London - An apple a day could keep flab at bay – as long as you eat the peel.

The chemical responsible for the apple skin’s waxy sheen is credited with helping the body burn extra calories.

Mice fed fatty food laced with ursolic acid ate more but put on less weight than those eating the same meals without the chemical.

It also seemed to keep blood-sugar levels in check and stop the liver becoming clogged up with fat, reports the journal PLoS ONE.

The study showed ursolic acid, also found in cranberries and prunes, could boost muscle and “brown” fat, a calorie-hungry type of fat common in babies.

Dr Christopher Adams of the University of Iowa said: “Since muscle is very good at burning calories, the increased muscle in the ursolic acid-treated mice might be sufficient to explain how ursolic acid reduces obesity.

“We were surprised to find ursolic acid also increased brown fat, a fantastic calorie burner.”

Dr Adams now wants to work out if apple peel is as good for people as it is for mice. - Daily Mail