Study design
SECONDARY
Our post hoc secondary analysis utilized data from the DIETFITS study, of which detailed methods have previously been published [The DIETFITS trial was overseen by the Stanford University Institutional Review Board and was registered with After baseline data collection, participants’ random assignment to the HLC or HLF diet was revealed at their first intervention class. The intervention consisted of 22 sessions of class-based instruction conducted by registered dietitian nutritionists (RDNs) held over 12 mo within diet groups. Classes were conducted weekly for 8 wk, then every 2 wk for 2 mo, then every 3 wk until Month 6, and then monthly through Month 12. Dietary goals included reducing net carbohydrate or fat intake to 20 g or less for 8 wk, then slowly increasing over time until each participant found the level of intake they could sustain indefinitely, reducing intake of highly processed foods and added sugars, and maximizing intake of vegetables and other whole foods. There was no explicit energy restriction. Dietary data collection was conducted via 3 unannounced, 24-h dietary recalls using a standardized, multiple-pass approach [For the current analysis, participants who provided complete 24-h dietary recall data at baseline and 12 mo were included (total This study was a post hoc secondary analysis. The predefined primary outcome was 12-mo change in BMI. Predefined secondary outcomes included 12-mo change in the following cardiometabolic measures: systolic blood pressure (SBP), diastolic blood pressure (DBP), fasting plasma glucose, insulin, triglycerides, HDL cholesterol, and LDL cholesterol concentrations. The reference subgroup was LQ/LA. All clinical measurements (body weight, height, blood pressure, and a fasting blood draw, which would be analyzed for insulin, glucose, lipids, and triglycerides concentrations) were collected by the Stanford Clinical Translational Research Unit at each data collection time point [