Variations In Copeptin And Cortisol Do Not Influence Ad Libitum Breakfast Consumption

PURPOSE: Chronic elevations in cortisol are associated with preference for foods higher in fat and sugar content, which may increase energy intake (EI). Underhydration has been associated with greater risk for obesity and elevated resting cortisol concentrations. However, the influence of underhydration on cortisol responses and subsequent EI remains largely unknown. This study explored the effects of variations in copeptin (a marker of underhydration) and cortisol on energy and macronutrient intake during an ad-libitum breakfast. METHODS: Ten healthy adults (1 female; Age, 25 ± 4 y; Height, 177.9 ± 7.4 cm; body mass, 75.8 ± 13.8 kg; body fat, 13.5 ± 7.1%) received an ad-libitum breakfast with a variety of food items on two separate occasions the morning after sleeping in temperate (TTEMP, 25 °C, 30% RH) and hot (THOT, 30 °C, 30% RH) environmental conditions, in a randomized order. Blood and saliva were collected immediately prior to the ad-libitum breakfast (45 minutes post-awakening), analyzed for serum copeptin (COP) and salivary cortisol (CORT), respectively. Separate random-intercept linear mixed-effects models assessed the effects of individual mean-centered COP and CORT concentrations on ad-libitum EI and macronutrient intake at breakfast, controlling for condition. RESULTS: CORT concentration (p = 0.84), COP concentration (p = 0.84), EI (p = 0.25), and protein (p = 0.62), fat (p = 0.53), and carbohydrate (p = 0.239) consumption did not differ by condition. Within-person changes in copeptin or cortisol were not associated with EI (kcals, βCOP = 20.38, [95%CI; -35.93, 76.79], p = 0.463], βCORT = -14.02, [-33.68, 5.64], p = 0.17) or macronutrient intake; (protein, βCOP = -0.15 [-2.74, 2.45], p = 0.91, βCORT = -0.37, [-1.28, 0.53], p = 0.41; carbohydrates, βCOP = 4.90 [-4.25, 14.0] p = 0.29, βCORT = -1.34, [-4.53, 1.86], p = 0.398; fat, βCOP = 0.24 [-3.70, 4.19], p = 0.90, βCORT = -0.78, [-2.16, 0.59], p = 0.26) when controlling for condition. CONCLUSIONS: Variations in morning CORT and COP did not influence ad-libitum EI or macronutrient intake at breakfast. These preliminary findings suggest that variations in these markers may not influence EI, but greater perturbances to these hormones and the effect on eating behaviors warrants further consideration. Funding Information: This study was funded in part by Bedgear, LLC.