Background: The well-known metabolic effects of glucocorticoids have stimulated interest about the hypothetical role in changing of hypothalamic-pituitary-adrenal (HPA) axis in obesity. Complex and bidirectional relationships between HPA axis and food intake have been also reported to occur as part of the brain-gut axis. In particular, the increase in cortisol release after high-protein meals has been considered as a neuroendocrine response to food allergens, and is likely mediated via vagal afferent activity. Salivary cortisol, which represents the amount of biologically active free circulating cortisol, is a simple and reliable measure to assess HPA function in outpatient settings. While there is evidence of an increase in salivary cortisol after a single high-protein meal, there are no data on salivary cortisol levels following a prolonged high-protein intake. Objective: the aim of this study was to evaluate in a group of female obese subjects the influence of a moderately hypocaloric high-protein diet on salivary cortisol and body composition. Materials and methods: Thirty consecutive female obese subjects (age 35.813.9 yrs; BMI 34.85.9 kg/m2; waist circumference 11216 cm) received a moderately hypocaloric diet with high-protein intake (25% energy intake) for 30 days. The body composition and basal metabolism were evaluated by Body Impedance Assessment (BIA) (Akern Bioresearch, Firenze) and Impedance Vector Analysis using the BIVA software (Piccoli A, Pastori G (2002). The estimation of dietary intake was assessed by Winfood (Winfood light 1.0, 2002, Rome, Italy). Salivary cortisol levels were analyzed by ELISA method (DRG Diagnostics). Results: after high-protein diet, salivary cortisol levels (Δ 3.2 ± 3.3 ng/ml; p<0.001), fat free mass (FFM: Δ 2.2 ± 4.1 kg; p=0.042), and resistance/height (Δ 9.0 ± 21.7 Ω; p=0.005) increased compared with baseline, while body weight (Δ -3.5 ± 1.6 kg; p<0.001), waist circumference (Δ -2.6 ± 1.3 cm; p<0.001), fat mass (FM: Δ -1.9 ± 8.5 kg; p=0.005), and total body water (Δ -1.3 ± 2.9 l; p=0.044) decreased. Conclusions: Apart from the effect of single high-protein meal, salivary cortisol levels increased also following a 30-day moderately hypocaloric high-protein diet, associated to a decrease in FM and an increase in FFM. This association was likely related to the combined influence of mild hypocaloric diet and insulinotropic effects of the high-protein intake on preventing the adverse effects of cortisol on body composition. Our data further supported the role of the bidirectional relationships between diet composition and HPA axis in the pathogenesis of obesity and confirmed the relevance of defining the optimal dietary treatment strategies in different obesity phenotypes.
Influence of Nutrition on the HPA axis and body composition: effect of 30-day moderately hypocaloric high-protein diet in obese female subjects
Barrea L;
2011-01-01
Abstract
Background: The well-known metabolic effects of glucocorticoids have stimulated interest about the hypothetical role in changing of hypothalamic-pituitary-adrenal (HPA) axis in obesity. Complex and bidirectional relationships between HPA axis and food intake have been also reported to occur as part of the brain-gut axis. In particular, the increase in cortisol release after high-protein meals has been considered as a neuroendocrine response to food allergens, and is likely mediated via vagal afferent activity. Salivary cortisol, which represents the amount of biologically active free circulating cortisol, is a simple and reliable measure to assess HPA function in outpatient settings. While there is evidence of an increase in salivary cortisol after a single high-protein meal, there are no data on salivary cortisol levels following a prolonged high-protein intake. Objective: the aim of this study was to evaluate in a group of female obese subjects the influence of a moderately hypocaloric high-protein diet on salivary cortisol and body composition. Materials and methods: Thirty consecutive female obese subjects (age 35.813.9 yrs; BMI 34.85.9 kg/m2; waist circumference 11216 cm) received a moderately hypocaloric diet with high-protein intake (25% energy intake) for 30 days. The body composition and basal metabolism were evaluated by Body Impedance Assessment (BIA) (Akern Bioresearch, Firenze) and Impedance Vector Analysis using the BIVA software (Piccoli A, Pastori G (2002). The estimation of dietary intake was assessed by Winfood (Winfood light 1.0, 2002, Rome, Italy). Salivary cortisol levels were analyzed by ELISA method (DRG Diagnostics). Results: after high-protein diet, salivary cortisol levels (Δ 3.2 ± 3.3 ng/ml; p<0.001), fat free mass (FFM: Δ 2.2 ± 4.1 kg; p=0.042), and resistance/height (Δ 9.0 ± 21.7 Ω; p=0.005) increased compared with baseline, while body weight (Δ -3.5 ± 1.6 kg; p<0.001), waist circumference (Δ -2.6 ± 1.3 cm; p<0.001), fat mass (FM: Δ -1.9 ± 8.5 kg; p=0.005), and total body water (Δ -1.3 ± 2.9 l; p=0.044) decreased. Conclusions: Apart from the effect of single high-protein meal, salivary cortisol levels increased also following a 30-day moderately hypocaloric high-protein diet, associated to a decrease in FM and an increase in FFM. This association was likely related to the combined influence of mild hypocaloric diet and insulinotropic effects of the high-protein intake on preventing the adverse effects of cortisol on body composition. Our data further supported the role of the bidirectional relationships between diet composition and HPA axis in the pathogenesis of obesity and confirmed the relevance of defining the optimal dietary treatment strategies in different obesity phenotypes.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
