Mice were fed on natural ingredient, standard NIH-31 diet and analyzed at 7–9 weeks (young) or 10 months (old). A. Hepatic steatosis in old, but not young mice. Liver sections stained with H&E. B. Elevated liver triglycerides in old, but not young mice. C. Elevated serum ALT in old, but not young mice. D. Depletion of respiratory complexes II and IV in old, but not young mice. E. Depletion of Mfn2 in old, but not young mice. F. Decreased levels of ATP in old, but not young mice. Data represent mean ± SD. * indicates p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001, ns not significant, as determined by 2-way ANOVA with Bonferroni multiple comparison test.