A researcher in Broward County, Florida designed an investigation to test what effect eating different types of food would have on blood insulin levels. She selected 10 male
subjects who were all 25 years of age and in good health. The experiment took place
over 3 days. At 8:00 a. m. on each day, the subjects ate a meal consisting of only 1 type
of food. They had their blood insulin levels measured after consurning the meal. On Day
1 they ate a high fat diet, on Day 2 they ate a high protein diet, arnd on Day3 they ate a
high sugar diet.
What is the independent variable in this experiment?