Objectives. To investigate how age, malnutrition, and the level of plasma cortisol and phosphate in patients with Parkinson's disease (PD) at time of diagnosis are associated with body composition and handgrip strength in males and females compared to controls. Materials & Methods. This cross-sectional study includes baseline data from a cohort of newly diagnosed patients with Parkinson's disease (N = 75; M/F = 41/34) in the New Parkinsonism in Umeå study (NYPUM). Body Impedance (BIS), handgrip strength (HGS) assessments, and evaluation of risk for malnutrition (Mini Nutritional Assessment (MNA) score) and cognitive performance (Mini-Mental State Examination (MMSE)) were performed at time of PD diagnosis. Results. Low fat-free mass index (FFMI), MNA score, and a high Unified Parkinson's Disease Rating Scale (UPDRS-total and UPDRS-III) were associated with high daytime levels of P-cortisol in total PD population but not in controls. Partial correlations reveal that high fat mass percent (FM (%)) and low FFMI were associated with older age in males with PD but not females with PD. Risk of malnutrition was associated with P-cortisol in males but not in females with PD (r =-0.511, P=0.001, and n = 41 and r =-0.055, P=0.759, and n = 34, respectively). Multiple linear regressions show that an interaction between P-cortisol and P-phosphate, older age, and high UPDRS-III score were associated with HGS in total patient population and males but not females. Conclusions. Age-and disease-associated risk factors that decrease muscle mass and HGS and increase FM (%) in patients with PD differ between males and females by an association with levels of cortisol and phosphate.