Can a Higher Protein/Low Glycemic Index vs. a Conventional Diet Attenuate Changes in Appetite and Gut Hormones Following Weight Loss? A 3-Year PREVIEW Sub-study

Abstract

Background: Previous research showed that weight-reducing diets increase appetite sensations and/or circulating ghrelin concentrations for up to 36 months, with transient or enduring perturbations in circulating concentrations of the satiety hormone peptide YY. Objective: This study assessed whether a diet that is higher in protein and low in glycemic index (GI) may attenuate these changes. Methods: 136 adults with pre-diabetes and a body mass index of ≥25 kg/m² underwent a 2-month weight-reducing total meal replacement diet. Participants who lost ≥8% body weight were randomized to one of two 34-month weight-maintenance diets: a higher-protein and moderate-carbohydrate (CHO) diet with low GI, or a moderate-protein and higher-CHO diet with moderate GI. Both arms involved recommendations to increase physical activity. Fasting plasma concentrations of total ghrelin and total peptide YY, and appetite sensations, were measured at 0 months (pre-weight loss), at 2 months (immediately post-weight loss), and at 6, 12, 24, and 36 months. Results: There was a decrease in plasma peptide YY concentrations and an increase in ghrelin after the 2-month weight-reducing diet, and these values approached pre-weight-loss values by 6 and 24 months, respectively (P = 0.32 and P = 0.08, respectively, vs. 0 months). However, there were no differences between the two weight-maintenance diets. Subjective appetite sensations were not affected by the weight-reducing diet nor the weight-maintenance diets. While participants regained an average of ~50% of the weight they had lost by 36 months, the changes in ghrelin and peptide YY during the weight-reducing phase did not correlate with weight regain. Conclusion: A higher-protein, low-GI diet for weight maintenance does not attenuate changes in ghrelin or peptide YY compared with a moderate-protein, moderate-GI diet. Clinical Trial Registry: ClinicalTrials.gov registry ID NCT01777893 (PREVIEW) and ID NCT02030249 (Sub-study).

Keywords: appetite; ghrelin; gut hormones; peptide YY; weight maintenance.

Figure 1

Trial flow diagram. The trial involved a 2-month weight-reducing diet consisting of a total meal replacement diet with a prescribed daily energy intake of 3,400 kJ (800 kcal). As per the registered trial design, participants who lost 8% or more of their initial body weight proceeded to a 34-month weight-maintenance diet involving either a diet with a higher protein (25% of energy) and moderate carbohydrate content (45% of energy) with a low glycemic index (≤50) (HP/LGI) vs. a diet with a moderate protein (15% of energy) and higher carbohydrate content (55% of energy) with a moderate GI (≥56) (MP/MGI).

Figure 2

Weight (A) and fasting plasma gut hormone concentrations [Ghrelin (B) and Peptide YY (C)] before, during, and after the weight-reducing (gray shaded bar) and weight-maintenance diets of the PREVIEW sub-study [either a higher protein/low GI (HP/LGI) or a moderate-protein/moderate-GI (MP/MGI) weight-maintenance diet]. Results of a constrained linear mixed model (2–36 months) are shown as estimated marginal means (i.e., means adjusted for age, sex, exercise group, and the value at 0 months) ± 95% CI. There were no statistically significant differences between the weight-maintenance diets at any time point (P-values for the interaction of diet*time are shown on each panel). Ghrelin and peptide YY were log-transformed in the analyses.