Chapter 37: From Insulin to Oxytocin -- Love Is Medicine

-- Love Is Medicine

Oxytocin Leadership When we do something we enjoy, we feel pleasure and experience less stress. When we are forced to do something we dislike, the exact same task generates far more strain. But even in unwelcome situations, having some control over when, where, and by when the work needs to be done significantly reduces the burden. The worst-case scenario is doing something you hate, involuntarily, under stress. Add competition with colleagues, and things get even worse. Think of a military-style foot race where soldiers sprint against each other. There is no autonomy, no control. Even when everyone covers the same distance, individual stress levels are wildly different. And even if you win, the person you beat was not an enemy — it was a teammate. Some leaders run their teams this way, pitting people against one another. This is bad leadership. But there are also leaders who operate from cheug-eun-ji-sim — the Confucian concept of compassion that instinctively aches at another's suffering. Instead of saying "Back in my day..." while piling on unreasonable demands, they consider each person's difficulties and lead with genuine empathy. Just knowing that someone trusts you is enough to raise your oxytocin. Leaders should encourage, not surveil. Support, not dictate. Help when things go wrong, not punish. Create the conditions for people to succeed, then step back so they can. Build a culture of mutual care — but let the leader sacrifice first. If someone has to take a hit, it should be the leader. That is oxytocin leadership.

There are two types of diabetes. In type 1, the body cannot produce insulin. In type 2, the issue is not a lack of insulin but a failure of insulin to work properly — a condition called insulin resistance, typically driven by obesity and inactivity. Our cells need energy to function, and they get it from carbohydrates, fats, and proteins. For cells to absorb glucose — the body's primary carbohydrate fuel — they need the hormone insulin. In type 1 diabetes, without insulin to help, glucose piles up in the bloodstream instead of entering cells. Blood sugar skyrockets, the body wastes away for lack of fuel, and death eventually follows. In 1923, Frederick Banting and Charles Best solved this by isolating insulin from dogs and making it usable for humans, a breakthrough that earned them the Nobel Prize in Medicine. But insulin from that era, extracted mainly from animal pancreases, was hard to produce in large quantities and did not last long. A better solution was needed.

From Insulin Research to Discovering Oxytocin

In 1923, a twenty-two-year-old chemistry student named Vincent du Vigneaud heard about the discovery of insulin from Professor Johnstone Rose, who had just returned from meeting Banting and Best. Deeply impressed, du Vigneaud threw himself into insulin research. His original interests lay in insulin synthesis and in the amino acid cysteine and its disulfide bonds, but over time he shifted his attention to a much smaller molecule: oxytocin. What started as insulin research led him to synthesize oxytocin — the first peptide hormone ever created by human hands — earning him the 1955 Nobel Prize in Chemistry.* Once synthetic oxytocin became available for injection, doctors could assist mothers in labor and save countless lives of both mothers and newborns.¹

\* Most hormones in the body fall into two categories: peptide hormones (like oxytocin and insulin) and steroid hormones (like the sex hormones).

My own work is not remotely comparable to du Vigneaud's, but I too have traveled a path from insulin to oxytocin. In 1995, I started a master's degree at the University of Alberta in Canada, focusing on diabetes and insulin resistance. I studied why people with spinal cord injuries — who face three to five times the normal diabetes risk — develop the disease at such high rates, and I conducted the first studies measuring their capacity for insulin production and secretion. I was part of the team for Dr. Edmond Ryan's first successful islet cell transplantation — a technique that allowed type 1 diabetes patients to live free of insulin injections by receiving transplanted beta cells rather than an entire pancreas. I developed exercise-based tests to measure insulin secretion in spinal cord injury patients before and after physical activity. During my doctoral work, I expanded from insulin to leptin, the hormone involved in regulating obesity. At Harvard, my postdoctoral research explored how leptin acts on cells throughout the body via the brain and the autonomic nervous system. After joining the faculty at Yonsei University in 2005, I pursued a wide range of studies on obesity, insulin resistance, and exercise in partnership with Severance Hospital.²

Knocking on Death's Door — and Finding Oxytocin

Then came an ordinary day in 2009 that turned out to be anything but ordinary. While teaching a class on therapeutic recreation, I said something completely off the cuff: "Would a cancer patient with six months to live have better quality of life spending that time doing things they enjoy, rather than lying in a hospital bed hooked up to IVs, waiting to die?" The words were barely out of my mouth when a second thought hit me: What if living more joyfully also meant living longer? It was pure improvisation — an idea I had not planned at all.

But I had talked myself into it. I hurried to the lab and typed three keywords into a medical database: exercise, cancer, mortality. The results poured in. Breast cancer patients who walked three hours per week cut their recurrence in half. Colon cancer patients who walked six hours per week halved theirs. I shouted "Eureka!" in my head. Exercise really is the best medicine. Exercise really is the ultimate prevention.³

Then another question surfaced: Why does exercise cut cancer recurrence in half? Obese patients have higher cancer incidence and recurrence, and the underlying mechanisms closely resemble those by which obesity drives diabetes. And remarkably, those same mechanisms overlapped with the pathways through which exercise improves diabetes. I slapped my knee. This was my research to do. From 2011 to 2012, I returned to Harvard as a visiting professor to study cancer and exercise, and I have been at it ever since. I demonstrated that exercise accelerates recovery after colon cancer surgery, restores upper-limb function in breast cancer patients within a month, and resolves the bowel dysfunction that plagues rectal cancer survivors — all verified through rigorous clinical trials and documented across more than a hundred published papers. In particular, I established that exercise's improvement of insulin resistance plays a central role in preventing cancer recurrence. Cancer was far from my only focus: I also conducted research on spinal cord injury patients, cardiac rehabilitation patients, and people with Parkinson's disease, diabetes, obesity, and pediatric epilepsy.

If I had to summarize my research in a single sentence, it would be this: I test whether exercise is medicine. I then design optimal exercise programs for specific conditions, validate their effectiveness, and turn them into formats anyone can use on their own. Today, as a professor in Yonsei University's Department of Sport and Leisure Studies — with concurrent positions at Severance Cancer Hospital's Cancer Prevention Center and the Graduate School of Artificial Intelligence — I have come to see something I once overlooked: who you exercise with and when you exercise matter just as much as the type of exercise. The reason is oxytocin. Oxytocin rises when we move together, not alone. If the exercise involves physical touch, even better. If it involves looking into each other's eyes and cooperating, better still.

In 2020, Larry Young, one of the world's leading authorities on oxytocin, quoted Karl Menninger in a major paper: "Love is medicine. It is medicine for both the one who gives it and the one who receives it." Young wrote that if Menninger were alive today, he would embrace the growing body of evidence connecting oxytocin to disease prevention and recovery. He was right. Exercise is medicine. But there is something even more powerful: love. And oxytocin is the proof. My hope for every reader of this book is straightforward — raise your oxytocin through the oxytocin lifestyle, meet more people, become happier. Could this be exactly what Menninger was reaching for when he urged us to embrace the life instinct of love and let go of hatred?

Oxytocin in Action: Reflective travel is best done alone, but travel that boosts oxytocin needs to be shared with the people who matter most to you. Think about it: eating delicious food together, exercising together, gossiping, making eye contact, doing fun things as a group — it is the entire oxytocin lifestyle rolled into one activity. That activity is traveling with someone you love.