title: Metabolic responses to nocturnal eating in men are affected by sources of dietary energy.
abstract: Because night work is becoming more prevalent, we studied whether feeding at different times of a 24-h period would elicit different metabolic responses and whether dietary macronutrient composition would affect these responses. Seven men (26-43 y, 19.9-26.6 kg/m(2)) consumed two isocaloric diets, in a crossover design. The diets were a high carbohydrate (HC) diet [65 energy % (E%) carbohydrates, 20E% fat] and a high fat (HF) diet (40E% carbohydrates, 45E% fat). After a 6-d diet-adjustment period, the men were kept awake for 24 h and the food (continuation of respective diet) was provided as six isocaloric meals (i.e., every 4 h). Energy and substrate turnover, heart rate, mean arterial pressure (MAP), blood glucose, triacylglycerol (TAG), nonesterified fatty acid (NEFA) and glycerol were measured throughout the 24-h period. Significantly higher energy expenditure and NEFA concentration, and lower blood glucose and TAG concentrations were observed when the men consumed the HF diet than when they consumed the HC diet. Significant circadian patterns were seen in body and skin temperature (nadir, 0400-0500 h). When the men consumed the HF diet, significant circadian patterns were seen in fat oxidation (nadir, 0800-1200 h; plateau, 1200-0800 h), heat release (nadir, 0800-1200 h; plateau, 1600-0800 h), heart rate (nadir, 0000 h), blood glucose (nadir, 0800-1200 h; peak, 0000-0400 h), NEFA (nadir, 0800-1200 h; peak, 1200-2000 h) and TAG (nadir, 0800-1200 h; peak, 0400-0800 h) concentrations. Energy expenditure, carbohydrate oxidation, MAP and glycerol concentration did not display circadian patterns. Unequal variances eradicated most circadian effects in the HC-diet data. The increased TAG concentration in response to feeding at 0400 h might be involved in the higher TAG concentrations seen in shift workers. Distinct macronutrient/circadian-dependent postprandial responses were seen in most studied variables.
authors.affiliation: Nutrition Unit, Department of Medical Sciences, Uppsala University Hospital, Sweden. Ulf.Holmback@medsci.uu.se
authors.forename: Ulf
authors.initials: U
authors.lastname: Holmbäck
authors.forename: Anders
authors.initials: A
authors.lastname: Forslund
authors.forename: Jeanette
authors.initials: J
authors.lastname: Forslund
authors.forename: Leif
authors.initials: L
authors.lastname: Hambraeus
authors.forename: Maria
authors.initials: M
authors.lastname: Lennernäs
authors.forename: Arne
authors.initials: A
authors.lastname: Lowden
authors.forename: Mats
authors.initials: M
authors.lastname: Stridsberg
authors.forename: Torbjörn
authors.initials: T
authors.lastname: Akerstedt
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D001831:Body Temperature; D002940:Circadian Rhythm; D018592:Cross-Over Studies; D004032:Diet; D004041:Dietary Fats / Q000008:administration & dosage / Q000494:pharmacology; D004435:Eating / Q000502:physiology*; D004734:Energy Metabolism; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005990:Glycerol / Q000097:blood; D006801:Humans; D050356:Lipid Metabolism; D008297:Male; D009994:Osmolar Concentration; D010084:Oxidation-Reduction; D012881:Skin Temperature; D013997:Time Factors; D014280:Triglycerides / Q000097:blood; D014940:Work Schedule Tolerance
chemical_list: D001786:Blood Glucose; D004041:Dietary Fats; D005230:Fatty Acids, Nonesterified; D014280:Triglycerides; D005990:Glycerol