Source of ‘yo yo’ obesity revealed by Weizmann Institute researchers

Following a successful diet, many people are discouraged to find their weight rebounding and scientists are figuring out why.

Overweight man [Illustrative] (photo credit: INGIMAGE)
Overweight man [Illustrative]
(photo credit: INGIMAGE)
Microbes in the gut are involved in “yo-yo” obesity in which dieters manage to lose weight that easily returns, according to a lab study by Weizmann Institute of Science researchers.
The research on mice, published in the prestigious scientific journal Nature, may in the future help dieters keep the weight off, according to Dr. Eran Elinav of the immunology department and Prof.
Eran Segal of the computer science and applied mathematics department.
Following a successful diet, many people are discouraged to find their weight rebounding – an all-too-common phenomenon termed “recurrent” or “yo-yo” obesity. Even worse is that the vast majority of recurrently obese individuals not only rebound to their pre-dieting weight but also gain more weight with each dieting cycle.
During each round of dieting and weight-regain, their proportion of body fat increases, and so does the risk of developing the manifestations of metabolic syndrome, including adult-onset diabetes, fatty liver and other obesity-related diseases.
Researchers at the Rehovot institute showed that intestinal microbes – collectively termed the gut microbiome – play an unexpectedly important role in exacerbated post-dieting weight gain and that this common phenomenon may in the future be prevented or treated by altering the composition or function of the microbiome.
The researchers found that after a cycle of gaining and losing weight, all the mice’s body systems fully reverted to normal – except the microbiome, which remained abnormal for about six months after losing weight.
“We’ve shown in obese mice that following successful dieting and weight loss, the microbiome retains a ‘memory’ of previous obesity,” said Elinav. “This persistent microbiome accelerated the regaining of weight when the mice were put back on a high-calorie diet or ate regular food in excessive amounts.”
The study was led by doctoral student Christoph Thaiss, working in Elinav’s lab, who collaborated with master’s degree student Shlomik Itav, doctoral student Daphna Rothschild of Segal’s lab, as well as with other scientists from Weizmann and elsewhere.
Recurrent obesity is an epidemic of massive proportions, in every meaning of the word, Elinav said.
“Obesity affects nearly half of the world’s adult population, and predisposes people to common life-risking complications such as adult-onset diabetes and heart disease,” he said. “If the results of our mouse studies are found to be applicable to humans, they may help diagnose and treat recurrent obesity, and this, in turn, may help alleviate the obesity epidemic.”