Despite many different trials, no effective dietotherapy exists for curing enormous weight loss caused by malignant diseases yet. The present study was aimed at determining in an animal model, weather some natural products might be included in the dietotherapy of cancerous patients with cachexia. Tumour was transplanted into Fischer 344 rats drinking either seabuckthorn extract, green tea, deuterium depleted water, trace elements preparation, fruits’ extract or multivitamin solution. Weight loss, tumour growth and expression of Ha-ras gene were determined. All the investigated natural products have significantly decreased tumour growth, and trace elements preparation has significantly decreased weight loss. Green tea, seabuckthorn extract and deuterium depleted water have notably diminished Ha-ras gene expression. Our results suggest that these natural products may be useful in inhibiting tumour growth, and some of them may be applied in the dietotherapy of cancer-related weight loss.