Obesity May Be Irreversible In The Long Run
October 25, 2012

Study Finds It Is More Difficult To Lose Weight Over Time

Connie K. Ho for redOrbit.com — Your Universe Online

A new study is calling into question the viability of long-term weight loss. Researchers at the University of Michigan and the National Council of Science and Technology, an Argentina-based organization, recently discovered that timing is a factor with weight loss and that the longer that people are overweight, the more difficult it is to shed the pounds.

The study included a group of overfed-mice who stayed obese and who were less likely able to change their diet and activity if they were overweight for a long period of time. The longer the mice stayed overweight, the more “irreversible” obesity remained. The researchers believe that, over time, the animals' obese state led to a resetting of the “normal” body weight and that point eventually became permanently higher than normal, even if the mice were consistently working to lose weight via diet changes.

“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,” explained the study´s senior author Dr. Malcolm J. Low, a professor of molecular and integrative physiology and internal medicine at the university of Michigan, in a prepared statement. “Our new animal model will be useful in pinpointing the reasons why most adults find it exceedingly difficult to maintain meaningful weight loss from dieting and exercise alone.”

The researchers believe that one of the positive results of the study was the creation of a new model of obesity, where the team of investigators tracked the weight loss of mice at different stages and ages by using a genetic switch targeting hunger. When the switch was turned on right after the weaning of the mice, it allowed the mice to not overeat and become obese. Mice that maintained a normal weight by consuming a healthy diet were able to keep the weight off after turning the switch on. On the other hand, mice that were chronically overfed were never able to return to their normal weight after the genetic switch was turned on. Changes that the mice underwent included a decrease in food consumption and an increase in physical activity.

Based on the findings of the project, it is unclear as to whether calorie restriction and intense exercise regimes will help people have long-term weight loss.

“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,” continued Low in the statement. “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 study highlights the detrimental effects of obesity. According to the researchers, over 500 million adults and 43 million children younger than five years of age are currently suffering from obesity. Those who are considered overweight have an elevated risk of developing various cardiovascular diseases, hypertension and type 2 diabetes.

The findings are published in the online edition of the Journal of Clinical Investigation.