Effects of Reduction in Saturated Fat on Cholesterol and Lipoproteins in Lean and Obese Persons

Background: Increased intake of saturated fat may influence LDL cholesterol and other cardiovascular risk factors different in normal weight and obese subjects. Methods: The study is a randomized controlled clinical trial in 84 men and women between 21 to 70 years with normal BMI (25 kg/m2) or obesity (BMI 30-45 kg/m2) and elevated LDL cholesterol (\>3.0 mmol/l). Dietary intervention: Randomization will be to one of two balanced weight maintenance Mediterranean-type diets that differ in their fat sources: an intervention diet substituting unsaturated fats from oil and nuts for saturated fats from meat and dairy foods, and a control diet with whole fat dairy and meat with saturated fats that are not fat reduced. Primary research question: Compare the effect of substitution of unsaturated fat from nuts and oils for saturated fat from meat and dairy foods on serum lipids in normal weight and obese subjects with elevated LDL cholesterol. Secondary research questions: Compare the effect of substitution of unsaturated fat from nuts and oils for saturated fat on cardiometabolic risk factors including insulin resistance, inflammation and serum PCSK9 in normal weight and obese individuals.