The initial physiological responses to glucose ingestion in normal subjects are modified by a 3 d high-fat diet.
The present study was designed to investigate whether 3 d of high-fat, low-carbohydrate diet (with normal daily energy intake) affected the metabolic, cardiovascular and thermic responses to an oral glucose load (1.5 g/kg body-weight). Eight normal weight, healthy subjects (five male) consumed diets containing approximately 65% by energy of carbohydrate (C) or fat (F), each for 3 d. Before and after glucose ingestion, continuous recordings of oxygen consumption and carbon dioxide production were made using indirect calorimetry, and metabolic rate (MR) and respiratory exchange ratio (RER) were calculated. Heart rate, blood pressure and limb blood flow were also measured. There was no significant change in baseline MR following the high-fat diet, but the fasting RER was reduced. The high-fat diet modified the responses to oral glucose, with a greater increase in MR (kJ/min; C + 0.38, F +0.76), and an enhanced plasma insulin response (mU/l; C + 51.5, F + 85.0). There were no differences between the two diets with respect to the baseline blood glucose levels or the changes after glucose ingestion. Heart rate, systolic and diastolic blood pressures and blood flow responses to the glucose load were similar after the two diets. There was no plasma catecholamine response to glucose ingestion. It can be concluded that a high-fat diet alters the initial thermic response and insulin response but does not alter the other physiological responses to glucose ingestion.
Sidery
M B
MB
Department of Physiology and Pharmacology, University of Nottingham Medical School.
Gallen
I W
IW
Macdonald
I A
IA
D000328:Adult; D001786:Blood Glucose / Q000502:physiology; D002245:Carbon Dioxide / Q000502:physiology; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004041:Dietary Fats / Q000008:administration & dosage*; D005260:Female; D005947:Glucose / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D005990:Glycerol / Q000097:blood; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D006885:Hydroxybutyrates / Q000097:blood; D007328:Insulin / Q000097:blood; D007773:Lactates / Q000097:blood; D008297:Male; D009638:Norepinephrine / Q000097:blood; D010101:Oxygen Consumption / Q000502:physiology; D012881:Skin Temperature / Q000502:physiology
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D006885:Hydroxybutyrates; D007328:Insulin; D007773:Lactates; D002245:Carbon Dioxide; D005947:Glucose; D005990:Glycerol; D009638:Norepinephrine