Within groups changes in cancer markers, body composition, and other outcomes will be evaluated with paired t-tests. Between group differences will be evaluated with ANOVA/ANCOVA, controlling for relevant confounders (e.g., baseline values, age). Correlation analysis will be used to test the specific hypothesis that decrease in cancer outcomes across all patients will be associated with increase in serum ketone concentrations and decreasing concentration of fasting insulin. In a pilot study of 10 cancer patients, all of whom were placed on a KD, serum ketone production was increased to a greater extent (P<0.02) in those patients who showed remission or stable disease than in those patients who showed continued disease progression (Fine et al., 2012). Further, change in ketone production was associated with change in fasting insulin concentration. Thus, sample size calculations were based on change in fasting insulin using a previous diet intervention in a population of overweight/obese women with PCOS (Gower et al. 2013). In this study, a decrease in fasting insulin of 2.7 ± 4.6 µIU/ml was observed after 8 weeks of consumption of a eucaloric reduced-carbohydrate diet. Assuming a change of 2.7 ± 4.6 (µIU/ml), a two-sided paired t-test, and a significance alpha level of 0.05, we would have over 80% power to detect a significant change in fasting insulin with 25 participants per diet group. Allowing for 30% attrition, we plan to recruit 33 participants per diet group (total n=66).