Relationship between utilization of fat and synthesis of cholesterol and total lipid in young female rats

Young adult female rats were fed diets containing 2% of calories from corn oil plus 20, 40, 60 or 80% of calories as beef tallow or diets containing 2% corn oil and the calorie allowance restricted to 80, 60, 40 or 20% of ad libitum consumption. Incorporation of C14‐acetate into cholesterol and total fat was determined as an indication of rate of synthesis. As dietary fat was increased there was a linear increase in cholesterol radioactivity, as measured in serum, liver and carcass. As calories were decreased there were small but significant increases in cholesterol radioactivity. There was a highly significant decrease in incorporation of acetate into total fat as dietary fat increased, and a decrease in total fat radioactivity when calorie intake was restricted. The differences in rate of cholesterol biosynthesis were not accompanied by differences in total quantity of cholesterol. The conclusion reached was that utilization of fat for energy results in accelerated cholesterol biosynthesis.