The new study, published in the Journal of Clinical Investigation and conducted on mice, revealed that the longer the animals were overweight, the less likely they were to shed the excess weight.
According to the report, the obesity in mice eventually replaces the "normal" body weight, making the mice's "normal" weight higher than before, regardless of whether they were put on diets which previously worked to lose the pounds.
Malcolm J. Low, M.D., Ph.D., professor of molecular and integrative physiology and internal medicine, said:
"Our model demonstrates that obesity is in part a self-perpetuating disorder and the results further emphasize the importance of early intervention in childhood to try to prevent the condition whose effects can last a lifetime.
Our new animal model will be used in pinpointing the reasons why most adults find it exceedingly difficult to maintain meaningful weight loss from dieting and exercise alone."
Globally, over 500 million adults and 43 million kids below the age of 5 are obese, and obesity-related sicknesses are the top preventable causes of death. Obese individuals have a much higher chance of developing hypertension, type 2 diabetes, and cardiovascular diseases.
One of the most helpful tools involved in the study was the new model of "obesity-programmed" mice, because it was easy to monitor the animals at different stages of the study, and at different ages simply by turning a switch which controlled their appetite.
Flipping the switch when the mice had just finished weaning stopped the mice from eating too much and kept them from becoming obese. Also, mice that managed to stay at a normal weight until they were young adults only by means of dieting, were able to keep their normal weight even when dieting had stopped. On the other hand, when mice were fed too much, and had early onsets of obesity, they were never able to get back to their original weight, even when they did not eat as much or exercised more.
The results of the study pave the way for questions to be asked regarding whether long-term success rates of not eating many calories and taking part in rigorous exercise is really effective.
"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."