Habitual physical activity is associated with intrahepatic fat content in humans.
OBJECTIVE
Fatty liver may be involved in the pathogenesis of type 2 diabetes. Physical exercise is a tool to improve insulin sensitivity, but little is known about its effect on intrahepatic fat (IHF) content. The purpose of this study was to examine the association of habitual physical activity, insulin resistance, and adiponectin with IHF content.


METHODS
Participants were 191 (77 female and 114 male) apparently healthy, nonalcoholic individuals (aged 19-62 years; BMI 17.0-35.5 kg/m2). IHF content was assessed in a quantitative fashion and noninvasively as a continuous variable by means of 1H magnetic resonance spectroscopy (MRS), and habitual physical activity was assessed by means of a questionnaire. Fatty liver was defined as IHF content of >5% wet weight, and insulin sensitivity was estimated using the computer homeostasis model assessment (HOMA)-2 indexes.


RESULTS
A reduced prevalence of fatty liver in the quartile of the most physically active individuals (25, 11, 25, and 2% in quartile 1, 2, 3, and 4, respectively; chi2 = 15.63; P = 0.001) was found along with an inverse correlation between the physical activity index and the IHF content when plotted as continuous variables (Pearson's r = -0.27; P < 0.000). This association was not attenuated when adjusted for age, sex, BMI, HOMA-2, and adiponectin (partial correlation r = -0.25; P < 0.001).


CONCLUSIONS
This study demonstrated that a higher level of habitual physical activity is associated with a lower IHF content and suggested that this relationship may be due to the effect of exercise per se.
Perseghin
Gianluca
G
Internal Medicine, Section of Nutrition/Metabolism, San Raffaele Scientific Institute, Milan, Italy. perseghin.gianluca@hsr.it
Lattuada
Guido
G
De Cobelli
Francesco
F
Ragogna
Francesca
F
Ntali
Georgia
G
Esposito
Antonio
A
Belloni
Elena
E
Canu
Tamara
T
Terruzzi
Ileana
I
Scifo
Paola
P
Del Maschio
Alessandro
A
Luzi
Livio
L
D000273:Adipose Tissue / Q000033:anatomy & histology*; D000328:Adult; D001794:Blood Pressure; D015444:Exercise; D005234:Fatty Liver / Q000517:prevention & control*; D005260:Female; D006801:Humans; D008099:Liver / Q000033:anatomy & histology*; D008297:Male; D008875:Middle Aged; D010809:Physical Fitness; D015995:Prevalence; D012016:Reference Values