Influence of Energy Balance and Glycemic Index on Metabolic Endotoxemia in Healthy Men

Abstract

Objective: Overfeeding with a high-fat and/or high-carbohydrate (CHO) diet is known to increase plasma concentrations of endotoxin (lipopolysaccharide [LPS]) that may lead to metabolic disturbances like insulin resistance. The impact of CHO quality (i.e., the glycemic index [GI]) independent of fat intake on metabolic endotoxemia remains unclear. In the present study, the effects of changes in energy balance and GI on plasma endotoxin were studied.

Methods: Fifteen healthy young men overconsumed diets containing 65% CHO and 20% fat for 1 week (OF; +50% of energy requirement) followed by 3 weeks of caloric restriction (CR; −50% of energy requirement) and were then randomized to 2 weeks hypercaloric refeeding (RF, +50% of energy requirement) with either a low- or high-GI (40 vs 74) diet.

Results: During OF, subjects gained 1.9 ± 0.7 kg body weight (+0.6 ± 0.8% fat mass) followed by a weight loss of 6.1 ± 0.8 kg (−2.0 ± 0.6% fat mass) and weight regain of 4.0 ± 0.6 kg (0.9 ± 0.8% fat mass). Fasting insulin and homeostasis model assessment–insulin resistance (HOMA_IR) increased with OF and RF and decreased with CR, Matsuda_ISI decreased by 37% after RF (all p < 0.05). Endotoxin significantly increased by 30.8% with OF and by 24.7% with RF (both p < 0.05), whereas CR normalized endotoxin levels. No difference in endotoxin levels was observed between refeeding a hypercaloric high- or low-GI diet. Changes in endotoxin levels with RF were not related to changes in insulin sensitivity.

Conclusion: A hypercaloric diet (OF and RF) increased plasma endotoxin irrespective of GI, whereas a negative energy balance did not reduce endotoxemia. Impaired insulin sensitivity with hypercaloric refeeding on a high-GI diet was not explained by metabolic endotoxemia.

Key words:

• endotoxin
• glycemic index
• weight cycle
• energy balance
• insulin sensitivity

ACKNOWLEDGMENTS

We thank all of the subjects for their participation in the study. The authors declare no conflict of interest.

Funding

The present study was supported by a grant from the German Ministry of Education and Research (BMBF 0315681) and the German Research Foundation (DFG Bo 3296/1-1).

AUTHOR CONTRIBUTIONS

M.J.M. and A.B.-W. designed the research; M.L. and A.B.-W. conducted the research; N.B., A.B.-W., M.J.M., and I.B. discussed the data; A.J.E. analyzed the data; N.B. and A.B.-W. wrote the article; N.B. and A.B.-W. had primary responsibility for the final content. All authors read and approved the final article.