Two sets of researchers from two different continents collaborated in a study that offers insight on why weight rebounds after an initial period of successful weight loss.

Researchers from the University of Michigan and the University of Buenos Aires engineered weight gain in young mice and then reversed this process several times over the lifespan of the mice in an attempt to make the fat mice thin.

What they found was surprising. The longer the weight stayed on the harder it was to keep it off, even after a period of successful weight loss through eating less and exercising more. Over time, it seems, the body permanently resets its initial set point to a heavier weight, meaning that early onset obesity can have lasting effects.

"Our findings show that obesity is a self-perpetuating condition and reinforces the importance of early consultation and weight management in children to prevent obesity, especially when taking into account that the probability of adult obesity exceeds 50% in people who were overweight at 6 years of age," said the researchers.

It also suggests that successful weight management depends on working off excess weight before it decides to stick around permanently.