The number of patients with metabolic syndrome, type 2 diabetes mellitus, and obesity increases all over the world; the prevalence of these conditions in developed countries amounts to 20-30 per 1,000 adult population. Most studies demonstrate their direct relation to non-alcoholic fatty infiltration of the liver. MRI is the only non-invasive method allowing to quantitatively determine the degree of fatty infiltration of the liver with high sensitivity and specificity comparable with those attainable by morphological studies. Proton magnetic resonance spectroscopy is an effective non-invasive diagnostic method for dynamic and quantitative evaluation of fat content in the liver undergoing non-alcoholic fatty infiltration. Specifically, its application to estimate the efficacy of a lipid-reducing diet and therapy revealed normalization of lipid metabolism in 57% of the patients within 6 months after the onset of the treatment (the lipid level decreased two-fold in 28% of the patients).