the researchers in the latest survey fed some group of mice a diet in which 60 percent of calories came from fat . the diet started when the mice , all males , were 1 year old , which is high - term in rat longevity . as expected , the population soon developed signs of impending diabetes , with grossly expanded liver , and started to die much sooner than mouse fed a standard diet .
At the age of one year, male mice were fed with a diet in which 60 percent of calories came from fat.