Plasma fatty acyl-carnitines during 8 weeks of overfeeding: relation to diet energy expenditure and body composition: the PROOF study - PubMed (original) (raw)

Randomized Controlled Trial

Plasma fatty acyl-carnitines during 8 weeks of overfeeding: relation to diet energy expenditure and body composition: the PROOF study

George A Bray et al. Metabolism. 2018 Jun.

Abstract

Objective: Overfeeding is a strategy for evaluating the effects of excess energy intake. In this secondary analysis we tested the possibility that different levels of dietary protein might differentially modify the response of fatty acyl-carnitines to overfeeding.

Methods: Twenty-three healthy adult men and women were overfed by 40% for 8 weeks while in-patients with diets containing 5% (LPD), 15% (NPD) or 25% (HPD) protein. Plasma fatty acyl-carnitines were measured by gas chromatography/mass spectrometry (GC/MS) at baseline and after 8 weeks of overfeeding. Measurements included: body composition by DXA, energy expenditure by ventilated hood and doubly-labeled water, fat cell size from subcutaneous fat biopsies, and fat distribution by CT scan.

Results: Analysis was done on 5 groups of fatty acyl-carnitines identified by principal components analysis and 6 individual short-chain fatty acyl carnitines. Higher protein intake was associated with significantly lower 8 week levels of medium chain fatty acids and C2, C4-OH and C 6:1, but higher values of C3 and C5:1 acyl-carnitines derived from essential amino acids. In contrast energy and fat intake were only weakly related to changes in fatty acyl-carnitines. A decease or smaller rise in 8 week medium chain acyl-carnitines was associated with an increase in sleeping energy expenditure (P = 0.0004), and fat free mass (P < 0.0001) and a decrease in free fatty acid concentrations (FFA) (P = 0.0067). In contrast changes in short-chain fatty acyl-carnitines were related to changes in resting energy expenditure (P = 0.0026), and fat free mass (P = 0.0007), and C4-OH was positively related to FFA (P = 0006).

Conclusion: Protein intake was the major factor influencing changes in fatty acyl carnitines during overfeeding with higher values of most acyl-fatty acids on the low protein diet. The association of dietary protein and fat intake may explain the changes in energy expenditure and metabolic variables resulting in the observed patterns of fatty acyl carnitines.

Trial registration: ClinicalTrials.gov NCT00565149.

Keywords: Body fat; Fat cell size; Fat free mass; Fat oxidation; Fatty acyl-carnitines; Overfeeding.

PubMed Disclaimer

Conflict of interest statement

Conflict of Interest Statement

The authors declare no conflicts relative to this manuscript.

Figures

Fig. 1.

Effect of dietary protein on change from baseline in several short-chain fatty acyl-carnitines.

Fig. 2.

Relation of overfed energy intake, protein intake and fat intake to changes in fatty acyl-fatty carnitines in group 2 and group 4 from the principal components analysis.

Fig. 3.

Relation of changes in fat free mass, fat mass, and free fatty acids to changes in acyl-fatty acids in group 2 and group 4 of from the principal components analysis. P value based on regression analysis adjusted for age and sex and the baseline values of group 2 or group 4 and the baseline value of FFM, FM or FFA.

Fig. 4.

Relation of changes in total daily energy expenditure (TDEE), resting energy expenditure (REE) and sleeping energy expenditure (SEE) to changes in acyl-fatty acids in group 2 and group 4 of from the principal components analysis. P value based on regression analysis adjusted for age and sex and the baseline values of group 2 or group 4 and the baseline value of TDEE, REE or SEE.

Fig. 5.

Diagram of fatty acyl-carnitine flux for this study

References

1. Flegal KM, Kruszon-Moran D, Carroll MD, Fryar CD, Ogden CL. Trends in obesity among adults in the United States, 2005 to 2014. JAMA 2016;315(21):2284–91. - PMC - PubMed
1. The Global BMI Mortality CollaborationDi Angelantonio E, Bhupathiraju SN, Wormser D, Gao P, Kaptoge S, et al. Body-mass index and all-cause mortality: individual-participant-data meta-analysis of 239 prospective studies in four continents. Lancet 2016;388:776–86. - PMC - PubMed
1. Bray GA, Kim KK, Wilding JPH. Obesity: a chronic relapsing progressive disease process: a position paper of world obesity. Obes Rev 2017;18(7):715–23. 10.1111/obr.12551 - DOI - PubMed
1. Keith SW, Redden DT, Katzmarzyk PT, Boggiano MM, Hanlon EC, Benca RM, et al. Putative contributors to the secular increase in obesity: exploring the roads less traveled. Int J Obes 2006;30(11):1585–94. - PubMed
1. Hruby A, Manson JE, Qi L, Malik VS, Rimm EB, Sun Q, et al. Determinants and consequences of obesity. Am J Public Health 2016;106(9):1656–62. - PMC - PubMed

Plasma fatty acyl-carnitines during 8 weeks of overfeeding: relation to diet energy expenditure and body composition: the PROOF study - PubMed (original) (raw)