Meet Carol McCarthy: Our Functional Genomics Coach on Blood Sugar, Genetics, and Brain Health
By Dr. Cynthia Libert, Functional Medicine Physician | Caring for the Body, Center for Functional Medicine
This post is adapted from the Re-Think Aging podcast. You can listen to the full episode here: https://www.youtube.com/watch?v=e9asVeT4_GM
This month inside our Re-Think Aging community, we have been focusing on blood sugar balance, insulin resistance, and how deeply these topics are intertwined with our brain health, our energy, our mood, and our long-term resilience.
Today I get to introduce you to one of our newest and most remarkable team members, Carol McCarthy. Carol holds a master's degree in biophysics and genetics, and she brings a rare combination of deep scientific rigor and a heart of compassion into her work with our patients. She is our functional genomics coach.
Carol's Journey
Carol shared her own health story with us. She fell in love with science in the eighth grade, and that love carried her through a biochemistry degree and then graduate school in biophysics and genetics. But after years in the lab, she realized she wanted to take the science of human biology and apply it directly to people's lives, so she became a genetic counselor.
Then, in her mid-30s, married with three small children, she was diagnosed with cancer. She did everything her doctors told her, including chemotherapy and surgery. A year later, she asked them what she should do to keep the cancer from coming back. Their answer stopped her cold: "Nothing. You don't do anything. When your cancer comes back, you come back to see us, and we'll treat you again."
She could not accept that. She went back to the research, found a whole world of people approaching cancer from a holistic and preventative perspective, and started changing her diet, exercising, and managing her stress. But within a year of finishing chemotherapy, she was diagnosed with one autoimmune disease after the next. Even while doing everything right, she kept getting sick.
That search for answers led her into the world of functional medicine, and as she put it, "that really changed my life. I cannot believe all the answers that I found... it really helped turn my life around and bring me my own path back to wellness."
I shared with Carol that it is clear to me her journey has been redemptive, full of meaning and purpose, and that we share a common faith that infuses the suffering and challenges we go through with an extra layer of meaning, because we know there is a reason behind it.
What Is Functional Genomics?
Carol broke this term down beautifully. In genetics, there are two key terms: your genotype, your actual genetic code or instruction manual, and your phenotype, which is you. How you show up in the world.
"Functional genomics is the science of how lifestyle, what you eat, do you exercise, how much stress you undergo and exposures, toxic exposures, infectious exposures... influence your genotype, that code, to inform your phenotype."
She used a metaphor I love. Think about your genetic code as keys on a piano. Every piano around the world has the same black and white keys. Your lifestyle and your exposures are your sheet music, the music you choose to play throughout your life. As Carol said, "What I love about genomics is we have control over the sheet music. We can pick different sheet music."
This is the hopeful field of epigenetics. You are not simply stuck with the genes you were given. You have real influence over how those genes express themselves.
Understanding SNPs
Carol also explained SNPs, or single nucleotide polymorphisms, a term I use with my patients every day in the clinic.
She described our chromosomes as books, our genes as the chapters within those books, and SNPs as small variations in the spelling of individual words in our genetic code. As she put it, "at the snip level, every single one of us has thousands of variations in the spelling of the words in our genetic code. That's what makes us unique."
Blood Sugar, Insulin, and Your Brain
Carol has a wonderful way of making complex science understandable. She described insulin as a shuttle bus. Our pancreas releases insulin when it senses glucose in the bloodstream, and insulin picks up that glucose and drives it to our cells, where it becomes energy.
The trouble is that in our modern world, food is abundant, tasty, and often loaded with sugar or refined starches that turn into glucose very quickly. Our pancreas has to send out more and more shuttle buses. Over time, this system can start to break down. Insulin stops working as well as it should. That is insulin resistance.
"If that continues, continues and continues, then eventually the pancreas says, 'Oh, forget it. I'm not making insulin anymore.'" That is diabetes.
And this does not just affect the body from the neck down. As Carol explained, when there is extra glucose in the brain that is not getting into the cells, that is neuroinflammation. When brain cells are not making enough energy, that shows up as brain fog, poor memory, and difficulty planning, calculating, and staying motivated.
The bottom line is that we are overfed and undernourished, and the extra calories we take in get deposited as fat, particularly visceral fat, which drives insulin resistance in the body and in the brain. In fact, many researchers are now calling Alzheimer's disease "type three diabetes," or insulin resistance in the brain.
Why Some Healthy People Still Struggle
One of the most important parts of our conversation addressed something I hear from patients often. Someone can be slender, exercising, and eating well, and still have profound insulin resistance. Carol explained that certain SNPs set the stage for this vulnerability, while diet, sleep, movement, stress, and toxin exposure influence how those genes are triggered.
She walked through four specific examples:
- MTNR1B, tied to melatonin and insulin suppression, which can leave people waking up with high fasting glucose even after a good night's sleep. Sleep hygiene, morning sunshine, stress management, and a walk after dinner all help support this one.
- TCF7L2, the strongest SNP variant associated with diabetes, tied to GLP-1 secretion. Carol recommends early testing, even in your 30s, along with high intensity interval training, strength training, and a low glycemic, higher fiber diet.
- SLC2A2, which affects how well your pancreas senses glucose in the first place. Movement after every meal helps the body catch up.
- PPARG, which decreases insulin sensitivity and increases fat storage, especially with belly fat, a sedentary lifestyle, and a higher fat diet. Strength training and even a small percentage of weight loss can meaningfully improve insulin sensitivity here.
As Carol summarized, "I picked these four because they all kind of lead to the same outcome... but from a coaching perspective, I can look at them all through a little bit different lens."
Why This Matters
What struck me most in this conversation is how beautifully designed we are, and how powerful lifestyle medicine truly is. These are principles I teach for addressing many different health concerns, yet they have a real spillover effect into blood sugar and brain health as well.
Knowing your own genetics does not mean you are locked into a certain outcome. It means you can be more specific and more intelligent about where to focus your energy, because as Carol said, we cannot do everything under the sun when it comes to lifestyle changes. Genetics can help us target the interventions that matter most for our own unique biology.
This is part one of a two part conversation with Carol. In part two, we go deeper into what to actually do with your genetic information once you have it, and how that knowledge can help guide your health decisions and protect against cognitive decline and chronic disease over time.
Ready to take a root-cause approach to your health? Start with a free strategy session with the Caring for the Body team.
Whole-person care. Science-backed. Faith-informed.