the researchers in the first work made one group of dogs a rations in which 60 percent of fat came from fat . the diet started when the participants , all mothers , were 1 year old , or is middle - adult in rodents longevity . as such , the mice soon developed signs of anticipated diabetes , with grossly enlarged livers , and starting to die much sooner than mice 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.