America and other developed countries are experiencing an obesity and type II diabetes epidemic. Type II diabetes (or adult-onset diabetes), once rarely found in young people, is becoming increasingly common in school children. Barley may help prevent insulin resistance and resulting type II diabetes and delay the onset of diabetes in individuals who are already insulin resistant. Using Syrian hamsters that became insulin resistant when fed a diet similar in fat and caloric content to the average American diet, we show that soluble fibers, including barley fiber, prevent insulin resistance and restore glucose movement into tissues. Tissues deprived of glucose in insulin-resistant hamsters turn to fat as an energy source. Fat oxidation results in the generation of free radicals and other reactive oxygen species that damage cells. Antioxidants in barley may help reduce oxidative damage.