Consuming a whole apple every day could do more than ward off disease: It could also help combat obesity and help prevent metabolic diseases such as diabetes.
The key is ursolic acid, a compound naturally found in apple peels, researchers at the University of Iowa found. In a mouse study, a daily supplement of the acid protected mice against obesity and some obesity-related conditions, such as pre-diabetes or fatty liver disease
Ursolic acid isn't a magic obesity fighter, but rather it helps increase skeletal muscle mass and brown fat in non-obese mice, researchers explain in the journal PLoS ONE. More research needs to be conducted to determine if the acid would have the same effect in humans.
Increasing muscle mass is the one surefire way to boost metabolism in humans because one pound of muscle burns more calories at rest than one pound of fat. Brown fat is the "good" type of fat in your body that insulates you from cold and generates heat and fuel, as opposed to white fat, which just stores calories for future use. When you're cold, your brown fat deposits activate and burn additional calories to keep your body temperature up. Although another recent study published in the Journal of Clinical Investigation found that brown fat mass may protect against obesity, it's still not entirely clear how and why the human body uses brown fat stores. (Until recently, scientists believed that brown fat was only present in infants.)
How Ursolic Acid Works
In the background information in the new study, researchers explain that it was only recently discovered that ursolic acid increases the activity of the protein Akt, which plays an important role in burning glucose to make energy.
To test ursolic acid's abilities, researchers fed the compound to mice on a high-fat diet and compared the results to mice on a high-fat diet who were not taking the compound. They found that the mice who took the acid actually ate more food than the other mice, but maintained more normal blood-sugar levels and gained less weight than the mice who did not take the acid. There was also no sign of fatty-liver disease in the ursolic acid group.
Because of the increase in muscle and brown fat, the ursolic acid group actually burned more calories than the non-supplement group, even though they consumed more calories. More work needs to be done to determine how humans can increase their levels of brown fat.
"At this point, we don't know how ursolic acid increases brown fat, or if it increases brown fat in healthy mice," leader researcher Christopher Adams, MD, PhD, said in a university release. "And, most importantly, we don't know if ursolic acid will benefit people. Our next step is to determine if ursolic acid can help patients."
source: http://www.everydayhealth.com/weight/0622/can-an-apple-a-day-keep-obesity-away.aspx
source: http://www.everydayhealth.com/weight/0622/can-an-apple-a-day-keep-obesity-away.aspx