Science changes. It’s supposed to. But when you’re standing in a lecture hall in front of two hundred exhausted, caffeine-fueled students, you don't always lead with "this might be wrong in ten years." You teach the curriculum. You teach the boards. Honestly, looking back at the syllabus from a decade ago, it’s a little terrifying how much of what we considered "gold standard" has crumbled under the weight of new data.
The lies I taught in medical school weren't malicious. Nobody was trying to hurt patients. But medicine has a massive momentum problem—it takes an average of 17 years for new clinical research to actually reach the bedside. We were teaching "facts" that had already been debunked in journals because the textbooks hadn't caught up yet.
Think about that. 17 years. That means there are doctors practicing today based on the "certainties" of 2007.
The Great Saturated Fat Boogeyman
For decades, we told students that saturated fat was a direct ticket to a massive coronary event. We drew diagrams of pipes getting clogged with lard. It made sense. It was simple. It was also incredibly oversimplified. We taught the "Diet-Heart Hypothesis" as if it were a law of physics.
The reality? The relationship between dietary fat and heart disease is a messy, tangled web of genetics, metabolic health, and the type of fat involved. Large-scale meta-analyses, like the one published in the Annals of Internal Medicine by Chowdhury et al., started showing that there wasn't a clear link between higher saturated fat consumption and increased risk of heart disease. But we kept teaching the low-fat gospel anyway.
Why? Because if you stop blaming fat, you have to start looking at sugar and processed carbohydrates. That’s a much harder conversation to have with a patient who just wants a pill. We were basically giving people a license to eat "fat-free" snack cakes, which spiked their insulin and probably did more damage to their arteries than a steak ever could.
We Lied About Pain (And Paid For It)
This is the one that keeps me up at night. Back in the late 90s and early 2000s, there was this massive push to treat pain as the "fifth vital sign." We told students that pain was whatever the patient said it was, and that if you treated "real" pain with opioids, the patient wouldn't get addicted.
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We cited a tiny, one-paragraph letter to the editor in the New England Journal of Medicine from 1980—the Porter and Jick letter—as if it were a robust clinical study. It wasn't. It was a brief observation about hospitalized patients, yet it became the cornerstone of a movement that fueled the opioid epidemic. We taught that the risk of addiction was less than 1%.
We were wrong. Dead wrong.
Teaching that pain should always be zero was a lie. Pain is a biological signal. By trying to muffle it entirely with OxyContin and its cousins, we bypassed the body’s warning systems and created a generation of dependency. The nuance was lost. The "lie" was the certainty we projected.
The Myth of the "Chemical Imbalance"
If you’ve ever been treated for depression, you’ve probably heard the "broken thermostat" or "chemical imbalance" analogy. We told students—and they told patients—that depression was simply a lack of serotonin in the brain. Just like a diabetic needs insulin, a depressed person needs an SSRI.
It’s a beautiful, easy-to-understand story. It’s also largely a marketing tool.
A massive umbrella review led by Professor Joanna Moncrieff and published in Molecular Psychiatry in 2022 looked at decades of research and found no consistent evidence that low serotonin levels cause depression. This doesn't mean antidepressants don't work for some people; they clearly do. But the mechanism we taught was a fairytale. Depression is more likely a combination of neuroplasticity issues, systemic inflammation, environmental stressors, and complex neural circuitry. By sticking to the "serotonin lie," we ignored the holistic reality of mental health for a long time.
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Blood Pressure: The Goalposts Keep Shifting
I remember teaching that 140/90 was the "safe" cutoff for blood pressure. Anything below that was fine. Move along.
Then the SPRINT trial came out.
Suddenly, the data showed that for many patients, hitting 120/80 was significantly better for preventing strokes and heart attacks. The "fact" I taught on Tuesday was outdated by Friday. This is the nature of the lies I taught in medical school—they are often just "current best guesses" masquerading as absolute truths. We fail our students when we don't teach them how to be skeptics.
The Body Mass Index (BMI) Delusion
We used BMI as the primary metric for health because it’s easy. It’s math. It’s a ratio.
But BMI was created by a mathematician, Adolphe Quetelet, in the 1830s. He wasn't a doctor. He was looking at populations, not individuals. Yet, we used it to tell fit athletes they were "obese" and to ignore "skinny fat" individuals who had dangerous amounts of visceral fat around their organs. We taught a lie of convenience. We ignored metabolic health markers like waist-to-hip ratio, fasting insulin, and DEXA scans because they took too long or cost too much.
Why Do These Lies Persist?
The medical industrial complex is a slow-moving beast.
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- Insurance Billing: Coding requires specific, rigid diagnoses.
- Pharmaceutical Funding: Research is often funded by those with a vested interest in the "pill for an ill" model.
- The Ego: It is very hard for a senior physician to admit they’ve been giving the wrong advice for thirty years.
I’ve sat in rooms where doctors argued against new guidelines simply because "that's not how we do things here." It’s a culture of tradition that sometimes overrides the culture of evidence.
How to Navigate Your Own Healthcare
Knowing that medical "facts" have an expiration date changes how you should talk to your doctor. You can't just be a passive recipient of information. You have to be a partner.
- Ask "How new is this data?" If your doctor is quoting a guideline, ask if there have been recent updates or dissenting studies.
- Focus on "Outcomes," not just "Numbers." Don't just look at your LDL cholesterol. Ask about your overall risk of a cardiovascular event. Ask about your metabolic health.
- The "Why" Matters. If a doctor suggests a treatment for a "chemical imbalance," ask them to explain the current understanding of that condition beyond the simple analogies.
- Seek Nuance. If a provider is 100% certain about a complex lifestyle issue (like diet or chronic pain), be wary. Real medicine is usually shades of gray.
The most important thing I should have taught my students wasn't a list of facts to memorize. It was a process for thinking. We should have been teaching them how to read a study, how to spot bias, and how to say "I don't know, let's look at the latest evidence together."
The lies I taught in medical school are a reminder that medicine is an evolving practice, not a finished book. Stay curious. Verify everything. Your health depends on it.
Immediate Action Steps for Patients
Stop treating your doctor's word as divine revelation and start treating it as an expert consultation. Next time you're in the office, bring a notebook. Ask about the "NNT" (Number Needed to Treat) for any medication prescribed—this tells you how many people have to take the drug for one person to actually benefit. It’s often a much higher number than you’d think. Also, prioritize "Functional Markers." How do you feel? How is your sleep? How is your grip strength? These are often better predictors of longevity than the outdated metrics still being taught in many lecture halls today.