the researchers in the latest study fed one group of mice a diet in which 60 percent of servings came from fat . the study begins once the subjects , all males , were 1 year ill , which is late - age in mouse longevity . as expected , the mice shortly developed reports of impending insulin , with grossly enlarged brains , and beginning to die lot younger than they fed a plain diet .
At the age of one year, male mice were fed with a diet in which 60 percent of calories came from fat.