Intramyocellular lipid content is lower with a low-fat diet than with high-fat diets, but that may not be relevant for health.
BACKGROUND
Fat deposition in muscle has been found to be related to metabolic risk.


OBJECTIVE
This study compared soleus intramyocellular lipid (IMCL) concentrations after consumption of weight-maintaining, controlled diets differing in total fat and fat type.


METHODS
This study consisted of 3 phases of 25 d each in a crossover, controlled feeding design. The low-fat (LF) diet provided 30.8% and 5.2% of energy from fat and polyunsaturated fat (PUFA), respectively. Two higher-fat diets were tested: the high-fat (HF) diet provided 37.9% and 5.8% of energy from fat and PUFA, respectively, and the high-PUFA (HPUFA) diet provided 36.3% and 9.7% of energy from fat and PUFA, respectively. Twenty-four men and women [age range: 19-65 y; body mass index (in kg/m(2)): 20-35] whose LDL and glucose concentrations were between 130 and 180 mg/dL and <126 mg/dL, respectively, completed all study phases.


RESULTS
IMCL content was 1.88 times as high after the HF diet (P = 0.005) and 1.71 times as high after the HPUFA diet (P = 0.002) as after the LF diet. There was no significant correlation between percentage fat mass or waist circumference and IMCL content. With pooled data from all diets, there was no significant correlation between IMCL content and insulin or glucose concentration. There was no significant difference in IMCL content in subjects with or without the metabolic syndrome or in subjects with LDL particle pattern A or B.


CONCLUSIONS
Our results suggest that IMCL content is not modulated by dietary fat type but by total fat intake and that reducing fat intake effectively lowers IMCL. However, the metabolic implications of having lower IMCL concentrations are not clear.
St-Onge
Marie-Pierre
MP
Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham, AL, USA. ms2554@columbia.edu
Newcomer
Bradley R
BR
Buchthal
Steven
S
Aban
Inmaculada
I
Allison
David B
DB
Bosarge
Aubrey
A
Gower
Barbara
B
D000328:Adult; D000368:Aged; D018592:Cross-Over Studies; D004041:Dietary Fats / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D008055:Lipids / Q000032:analysis*; D008077:Lipoproteins, LDL / Q000032:analysis; D008297:Male; D008875:Middle Aged; D032342:Muscle Cells / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism*
D004041:Dietary Fats; D008055:Lipids; D008077:Lipoproteins, LDL