Drug to stop yo-yo dieting a real possibility after weight gain ‘switch’ found in brain

COLOGNE, Germany — A pill that stops yo-yo dieting may be on the horizon thanks to an important discovery by researchers at the Max Planck Institute for Metabolism Research and Harvard Medical School. Scientists identified a “switch” in the brain that causes people to regain the pounds shed. Turning it off would prevent piling them back on, according to new research.

Previous research has shown that yo-yo dieting, a term used to define weight fluctuations from starting and stopping diets, can be harmful for longterm health. One recent study reports that yo-yo dieting raises the risk of heart disease and diabetes.

With the new discovery, scientists could now develop new therapies to target this “switch” and help people keep the pounds off for good. “This could give us the opportunity to diminish the yo-yo effect,” says lead author Dr. Henning Fenselau in a statement.

Dieting causes us to burn more fat to boost energy, putting the brain in “famine mode.” Afterwards, the body goes back to storing fat as normal, making up for the lost calories. Now, the international team have discovered the chemical pathway behind the phenomenon. Blocking it in slimmed down mice led to them keeping their leaner physiques.

“People have looked mainly at the short-term effects after dieting. We wanted to see what changes in the brain in the long term,” says Dr Fenselau.

Yo-yo dieting drug could keep people from regaining weight after a diet

The study found that dieting profoundly changes the way some brain cells communicate. They control feelings of hunger and lie in an area called the hypothalamus, and are known as AgRP neurons. Lab rodents ate significantly more afterwards and gained weight rapidly because the neurons were receiving stronger signals.

It started when the mice were on a diet and could be detected for a long time subsequently. But when the researchers selectively inhibited the AgRP neurons it led to much less weight gain. The finding opens the door to developing a drug that achieves the same results in humans.

“In the long term, our goal is to find therapies for humans that could help maintaining body weight loss after dieting,” says Dr Fenselau. “To achieve this, we continue to explore how we could block the mechanisms that mediate the strengthening of the neural pathways in humans as well.”

Another recent study of almost seven million people in South Korea found those who went though yo-yo dieting were over twice as prone to premature death. A host of celebrities have struggled with yo-yo dieting including Lady Gaga, Mariah Carey, Jessica Simpson and Christina Aguilera.

“This work increases understanding of how neural wiring diagrams control hunger.

“We had previously uncovered a key set of upstream neurons that physically synapse onto and excite AgRP hunger neurons,” adds co-author Bradford Lowell, of Harvard Medical School. “In our present study, we find the physical neurotransmitter connection between these two neurons, in a process called synaptic plasticity, greatly increases with dieting and weight loss, and this leads to long-lasting excessive hunger.

The study is published in the journal Cell Metabolism.

South West News Service writer Mark Waghorn contributed to this report.