normal subjects with body mass index (BMI) of 19–24 and four overweight/obese subjects with of BMI of 27–30. Each subject received both treatments by a crossover design. Two normal and two overweight subjects were assigned to the Atkins’ diet. The Atkins’ diet contained 10% of energy as carbohydrate, 45% of energy as protein, and 45% of energy as lipid. The remaining two normal and two overweight subjects were assigned to the AHA diet that contained 63% of energy as carbohydrate, 12% of energy as protein, and 25% of energy as lipid. Each diet was fed for 14 days, and then subjects were switched to the other diet. We hypothesized that subjects consuming the Atkins’ diet would have lower plasma ghrelin concentrations than subjects consuming the AHA diet. On days 6 and 20, blood was taken at one hour before and after the noon meal. Blood was taken every hour from 7 am to 9 pm on days 13 and 27 of the study. On days 14 and 28, subjects were fasted from 7 am to 12 pm and fed their meal at noon. Two blood samples were taken on days 14 and 28 at 11 am and one hour after the meal. All plasma samples were analyzed for ghrelin. Normal weight women consuming the Atkins diet had lower fasting ghrelin concentrations than did women consuming the AHA diet (p=0.0141). Ghrelin concentrations in overweight women were not significantly different (p=0.8076). These results indicate a relationship of appetite-related hormones with respect to diet composition.</p