RESUMO
BACKGROUND: In homeothermic animals, approximately 50% of daily energy expenditure (EE) is spent to maintain a consistent core body temperature (CBT). In humans, little is known about CBT responses to feeding and overfeeding and their relationship to diet-related changes in EE. OBJECTIVE: To study the effects of feeding and overfeeding on CBT and its association with diet-induced thermogenesis (DIT). DESIGN: Fifty-three healthy men with normal glucose regulation and a wide range of body composition (mean⯱â¯SD, body fat: 25⯱â¯8%, range: 7-43%) had 24-h EE assessed during fasting in a whole-room indirect calorimeter with concomitant CBT measurement by ingestible capsules and 24-h urinary collection for catecholamine measurements. Changes in 24-h EE (DIT) and CBT compared to fasting were assessed during three normal-protein (20%) diets using a cross-over design: one eucaloric diet (EBL, 50% carbohydrate, nâ¯=â¯37) and two overfeeding diets with 200% energy requirements: a high-fat (FNP, 60% fat, nâ¯=â¯25) and a high-carbohydrate (CNP; 75% carbohydrate, nâ¯=â¯24) diet. RESULTS: The average 24-h CBT (avgCBT) during fasting was 36.81⯱â¯0.14⯰C (inter-individual CVâ¯=â¯0.4%) and positively correlated with 24-h urinary epinephrine (râ¯=â¯0.61, pâ¯<â¯0.001), but not with body composition measures (pâ¯>â¯0.05). AvgCBT increased during EBL (Δâ¯=â¯0.06⯱â¯0.11⯰C, pâ¯=â¯0.002), FNP (Δâ¯=â¯0.13⯱â¯0.14⯰C, pâ¯<â¯0.001), and CNP (Δâ¯=â¯0.19⯱â¯0.13⯰C, pâ¯<â¯0.001) and associated with increased DIT during EBL (râ¯=â¯0.43, pâ¯=â¯0.01, ßâ¯=â¯31â¯kcal/day/0.1⯰C) and FNP (râ¯=â¯0.60, pâ¯=â¯0.002, ßâ¯=â¯43â¯kcal/day/0.1⯰C), but not CNP (pâ¯=â¯0.47). A ceiling effect for the increase in CBT, but not in DIT, was observed during feeding and, particularly, overfeeding. CONCLUSIONS: CBT increases with feeding and is moderately associated with DIT to a different degree depending on the macronutrient composition of the overfeeding diet. There is a ceiling effect such that individuals with a higher CBT during fasting have limited capacity to increase CBT with feeding. Because of body thermoregulatory mechanisms that maintain a constant CBT, these results indicate that CBT has a limited role in the inter-individual variability in DIT.
Assuntos
Temperatura Corporal , Ingestão de Alimentos/fisiologia , Metabolismo Energético , Epinefrina/urina , Voluntários Saudáveis , Termogênese , Adulto , Dieta , Jejum , Humanos , MasculinoRESUMO
OBJECTIVE: This study sought to understand how the dietary source of carbohydrates, either high-fructose corn syrup (HFCS) or complex carbohydrates, affects energy expenditure (EE) measures, appetitive sensations, and hormones during 24 hours of overfeeding. METHODS: Seventeen healthy participants with normal glucose regulation had 24-hour EE measures and fasting blood and 24-hour urine collection during four different 1-day diets, including an energy-balanced diet, fasting, and two 75% carbohydrate diets (5% fat) given at 200% of energy requirements with either HFCS or whole-wheat foods as the carbohydrate source. In eight volunteers, hunger was assessed with visual analog scales the morning after the diets. RESULTS: Compared with energy balance, 24-hour EE increased 12.8% ± 6.9% with carbohydrate overfeeding (P < 0.0001). No differences in 24-hour EE or macronutrient utilization were observed between the two high-carbohydrate diets; however, sleeping metabolic rate was higher after the HFCS diet (Δ = 35 ± 48 kcal [146 ± 200 kJ]; P = 0.01). Insulin, ghrelin, and triglycerides increased the morning after both overfeeding diets. Urinary cortisol concentrations (82.8 ± 35.9 vs. 107.6 ± 46.9 nmol/24 h; P = 0.01) and morning-after hunger scores (Δ = 2.4 ± 2.0 cm; P = 0.01) were higher with HFCS overfeeding. CONCLUSIONS: The dietary carbohydrate source while overeating did not affect 24-hour EE, but HFCS overconsumption may predispose individuals to further overeating due to increased glucocorticoid release and increased hunger the following morning.