Importance Altough disease-modifying factors such as malnutrition and diet have been associated with Alzheimer’s disease (AD), little is known about the effects of pharmacological therapies on the nutritional status of AD patients. Objective To evaluate the nutritional status, prealbumin, and albumin serum levels and several anthropometric measurements in patients with probable moderate-stage AD, with and without rivastigmine drug treatment. Study design A cross-sectional study. Setting and participants 34 patients were included, 17 with rivastigmine treatment and 17 without pharmacological treatment, over 60 years of both sexes. Measurements The nutritional status was evaluated using the Mini Nutritional Assessment (MNA). Albumin and prealbumin (transthyretin) levels and anthropometric evaluation were assessed using standard methods. Results A polarity of malnutrition was detected in the untreated group. According to the MNA survey, the risk of malnutrition is higher without rivastigmine treatment (p = 0.0001). There are a less loss of appetite, less psychological stress, greater mobility and independence in those patients receiving rivastigmine (p = 0.003, 0.008, 0.016 and 0.018, respectively). The body mass index does not show a statistical difference, however, categorizing it for older adults, this index was improved in those receiving rivastigmine (p = 0.016). The serum levels of albumin and prealbumin showed no significant statistical difference between the groups. Conclusions Rivastigmine treatment shows a protective effect on malnutrition in patients with moderate-stage AD.