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document
Effects of weight loss and exercise on insulin resistance , and intramyocellular triacylglycerol , diacylglycerol and ceramide . AIMS/HYPOTHESIS Intramyocellular lipids , including diacylglycerol ( DAG ) and ceramides , have been linked to insulin resistance . This randomised repeated-measures study examined the effects of diet-induced weight loss ( DIWL ) and aerobic exercise ( EX ) on insulin sensitivity and intramyocellular triacylglycerol ( IMTG ) , DAG and ceramide . METHODS Sixteen overweight to obese adults ( BMI 30.6 ± 0.8 ; 67.2 ± 4.0 years of age ) with either impaired fasting glucose , or impaired glucose tolerance completed one of two lifestyle interventions : DIWL ( n = 8 ) or EX ( n = 8 ) . Insulin sensitivity was determined using hyperinsulinaemic-euglycaemic clamps . Intramyocellular lipids were measured in muscle biopsies using histochemistry and tandem mass spectrometry . RESULTS Insulin sensitivity was improved with DIWL ( 20.6 ± 4.7 % ) and EX ( 19.2 ± 12.9 % ) . Body weight and body fat were decreased by both interventions , with greater decreases in DIWL compared with EX . Muscle glycogen , IMTG content and oxidative capacity were all significantly ( p < 0.05 ) decreased with DIWL and increased with EX . There were decreases in DAG with DIWL ( -12.4 ± 14.6 % ) and EX ( -40.9 ± 12.0 % ) . Ceramide decreased with EX ( -33.7 ± 11.2 % ) , but not with DIWL . Dihydroceramide was decreased with both interventions . Sphingosine was decreased only with EX . Changes in total DAG , total ceramides and other sphingolipids did not correlate with changes in glucose disposal . Stearoyl-coenzyme A desaturase 1 ( SCD1 ) content was decreased with DIWL ( -19.5 ± 8.5 % , p < 0.05 ) , but increased with EX ( 19.6 ± 7.4 % , p < 0.05 ) . Diacylglycerol acyltransferase 1 ( DGAT1 ) was unchanged with the interventions . CONCLUSIONS/INTERPRETATION Diet-induced weight loss and exercise training both improved insulin resistance and decreased DAG , while only exercise decreased ceramides , despite the interventions having different effects on IMTG . These alterations may be mediated through differential changes in skeletal muscle capacity for oxidation and triacylglycerol synthesis . TRIAL REGISTRATION ClinicalTrials.gov NCT00766298 .
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Intervention_Physical
weight loss
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Intervention_Physical
exercise
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Intervention_Physical
diet-induced weight loss ( DIWL )
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Intervention_Physical
aerobic exercise ( EX )
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Outcome_Physical
spectrometry
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Participant_Condition
insulin resistance