To determine differences between NAFLD and NASH subjects with respect to hepatic FA metabolism (uptake, oxidation, and re-esterification) and hepatic VLDL-TG secretion and peripheral kinetics (oxidation and tissue storage). 8 non-diabetic upper-body obese subjects with NAFLD and 8 with NASH (biopsy proven) will be studied in the overnight fasted state. VLDL-TG stable isotope will be used in combination with hepatic vein catherization to directly measure splanchnic VLDL-TG uptake and secretion. FFA (palmitate) tracers as well as adipose tissue and skeletal muscle biopsies will be used to measure whole-body substrate turnover and flexibility as well as tissue specific substrate handling during fasting and hyperinsulinemic conditions.

Inclusion Criteria:

• 8 obese subject men with NAFL (MR spectroskopi, fibro scanner) (BMI > 28).
• 8 obese subject men with NASH (MR spectroskopi, fibro scanner) (BMI > 28). age between 40-70 years. Written consent before the start of the study.

Exclusion Criteria:

• known current disease
• fixed medical drug consumption except antihypertensive drugs and statins. However, pause statins 3 weeks before the examination date Blood donation within the last 3 months prior to the study Participation in experiments involving radioactive isotopes within the last 3 months Alcohol abuse (over 21 items per week for men and 14 for women) Smoking Weight over 130 kg Cancer patients Large intake of medication

8 obese subject men with NAFL (MR spectroskopi, fibro scanner) (BMI > 28).

- 8 obese subject men with NASH (MR spectroskopi, fibro scanner) (BMI > 28). age between 40-70 years.