Eat more, weigh less? Study provides clues for new fat-loss therapies in humans

Anyone who’s attempted to lose weight by cutting calories and logging more treadmill time has probably wished for a way to somehow speed up their slimdown.

Now, scientists at The Scripps Research Institute (TSRI) in San Diego, Calif. have pinpointed two important neurotransmitters – serotonin and adrenaline – which might someday play a role in the development of pharmacological solutions for people who want to burn fat faster.

According to lead study author Dr. Supriya Srinivasan, an assistant professor at TSRI, previous research had shown that manipulating serotonin, a neurotransmitter that helps regulate mood, facilitates the loss of body fat in both humans and mice. However, the mechanisms behind this reaction were not well understood.

Driven by a desire to delve deeper into the relationship between serotonin and fat loss, Srinivasan decided to study the weight-loss circuitry of a type of roundworm known as C. elegans.

In a study published in Cell Metabolism, Srinivasan was able to determine that while serotonin does help trigger fat loss, it works better when combined with adrenaline.

“What we found is you can activate fat loss by just giving serotonin but in order to do that you need some amount of adrenaline to be present. If you take away the adrenaline-like component of the signaling, the serotonin still works but the efficacy is greatly reduced,” Srinivasan told FoxNews.com. “The same is true for the adrenalin-like signaling…Each part of the circuit, or each neurotransmitter, requires the other.”

Furthermore, Srinivasan was able to confirm that altering serotonin and adrenaline facilitated weight loss in worms regardless of how much food they were consuming.

“We found that the receptors that control feeding behavior are distinct and separate from the ones that control fat loss,” Srinivasan said. “The reason you see fat loss in serotonin-treated animals is because they are burning more fat and expending more energy.”

Though human applications for these findings are still speculative, Srinivasan notes that the study might help pave the way for better weight loss drugs in the future.

In fact, the now-banned weight loss drug Fen-Phen was a serotonin-plus-adrenaline-boosting therapy, according to Srinivasan. The drug became notorious in the 1990s for producing rapid weight loss in users – along with sometimes-fatal cardiovascular side effects.

However, if researchers could figure out a safer way to boost serotonin, they may be able to improve weight loss outcomes without the negative side effects, according to Srinivasan.

“One potential avenue would be instead of giving combination serotonin and androgenic-like drugs like Fen-Phen that lead to cardiovascular effects, (we could find) ways to use adrenaline-like signaling to boost neural serotonin,” Srinivasan said.