30 Jan Meet Monell: Rebeca Méndez-Hernández on Hunger, the Brain, and Metabolic Disease

Rebeca Méndez-Hernández has always been fascinated by time, specifically how time shapes the way our bodies function. During her PhD, she studied circadian rhythms, the internal biological clocks that influence when we sleep, eat, and carry out our daily activities. But she soon became intrigued by a deeper question: How does the body communicate information about what we’re doing, like eating, to the brain, and how does that information shape our physiology over time?

That question ultimately led her from circadian biology into sensory science, and eventually to Monell Chemical Senses Center, where she is now a postdoctoral fellow in the lab of Guillaume de Lartigue.

“At different times of day, our bodies behave very differently,” Méndez-Hernández explains. “Eating, sleeping, being active. These behaviors don’t just change what we do, they change how our bodies work. I became interested in how sensory information from the body feeds back to the brain and helps regulate those rhythms.”

Going Back to the Basics of Metabolic Disease

At Monell, Méndez-Hernández studies the fundamental biological mechanisms that regulate feeding, metabolism, and physiology, which all share direct implications for understanding obesity and diabetes.

“These are incredibly complex, multifactorial diseases,” she says. “They don’t just affect one system in the body; they affect nearly all of them. That’s why there’s no magic pill that can cure obesity or diabetes.”

Rather than trying to treat these diseases once they’ve already taken hold, Méndez-Hernández believes the key lies in understanding their earliest biological components.

“If we want real, long-term solutions, we need a deep understanding of why we eat what we eat, when we eat, and how our bodies process food under different conditions,” she explains. “Basic science gives us that foundation.”

Interoception: How the Brain Knows What’s Happening Inside the Body

Central to Méndez-Hernández’s work is interoception: the process by which the brain senses the body’s internal state.

“When you feel hungry, that sensation doesn’t come out of nowhere,” she says. “Your brain is receiving signals from inside your body that tell you something is happening.”

In the de Lartigue lab, Méndez-Hernández studies vagal sensory neurons, specialized cells that relay information from organs like the stomach, intestines, and heart to the brain. These neurons are key players in interoception, helping the brain interpret signals such as stomach stretch, nutrient intake, and internal chemical changes.

“What excites me is that different subsets of neurons detect different signals,” she explains. “Some respond to stomach distension, others to sugar, protein, or fat. We’re trying to map how these signals are detected, integrated, and translated into behavior.”

Recent advances in genetic tools now allow researchers to study these pathways with unprecedented precision, something Méndez-Hernández believes could transform the future of medicine.

“These same techniques that we use in mice could eventually be applied to humans,” she says. “That opens the door to truly personalized medicine, where we target only the pathways that are disrupted in a specific person, rather than using one-size-fits-all drugs with broad side effects.”

A Commitment to Basic Research, Even When Impact Isn’t Immediately Obvious.

“Basic science can feel far removed from everyday life,” she says. “But everything we know—from how mitochondria work to how neurons communicate—came from basic research done years ago.”

She likens it to untangling a ball of yarn.

“When metabolic disease starts, it’s like a small knot. Over time, it becomes a massive tangle that affects blood pressure, blood sugar, and overall health,” she explains. “Our job is to understand the system before it becomes that tangled, to see how the threads connect before the damage is done.”

That early understanding, she says, is what ultimately makes effective prevention and treatment possible.

Life as a Postdoc at Monell

No two days look the same for Méndez-Hernández. Her work includes running experiments and surgeries, writing papers and grants, mentoring students, presenting at conferences, and communicating science to broader audiences.

“As a postdoc, you really get exposure to every aspect of science,” she says. “It’s challenging, but it’s also incredibly fun.”

She credits Monell’s collaborative culture for helping her thrive.

“Monell is small compared to a university, and that’s a huge advantage,” she says. “You get real, one-on-one interactions with scientists from many different disciplines, and people are genuinely excited to share ideas.”

That interdisciplinary environment, combined with strong institutional support for training and career development, has played a major role in her growth as a scientist.

Looking Ahead

For Méndez-Hernández, the future of her field is full of possibility.

“We now have the tools to precisely manipulate specific neural circuits,” she says. “That precision allows us to understand what each pathway does, and eventually, to target only what a patient actually needs.”

She’s proud of the work she does and the community she’s part of.

“I’m proud to be a researcher at Monell,” she says. “We’re pushing the boundaries of what we know, and that knowledge has the potential to make a real difference in the world.”