Effect of Carbohydrate Overfeeding on Whole Body and Adipose Tissue Metabolism in Humans
Article first published online: 6 SEP 2012
2003 North American Association for the Study of Obesity (NAASO)
Volume 11, Issue 9, pages 1096–1103, September 2003
How to Cite
Minehira, K., Bettschart, V., Vidal, H., Vega, N., Di Vetta, V., Rey, V., Schneiter, P. and Tappy, L. (2003), Effect of Carbohydrate Overfeeding on Whole Body and Adipose Tissue Metabolism in Humans. Obesity Research, 11: 1096–1103. doi: 10.1038/oby.2003.150
- Issue published online: 6 SEP 2012
- Article first published online: 6 SEP 2012
- Received for review February 19, 2003; Accepted in final form July 15, 2003
- de novo lipogenesis;
- pentose-phosphate pathway;
- carbohydrate overfeeding
Objective: To evaluate the effect of a 4-day carbohydrate overfeeding on whole body net de novo lipogenesis and on markers of de novo lipogenesis in subcutaneous adipose tissue of healthy lean humans.
Research Methods and Procedures: Nine healthy lean volunteers (five men and four women) were studied after 4 days of either isocaloric feeding or carbohydrate overfeeding. On each occasion, they underwent a metabolic study during which their energy expenditure and net substrate oxidation rates (indirect calorimetry), and the fractional activity of the pentose-phosphate pathway in subcutaneous adipose tissue (subcutaneous microdialysis with 1, 613C2, 6, 62H2 glucose) were assessed before and after administration of glucose. Adipose tissue biopsies were obtained at the end of the experiments to monitor mRNAs of key lipogenic enzymes.
Results: Carbohydrate overfeeding increased basal and postglucose energy expenditure and net carbohydrate oxidation. Whole body net de novo lipogenesis after glucose loading was markedly increased at the expense of glycogen synthesis. Carbohydrate overfeeding also increased mRNA levels for the key lipogenic enzymes sterol regulatory element-binding protein-1c, acetyl-CoA carboxylase, and fatty acid synthase. The fractional activity of adipose tissue pentose-phosphate pathway was 17% to 22% and was not altered by carbohydrate overfeeding.
Discussion: Carbohydrate overfeeding markedly increased net de novo lipogenesis at the expense of glycogen synthesis. An increase in mRNAs coding for key lipogenic enzymes suggests that de novo lipogenesis occurred, at least in part, in adipose tissue. The pentose-phosphate pathway is active in adipose tissue of healthy humans, consistent with an active role of this tissue in de novo lipogenesis.