Rationale: High rates of de novo lipogenesis (DNL) and high saturated fatty acid (SFA) fraction in the liver both have been associated with poor metabolic health and hepatic insulin resistance. Interestingly, the end product of DNL is mainly SFA. So far it is unknown whether it is the process of DNL or the accumulation of SFA per se that leads to hepatic insulin resistance. This is a clinically relevant question, as it will give novel insights towards the best strategy for prevention and treatment of hepatic insulin resistance. Therefore, it is of interest to compare the effect of a diet that modifies directly hepatic SFA content (high SFA diet) and a diet that changes SFA indirectly by modifying rates of DNL (high fructose diet).~Objective: To determine the effect of a 4-week high SFA diet compared to a 4-week high fructose diet on hepatic insulin sensitivity, on hepatic SFA fraction and DNL.~Study design: This is a randomized intervention study comparing the effects of a 4-week high SFA diet compared to a 4-week high fructose diet on hepatic insulin sensitivity.~Study population: 24 overweight/obese, but otherwise healthy, males and females (BMI 27-38 kg/m2), 45-75 years, will participate in the study. Of these 24 included participants, 18 are expected to meet the study criteria and take part in the measurements following the screening, of these 14 need to complete the study.~Intervention: Participants follow a 4-week high SFA diet and a 4-week high fructose diet.~Main study parameters/endpoints: The primary outcome is hepatic insulin sensitivity (suppression of EGP during clamp) upon a 4-week high SFA diet versus a 4-week fructose diet. Secondary outcomes are DNL upon 4-week high SFA versus 4-week high fructose, and delta (baseline-end intervention) hepatic SFA fraction upon 4-week high SFA versus 4-week high fructose.
High rates of de novo lipogenesis (DNL) and high saturated fatty acid (SFA) fraction in the liver both have been associated with poor metabolic health and hepatic insulin resistance. Interestingly, the end product of DNL is mainly SFA. So far it is unknown whether it is the process of DNL or the accumulation of SFA per se that leads to hepatic insulin resistance. Therefore, it is of interest to compare the effect of a diet that modifies directly hepatic SFA content (4-week high SFA diet) and a diet that changes SFA indirectly by modifying rates of DNL (4-week high fructose diet). To this end, 18 overweight/obese, but otherwise healthy, males and females will take part in the randomized dietary interventions. The primary outcome is hepatic insulin sensitivity (suppression of EGP during clamp) upon a 4-week high SFA diet versus a 4-week fructose diet.