25/10/2012 11:56 BST | Updated 25/10/2012 17:25 BST

Study Reveals Why Weight 'Comes Back' (Plus - Surprising Things That Make You Fat)

New research has shed light on one of the most frustrating mysteries of dieting: why the weight inevitably comes back.

According to a study by University of Michigan and the Argentina-based National Council of Science and Technology (CONICET), a study of mice demonstrated that the longer mice remain overweight, the more "irreversible" obesity becomes.

Senior author Malcolm Low said in a statement: "Our model demonstrates that obesity is in part a self-perpetuating disorder and the results further emphasise the importance of early intervention in childhood to try to prevent the condition whose effects can last a lifetime." reveal diet tips:

7 Surprising Things That Make You Fat

The new findings could raise questions about the long-term success rate of severe calorie restriction and strenuous exercise used later in life to lose weight.

Low says: "Somewhere along the way, if obesity is allowed to continue, the body appears to flip a switch that re-programs to a heavier set weight."

"The exact mechanisms that cause this shift are still unknown and require much further study that will help us better understand why the regaining of weight seems almost unavoidable."

The research is published in the Journal of Clinical Investigation.