The impact of weight loss on the 24-h profile of circulating peptide YY and its association with 24-h ghrelin in normal weight premenopausal women

Peptide YY (PYY) and ghrelin exhibit a reciprocal association and antagonistic physiological effects in the peripheral circulation. Research has yet to clarify the effect of weight loss on the 24 h profile of PYY or its association to 24 h ghrelin. We sought to determine if diet-and exercise-induced weight loss affects the 24 h profile of PYY and its association with 24 h ghrelin in normal weight, premenopausal women. Participants (n = 13) were assessed at baseline (BL) and after a 3-month diet and exercise intervention (post). Blood samples obtained q10 min for 24 h were assayed for total PYY and total ghrelin q60 min from 0800 to 1000 h and 2000 to 0800 h and q20 min from 1000 to 2000 h. The ghrelin/PYY ratio was used as an index of hormonal exposure. Statistical analyses included paired t-tests and linear mixed effects modeling. Body weight (-1.85 +/- 0.67 kg; p = 0.02), and body fat (-2.53 +/- 0.83%; p = 0.01) decreased from BL to post. Ghrelin AUC (5252 +/- 2177 pg/ml/24 h; p = 0.03), 24 h mean (216 +/- 90 pg/ml; p = 0.03) and peak (300 +/- 134 pg/ml; p = 0.047) increased from BL to post. No change occurred in PYY AUC (88.2 +/- 163.7 pg/ml; p = 0.60), 24 h mean (4.8 +/- 6.9 pg/ml; p = 0.50) or peak (3.6 +/- 6.4 pg/ml; p = 0.58). The 24 h association between PYY and ghrelin at baseline (p = 0.04) was weakened at post (p = 0.14); however, the ghrelin/PYY lunch ratio increased (p = 0.01) indicating the potential for ghrelin predominance over PYY in the circulation. PYY and ghrelin are reciprocally associated during a period of weight stability, but not following weight loss. An "uncoupling" may have occurred, particularly at lunch, due to factors that modulate ghrelin in response to weight loss. (C) 2013 Elsevier Inc. All rights reserved.