Background Characterization of mild cognitive impairment (MCI) for clinical and research purposes involves identification of biological and neuropsychological markers in order to predict possible progression to dementia. The main aim of this work was to analyze the correlation of anthropometric measurements and plasmatic levels of leptin, testosterone and estrogens with cognitive, CSF and MRI regional atrophy markers in a sample of MCI participants. Methods Eighty‐one patients from the Compostela Aging Study diagnosed as MCI according to the Petersen criteria (Petersen, 2004; Albert et al., 2011) underwent neuropsychological assessment (CAMCOG‐R memory, CVLT short and long delayed free recall, subjective memory complains), CSF (Aβ42, t‐Tau and p‐Tau) and plasmatic analyses as well as an MRI study (parahippocampal and entorhinal cortex thickness measurements) (Table 1). Spearman’s correlation was used to evaluate the relationship between anthropometric measurements and blood test results with memory scores, CSF and MRI regional atrophy markers. Results Episodic memory scores correlated with CSF measurements (Aβ42, t‐Tau, p‐Tau) and parahippocampal and entorhinal cortical thickness (right and left) (Table 2). BMI, suprailiac, pectoral and subscapular skinfolds, circumference of waist, hip, arm and calf were negatively correlated with t‐Tau and p‐Tau levels. BMI, triccipital, thigh and pectoral skin folds as well as calf circumference were positively correlated with parahippocampal and entorhinal cortical thickness. Suprailiac, triccipital and thigh skin folds were positively correlated with episodic memory scores. Leptin plasma levels showed a negative correlation with CSF biomarkers (t‐Tau and p‐Tau) and a positive correlation with parahippocampal cortex thickness. Testosterone and estradiol levels showed a negative correlation with scores on memory tests and enthorhinal cortical thickness. Conclusions Our findings suggest that body composition is associated with episodic memory function, CSF biomarkers and cortical atrophy in patients with MCI. Leptin levels and sexual hormones may play a role in this association. These results point to a role of fat tissue and its regulating mechanisms in AD pathology and progression from MCI to dementia.