Iso-Energetic Low Carbohydrate/High Fat Energy Intake Increases Intramyocellular Lipid Content In Skeletal Muscle - Independent Of Caloric Intake

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SUN 702-709-Obesity: Response to Interventions
Sunday, June 16, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SUN-706
Ayse Zengin*1, Amon Horngacher2, Sarina Meurer3, Maximilian Bielohuby1 and Martin Bidlingmaier1
1Ludwig-Maximilians University, Munich, Germany, 2Ludwig-Maximilians University, Munich, 3Ludwig-Maximilians University
The efficacy of “Atkins-style” low-carbohydrate/high fat diets (LC-HFD) as a weight loss method has been well established in both animals and humans. Weight loss during obesity has been shown to improve insulin sensitivity. We have previously shown that rats fed LC-HFD exhibit reduced insulin sensitivity, despite significant weight loss. Increased intramyocellular lipids (IMCL) have been associated with decreased insulin sensitivity and impaired glucose tolerance. Therefore, we investigated whether pair-feeding isoenergetic amounts of 2 different LC-HFD affects skeletal muscle lipid content. Male Wistar rats (12-wk) were isoenergetically pair-fed on chow (CH), “Atkins-style” LC-HFD1, (protein matched to CH, 78.7/19.1/2.2); and ketogenic LC-HFD2 (low protein content, 92.8/5.5/1.7) (% of metabolisable energy, fat/protein/carbohydrate) for 4 weeks. Characterisation of the insulin/glucose phenotype was determined via oral glucose (oGTT) and insulin tolerance tests (ITT). IMCL content was determined in cryosections of the gastrocnemius which were stained with oil red-O. Triglycerides were extracted from the quadriceps muscles and levels were measured by colorimetric absorptiometry. In comparison to CH, rats fed LC-HFD displayed higher glucose concentrations during oGTT, with no differences between LC-HFD1 and LC-HFD2. ITT resulted in a less pronounced decrease in glucose in both LC-HFD compared to CH groups (glucose levels after 120 min (mg/dl): CH: 42.7+1.7; LC-HFD1: 75+3.6; LC-HFD2: 93.1+6.5, p<0.01), with no differences between LC-HFD1 and LC-HFD2 groups. Gastrocnemius oil red-O stained sections exhibited more IMCL in both LC-HFD groups compared to CH. Preliminary findings revealed no differences in triglyceride levels within the quadriceps between groups. Muscle fiber type plays a large role in fatty acid metabolism, with a greater capacity in type I muscle fibers (quadriceps) compared to type II muscle fibers (gastrocnemius). This may have contributed to the difference in lipid content seen within the gastrocnemius and the quadriceps. Taken together, increased skeletal muscle IMCL may contribute to the aberrant glucose metabolism in response to LC-HFD. Interestingly, this effect was independent of the relative abundance of fat and protein in LC-HFD.

Disclosure: MB: Consultant, Immunodiagnostic Systems. Nothing to Disclose: AZ, AH, SM, MB

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