| dc.description.abstract | Background: Hormonal changes in the menstrual cycle affect energy- and macronutrient intake and appetite in women not using oral contraceptives (OC). Research has reported increased body weight in OC users compared to non-OC users, possibly due to greater energy intake. In addition, resistance training (RT) adaptations such as body composition and tendons may also differ between OC users and non-OC users. However, few studies have investigated how long-term RT affects energy- and macronutrient intake and appetite in OC users and during the menstrual cycle in non-OC users and whether there is a difference between groups. Objectives: Primarily to assess changes in energy- and macronutrient intake and appetite during pill packet periods in OC users compared to changes during menstrual cycle phases in non-OC users. Secondary, to investigate differences in energy- and macronutrient intake and appetite between the menstrual cycle phases in non-OC users and between the periods on-pill compared to no-pill in OC users. Lastly, to examine relationships between energy- and protein intake with changes in serum leptin levels, subjective appetite ratings, body composition, and muscle- and tendon adaptations in both groups after 12 weeks of RT. Methods: Healthy young women using OC and non-OC users were included in a 12-week progressive RT intervention. During the study period, both groups conducted eight dietary registration periods consisting of four days, eight appetite surveys, and four blood samples drawn to analyze for leptin and sex hormones. In addition, strength tests were performed, and body composition and ultrasound were measured at baseline and post-RT intervention. Results: The change observed in fat intake between the on-pill period (PP) and no-pill period (NPP) in the OC users (6g/day) was significantly different from the change observed between the menstrual cycle phases in the non-OC users (-5g/day) (p=0.01). Changes in energy- and other macronutrient intakes or appetite did not differ between groups (p≥0.10). In OC users, energy- and macronutrient intake was significantly higher (p≤0.03) in the PP than in the NPP. In non-OC users, no significant differences were observed between the menstrual cycle phases for any of these intakes (p≥0.08). Appetite ratings and leptin levels did not differ between the menstrual cycle phases (non-OC group) or during the OC pill packet periods (OC users). Energy- and protein intake positively correlated with changes in total and upper body lean mass (r=0.45 to 0.52) and negatively with leptin (r=-0.41 to -0.52). However, the intakes did not correlate with changes in appetite ratings, strength tests, or muscle- or tendon adaptations. Conclusion: Contrary to our hypothesis, changes observed in fat intake during pill packet periods in OC users significantly differed from those observed during the menstrual cycle phases in non-OC users. Additionally, we observed no significant changes in energy- and other macronutrient intakes or appetite between groups. Energy- and macronutrient intake changed significantly from PP to NPP in OC users but did not differ between menstrual cycle phases in non-OC users. As expected, both groups' energy- and protein intake correlated with total- and upper-body lean mass gains and leptin concentration. Further, due to less varied hormonal levels throughout a 28-day OC pill packet than during the menstrual cycle, this may affect appetite and dietary intake more in OC users than non-users. | eng |