A Personalized Diet Study to Reduce Glycemic Exposure

Inclusion Criteria: * Healthy overweight or obese prediabetic (HbA1c \<8.0%) * BMI ≥27 kg/m2 * Oral medications with metformin, sulfonylureas, DPP4 inhibitors * Posses smartphone or use study loaner smartphone Exclusion Criteria: * unable or unwilling to provide informed consent * unable to participate meaningfully in an intervention that involves self-monitoring using software available in English (e.g., due to uncorrected sight impairment, illiterate, non-English-speaking, dementia) * unwilling to accept randomization assignment * women who pregnant, or plan to become pregnant in the next 13 months, or who become pregnant during the study * institutionalized (e.g., in a nursing home or personal care facility, or those who are incarcerated and have limited control over diet) * unwilling to delay bariatric surgery for the next 12 months * diagnosed with heart disease, kidney disease, or retinopathy, (to rule-out those with long-standing T2D) * chronically active inflammatory or neoplastic disease in the past 3 years * diagnosed with a chronic gastrointestinal disorder (e.g. inflammatory bowel disease or celiac disease) * diagnosed with active infection requiring antibiotics in the last 3 months or who develop an active infection requiring antibiotics during the study * taking medications containing acetaminophen and are unwilling or unable to discontinue its use during the study (acetaminophen affects the accuracy of the continuous glucose monitoring \[CGM\] device) * taking chronic immunosuppressive medications or used them in the 3 months prior to participation, or during the study * managing glycemia with insulin, GLP-I agonists (exenatide, liraglutide, lixisenatide, albiglutide, dulaglutide), insulin secretagogues (Glimepiride, Glipizide, Glyburide, Repaglinide, Nateglinide), or SGLT2 inhibitors (canagliflozin, dapagliflozin, empagliflozin, empagliflozin/metformin, dapagliflozin/metformin) * prescribed medications expected to result in weight loss such as Orlistat, Naltrexone, Bupropion, Lorcaserin, Phentermine, Topiramate, or Liraglutide, and who are unwilling to delay treatment with these medications for the next 12 months * +/- 5% weight change within last month at screening * a eGFR \<60 mL/min/1.73m2 * younger than 18 or older than 80 years old.