A new study in mice finds that ursolic acid, a compound naturally present in apple peel, partially protected the animals against obesity and some of its harmful effects such as pre-diabetes and fatty liver disease. Lead researcher Christopher Adams, of the University of Iowa (UI) in the United States, and colleagues, said although they found ursolic acid increased skeletal muscle and brown fat in the mice, which in turn led to increased calorie burning, they didn\'t investigate the underlying biology, and so can\'t say if the same would happen in humans. The team writes about the findings in a paper published online in PLoS ONE on 20 June. In their background information, they describe how they recently found \"ursolic acid increases skeletal muscle Akt activity and stimulates muscle growth in non-obese mice\".