1714-P: Higher Initial Diet Quality Predicts Shorter Weight Loss Period prior to an Involuntary Weight Loss Plateau Free

It is currently unknown what factor(s) may promote entry into a weight loss plateau. Given intensive lifestyle interventions (ILI) for weight loss include changes in diet, we evaluated how diet quality impacts characteristics of a weight loss plateau. Daily weights were obtained remotely via electronic scale from 62 adults with obesity (73% female, mean age 42±11 y and BMI 37±5 kg/m²) undergoing a 24-week ILI. Periods (≥14 d) of active weight loss or plateau were identified by threshold regression modeling. Active weight loss was defined as a per day % weight change from baseline equivalent to ≥0.5 lb loss/wk and a weight loss plateau as ±0.25lbs/wk after a period of active weight loss (in which ≥3.5% weight loss was achieved). Three unannounced self-reported ASA24 dietary recalls were obtained at baseline and 3 mo. Diet quality was assessed by the healthy eating index (HEI)-2015. 53% reached a plateau after active weight loss (27% did not achieve >3.5% weight loss, 19% re-gained directly after loss). Weight loss (i.e., plateau depth) was associated with longer time to plateau (β=–10d, P<0.01). Higher baseline diet quality (total HEI) was associated with shorter time to plateau (β=–2.6d, P=0.03), but not overall depth of plateau (β=0.1%, P=0.28). Specifically, shorter time to plateau was related to lower baseline consumption of saturated fats (β=–15d, P=0.01) and greater plateau depth was related to lower baseline consumption of added sugars (β=1.3%, P=0.04). Mean diet quality improved minimally during ILI (ΔHEI 1.9±2.2). Lower baseline HEI correlated with greater improvement in diet quality at 3 mo (β=–0.5, P<0.001, N=46), but ΔHEI did not associate with any plateau characteristics (time: β=1.1d, P=0.15; depth: β=–0.1%, P=0.16, N=25). Higher diet quality upon entry into an ILI predicted a shorter duration of weight loss prior to reaching a plateau, suggesting that individuals with healthy eating patterns may derive less sustained weight loss benefit from participation in an ILI.