The Certainty Industry

by Dr. Jordan Shlain

Here’s what I’ve noticed: we’ve turned nutrition into a battleground where confidence matters more than evidence.

Open Instagram, and you’ll find someone declaring with absolute certainty that seed oils are destroying your mitochondria, or that carbs are literally killing you, or that you need to eat like a caveman to unlock your genetic potential.

The tone is never “here’s what the research suggests” or “this worked for me, but your mileage may vary.” It’s always prophetic. Absolute. Revolutionary.

I understand the appeal. Uncertainty is exhausting. 

The idea that your health depends on genetics you didn’t choose, a microbiome you can’t see, and behaviors you struggle to maintain—that’s not a great sales pitch. It’s much easier to hear “just avoid this one thing” or “eat only these foods and everything will change.”

But here’s the reality: when you actually examine the full body of evidence, moderation keeps showing up as the hero. Replacing saturated fats with polyunsaturated fats from vegetable oils? Lowers cardiovascular risk—we’ve known this since the 1970s. Eating diverse plants? Feeds your gut bacteria and reduces inflammation. The Mediterranean diet keeps winning studies not because it’s exotic, but because it’s built on principles that align with how our biology actually works: variety, real food, reasonable portions.

Yet every few years, someone rediscovers the thrill of declaring that everything we thought we knew was wrong. And we believe them, because belief offers something science can’t: belonging. When you say, “I’m keto” or “I’m carnivore,” you’re joining a tribe with clear rules and shared enemies. Science offers probability and nuance. Belief offers identity and certainty.

That’s human, and I get it. But it’s not medicine.

The Optimization Trap

Let me tell you what’s happened to food: it’s become an investment vehicle. Protein bars are now “biohacks.” Ketogenic diets are “metabolic upgrades.” Supplements promise “cellular longevity.” The promise that with the right strategy, you can outperform biology itself.

Walk down any grocery aisle and you’ll see the evidence. Ultra-processed bars and powders wrapped in minimalist fonts and moral vocabulary. “Clean.” “Functional.” “Optimized.” These aren’t food descriptors—they’re branding strategies designed to make you feel sophisticated for eating what is essentially an industrial artifact with a halo.

The NIH actually studied this. They took people and fed them ultra-processed diets versus minimally processed diets, matching everything—calories, macronutrients, even sugar and salt content. The result? People on the ultra-processed diet ate more. Not because they were weak-willed, but because processing itself may affect our satiety. From the paper itself, “Our study was not designed to identify the cause of the observed differences in energy intake.” We don’t know with certainty why ultra-processed ‘food like’ products does this to us.

Meanwhile, the keto boom offers a perfect case study in our hunger for the hack.

Short-term? It works. Appetite suppression, improved glucose control—I’ve seen it. Long-term? It raises LDL cholesterol, disrupts the microbiome, and leads to the same diet fatigue and regression to the mean that every rigid system produces. The data are clear on this. But the narrative—”fat is back, carbs are a conspiracy”—is just more interesting than “it’s complicated.”

We’re drawn to dietary extremes because they feel like rebellion. The carnivore diet is performance art disguised as nutrition: a middle finger to modernity itself. But when you cut out all plant fiber, your gut microbes literally starve. And when they starve, inflammation follows, because your biology isn’t designed for simplicity. Your microbiome wants variety, not a manifesto.

What Actually Compounds

So where’s the real advantage? It’s not hiding in a diet book, influencer post or some exotic superfood. It’s in the patterns that keep proving themselves across populations and decades: eat real food, mostly plants, not too much. Cook at home. Move regularly. Share meals with people you care about.

The Mediterranean diet—rich in fiber, polyphenols, olive oil—keeps winning studies because it feeds both your cells and your bacteria. A one-year trial in older adults showed improved microbial diversity and reduced frailty. Other research found that people with more diverse gut microbiomes simply lived longer.

I know this sounds boring. That’s the point.

In a culture addicted to extremes, balance has become a contrarian position.

This isn’t about perfection or purity. It’s about consistent, unglamorous choices compounded. Small advantages, repeated. The opposite of the hack.

The most radical thing you can do right now might be returning to simplicity. . Common sense, it turns out, might be the actual edge.

Three questions to sit with