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.