An object of the present invention is to provide a diet therapy for suppressing tumor growth of refractory cancer, for treating refractory cancer, or for enhancing the effect of another cancer treatment. The present invention provides a saccharide restricted high fat composition for use in suppressing tumor growth of refractory cancer, treating refractory cancer and/or enhancing the effect of another cancer treatment. The composition of the present invention can comprise about 55% by mass or more of fat based on the total solid content contained in the composition. The composition of the present invention can also comprise about 0% by mass to about 15% by mass of saccharide based on the total solid content contained in the composition. The composition of the present invention can also comprise a medium chain fatty acid oil as fat.
