Postprandial de novo lipogenesis and metabolic changes induced by a high-carbohydrate, low-fat meal in lean and overweight men.
BACKGROUND
Adjustments of carbohydrate intake and oxidation occur in both normal-weight and overweight individuals. Nevertheless, the contribution of carbohydrates to the accumulation of fat through either reduction of fat oxidation or stimulation of fat synthesis in obesity remains poorly investigated.


OBJECTIVE
The objective of this study was to assess the postprandial metabolic changes and the fractional hepatic de novo lipogenesis (DNL) induced by a high-carbohydrate, low-fat meal in lean and overweight young men.


METHODS
A high-carbohydrate, low-fat meal was administered to 6 lean and 7 overweight men after a 17.5-h fast. During the fasting and postprandial periods, energy expenditure (EE), macronutrient oxidation, diet-induced thermogenesis, and serum insulin, glucose, triacylglycerol, and fatty acids were measured. To determine DNL, [1-13C]sodium acetate was infused and the mass isotopomer distribution analysis method was applied.


RESULTS
After intake of the high-carbohydrate meal, the overweight men had hyperinsulinemia and higher fatty acid and triacylglycerol concentrations than did the lean men. The overweight group showed a greater EE, whereas there was no significant difference in carbohydrate oxidation between the groups. Nevertheless, the overweight men had a marginally higher protein oxidation and a lower lipid oxidation than did the lean men. DNL was significantly higher before and after meal intake in the overweight men and was positively associated with fasting serum glucose and insulin concentrations. Furthermore, postprandial DNL was positively correlated with body fat mass, EE, and triacylglycerol.


CONCLUSIONS
After a high-carbohydrate, low-fat meal, overweight men had a lower fat oxidation and a higher fractional hepatic fat synthesis than did lean men.
Marques-Lopes
I
I
Departments of Physiology and Nutrition and of Food Science, University of Navarra, Pamplona, Spain.
Ansorena
D
D
Astiasaran
I
I
Forga
L
L
Martínez
J A
JA
D000328:Adult; D019540:Area Under Curve; D001786:Blood Glucose / Q000032:analysis; D018752:Diet, Fat-Restricted; D004040:Dietary Carbohydrates / Q000008:administration & dosage* / Q000378:metabolism; D004041:Dietary Fats / Q000008:administration & dosage / Q000378:metabolism; D004734:Energy Metabolism; D005215:Fasting; D005227:Fatty Acids / Q000097:blood; D006801:Humans; D006946:Hyperinsulinism / Q000209:etiology*; D007328:Insulin / Q000097:blood; D008055:Lipids / Q000096:biosynthesis*; D008099:Liver / Q000378:metabolism; D008297:Male; D009765:Obesity / Q000150:complications / Q000378:metabolism*; D010084:Oxidation-Reduction; D019518:Postprandial Period; D019346:Sodium Acetate; D022722:Thermogenesis; D013997:Time Factors; D014280:Triglycerides / Q000097:blood
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D005227:Fatty Acids; D007328:Insulin; D008055:Lipids; D014280:Triglycerides; D019346:Sodium Acetate