Associazioni tra le variazioni dell'apporto proteico ed energetico riportato e stimato con le variazioni dell'insulino-resistenza, dell'emoglobina glicata e dell'IMC durante lo studio di intervento sullo stile di vita PREVIEW

Observed associations of high-protein diets with changes in insulin resistance are inconclusive. We aimed to assess associations of changes in both reported and estimated protein (P Rep ; P Est ) and energy intake (EI Rep ; EI Est ) with changes in HOMA-IR, glycated hemoglobin (HbA1c), and BMI (in kg/m 2 ), in 1822 decreasing to 833 adults (week 156) with overweight and prediabetes, during the 3-y PREVIEW (PREVention of diabetes through lifestyle intervention and population studies In Europe and around the World) study on weight-loss maintenance. Eating behavior and measurement errors (MEs) of dietary intake were assessed. Thus, observational post hoc analyses were applied. Associations of changes in EI Est , EI Rep , P Est , and P Rep with changes in HOMA-IR, HbA1c, and BMI were determined by linear mixed-model analysis in 2 arms [high-protein-low-glycemic-index (GI) diet and moderate-protein-moderate-GI diet] of the PREVIEW study. EI Est was derived from energy requirement: total energy expenditure = basal metabolic rate × physical activity level; P Est from urinary nitrogen, and urea. MEs were calculated as [(EI Est − EI Rep )/EI Est ] × 100% and [(P Rep − P Est )/P Est ] × 100%. Eating behavior was determined using the Three Factor Eating Questionnaire, examining cognitive dietary restraint, disinhibition, and hunger. Increases in P Est and P Rep and decreases in EI Est and EI Rep were associated with decreases in BMI, but not independently with decreases in HOMA-IR. Increases in P Est and P Rep were associated with decreases in HbA1c. P Rep and EI Rep showed larger changes and stronger associations than P Est and EI Est . Mean ± SD MEs of EI Rep and P Rep were 38% ± 9% and 14% ± 4%, respectively; ME changes in EI Rep and En% P Rep were positively associated with changes in BMI and cognitive dietary restraint and inversely with disinhibition and hunger. During weight-loss maintenance in adults with prediabetes, increase in protein intake and decrease in energy intake were not associated with decrease in HOMA-IR beyond associations with decrease in BMI. Increases in P Est and P Rep were associated with decrease in HbA1c. This trial was registered at clinicaltrials.gov as NCT01777893 .