As an internist with a background in physics, I was taught to think in systems—to seek root causes, avoid assumptions, and apply data with precision. Early in my career, I practiced medicine exactly as I had been trained: Identify the diagnosis, follow the algorithm, apply evidence-based treatment. And in many cases, that worked.

But increasingly, I found myself caring for patients who didn’t fit cleanly into diagnostic boxes. Fatigue, brain fog, digestive issues, anxiety, chronic pain, metabolic instability—patients who had “normal” labs, had seen multiple specialists, and were still unwell.

As someone with expertise in eating disorders, I was already attuned to how profoundly the body, mind, and environment intersect. These patients taught me the same lesson again: that illness is rarely confined to one system, and healing rarely comes from a single intervention.

That’s what drew me to functional medicine—not as an alternative, but as a return to foundational clinical reasoning.

Functional medicine is often misunderstood as fringe or unscientific. In reality, it is a systems-based, evidence-informed clinical model focused on identifying and addressing the root causes of dysfunction. It considers how nutrition, sleep, stress, environmental exposures, life experiences, and genetics all interact to shape health.

These principles aren’t foreign to conventional medicine. They’re just rarely integrated.

Instead of asking only, “What is the diagnosis?” functional medicine also asks, “Why did this happen?” and “What’s keeping this person from healing?”

This mindset is especially relevant in eating disorders, where patients experience disruptions across every major system—neuroendocrine, gastrointestinal, cardiovascular, and psychiatric. Even after behavioral symptoms improve, physiological recovery is often incomplete unless we address the deeper layers: nutrient depletion, microbial imbalance, HPA-axis dysregulation, and trauma physiology.

Functional medicine reminds us that we have the tools to assess and intervene at that level. Doctors learn them in medical school and they get lost in the time crunch of clinical practice.

Conventional care is optimized for acute, single-system disease. But for patients with complex, overlapping symptoms—many of whom have been labeled “somatic,” “functional,” or “treatment-resistant”—the standard approach often falls short.

Functional medicine steps into that gap by asking broader, integrative questions:

• Is chronic inflammation playing a role in this person’s mood symptoms or fatigue?
• How is gut health influencing cognition, immune function, or anxiety?
• Are nutrient imbalances or metabolic instability impairing endocrine function?
• What environmental or psychosocial stressors are dysregulating the body’s adaptive systems?

These aren’t speculative questions—they are grounded in physiology, and increasingly supported by literature across immunology, neurology, endocrinology, and nutrition science.

More tools, not fewer

I still practice conventional medicine. I prescribe medications, refer to specialists, and value evidence-based guidelines. But functional medicine has given me more tools—and more ways to meet patients where the standard playbook fails.

Sometimes the intervention is simple: magnesium to support sleep, an anti-inflammatory nutrition plan, identification of food intolerances, or circadian realignment. Other times, it’s testing for underlying infections, assessing toxic exposures, or supporting mitochondrial function.

What unites these approaches is a return to the clinical basics: listen closely, think systemically, and treat the person, not just the protocol.

Patients with eating disorders taught me early in my career how easily the most vulnerable can be dismissed. When symptoms don’t respond as expected, it’s tempting to assume the problem is psychological—or not real.

Functional medicine challenges that assumption. It honors the complexity of chronic illness, and brings back the idea that healing isn’t about finding the perfect label—it’s about understanding the full context of the person in front of us.

This model isn’t perfect, and it’s not always easy to implement. But it’s deeply aligned with good medicine. For many of our sickest patients, it may be the first time someone has truly connected the dots.

And often, that’s where healing begins.

Sally Daganzo is an internal medicine physician.