How Bad Science Twists the Truth About Low-Carb Diets
From candy bars to cardiology journals, this is how bad science and sensational headlines distort low-carb diets—and what you need to know to cut through the noise.
What if you could live on a diet of Reese’s Peanut Butter Cups, lose body fat, and improve your health?
It sounds absurd—and it is.
But the absurdity of that thought experiment highlights a persistent misunderstanding about ketogenic and low-carb diets.
Now, I promise, we’ll get back to Reese’s. But first I want to unwrap the real theme of this letter.
When you think “low-carb” or “keto,” what comes to mind?
For many people, it’s the sizzle of bacon, the melt of butter. But right behind that indulgent image lurks a negative gut reaction: clogged arteries, heart attacks, strokes.
Why?
Because for most, the perception isn’t based on evidence—it’s a feeling.
As a metabolism scientist, I like to explore the intersection of “the science” and the psyche.
So today, we’ll walk through a series of four examples showing how media and science can bend reality—sometimes so far that they’d have you believe a Reese’s Peanut Butter Cup counts as “low-carb.”
Study 1: Skews the Truth with “Scores”
Take as our first example, recent study that was touted as “proof” online that low-carbohydrate diets don’t help—or can even exacerbate—diabetes.
At first, the headlines seem compelling, if for no other reason than the American Diabetes Association “seal of approval.”
But what did the researchers actually measure?
And what did they call “low-carb?”
This was a nutritional epidemiology study based on food-frequency questionnaires. Participants self-reported their diets, and researchers divided them into quintiles (fifths) according to carbohydrate intake. They then assigned each group a “low-carbohydrate score” relative to the others.
Here’s the problem…
The lowest-carb group across multiple cohorts was still eating ~40% of calories from carbohydrates.
That’s not low-carb—it’s about the same carb proportion you’d find in a Reese’s Peanut Butter Cup.
Low-carbohydrate diets are typically <20% of calories from carbs.
Ketogenic diets are typically <5% of calories from carbs.
To suggest that a 40% carbohydrate intake reflects a “low-carb” diet is not just sloppy—it misleads the public and obscures the evidence showing that carbohydrate restriction is effective for both type 1 and type 2 diabetes.
But that’s just the beginning. The headlines around “low-carb failure” aren’t accidents—they’re part of a larger pattern. And the deeper you look, the worse it gets.
In the rest of this letter, I’ll take you through:
Study 2: Science Advances, Soybean Oil, & ‘Squeaks’
Study 3: “Worse than Useless” — How a fatally flawed ward trial became “truth.”
Study 4: The Worst Title Ever Published in Cardiology
Practical Guide to Spot Misinformation: Finally, I’ll give you a simple checklist to spot future falsehoods before they fool you.
If you want the curtain pulled back—or just ammo for your next friends-and-family debate—this is where the rubber meets the road…
