Abstract
BACKGROUND: Caloric restriction prolongs lifespan in model organisms and improves metrics of aging-related diseases in humans, but daily compliance is challenging. Intermittent fasting improves metrics of lipid and glucose metabolism in the setting of weight loss but whether these metrics are improved independent of weight loss is not known. METHODS: We seek to address this gap with IFAST, a single-center, three-arm, prospective, randomized, controlled clinical trial. Eligible study participants are adults with no chronic medical conditions beyond prediabetes or overweight but who are at high risk for type 2 diabetes mellitus (T2D), defined as having a history of gestational diabetes or a first-degree relative with T2D. Participants will be randomized in a 1:2:2 schema to either a control group, a fasting group, or a fasting/weight maintenance group. The fasting groups will complete a 24-h fast one day per week for 12 weeks. The key mechanistic endpoint is change in triglyceride composition (defined by carbon content and degree of saturation) as measured by longitudinal metabolomics. The key safety endpoint is percent change from baseline in bone volume fraction (BV/TV; high-resolution peripheral quantitative CT) at the radius in the fasting group. Secondary endpoints include measures of insulin sensitivity (hyperinsulinemic-euglycemic clamp), clinical lipid profiling, systemic inflammation markers, hunger assessment, bone density, and bone microarchitecture with high-resolution peripheral quantitative CT. CONCLUSION: IFAST will investigate intrinsic metabolic benefits of intermittent fasting beyond weight loss. TRIAL REGISTRATION: ClinicalTrials.gov ID NCT05722873.