During the last decades, nutritional fat intake has continuously inflated in parallel with an enormous rise in the prevalence of obesity and type-2 diabetes in adults but increasingly also in adolescents and even children. Augmented fat intake is associated with an increased mass of adipose tissue which releases free fatty acids (FFA) but also hormones and cytokines such as leptin, adiponectin, resistin, tumor necrosis factor-a and interleukin-6. In particular, FFA decrease insulin-mediated glucose transport/ phosphorylation in skeletal muscle and impair suppression of glucose production by the liver, indicating insulin resistance. In addition, ectopic lipid storage in both liver and skeletal muscle has recently been related to reduced insulin sensitivity. In conclusion, increased fat intake and expanded body fat are now held responsible for increased FFA availability and hormonal changes which may lead to insulin resistance and type- 2 diabetes.