PROP Nontaster Women Lose More Weight Following a Low-Carbohydrate Versus a Low-Fat Diet in a Randomized Controlled Trial

Objective: Taste blindness to 6-n-propylthiouracil (PROP) associates with increased fat preference and intake. No studies have matched a diet to a woman's PROP phenotype to improve weight loss. This study investigated (1) whether PROP nontaster (NT) women would lose more weight following a low-carbohydrate (LC) diet than a low-fat (LF) diet, and (2) whether PROP supertaster (ST) women would lose more weight following a LF diet than a LC diet. Methods: One hundred seven women (BMI = 34.8 ± 0.5 kg/m²), classified as PROP NTs (n = 47) and STs (n = 60), were randomized to a LC or LF diet within a 6-month lifestyle intervention. Assessments included 4-day dietary recalls and biobehavioral and psychosocial questionnaires. Results: At 6 months, NTs lost more weight following the LC than the LF diet (−8.5 ± 0.5 kg vs. −6.6 ± 0.5 kg, P = 0.008); there was no difference between STs following either diet (−8.8 ± 0.4 vs. −8.9 ± 0.5, P = 0.35). Dietary self-reports were unrelated to weight loss, and prescription of a LC diet associated with greater self-efficacy. Conclusions: NT women lost more weight following the LC diet compared to the LF diet. Screening for PROP phenotype may help personalize diet therapy for NT women to optimize their short-term weight loss.