How to Stop Falling for Terrible Nutrition Studies (And Why They Keep Getting Published)
A practical guide to not being fooled by sciencey-sounding nonsense
Last week, my social media feed exploded with headlines about a "groundbreaking study" showing that people who skip breakfast have higher rates of diabetes. The articles were breathless: "Scientists Prove Breakfast Prevents Diabetes!" and "Skipping Breakfast Could Kill You!"
I clicked through to the actual study. It was garbage.
Not because the researchers were incompetent or malicious, but because it was the wrong type of study to answer the question everyone was asking. Yet here it was, being treated as definitive proof and spawning a thousand more "breakfast is essential" articles.
This happens constantly in nutrition science, and it's creating a world where we're drowning in contradictory dietary advice based on fundamentally flawed research. Let me teach you how to spot these studies so you don't get fooled again.
The Hierarchy of Evidence: Not All Studies Are Created Equal
Think of scientific evidence like a pyramid. At the bottom, you have weak evidence that can only suggest possible connections. At the top, you have strong evidence that can actually prove cause and effect.
Bottom Tier: Observational Studies
Cross-sectional studies (snapshot of people at one moment)
Case-control studies (comparing groups after the fact)
Cohort studies (following groups over time)
Top Tier: Experimental Studies
Randomized controlled trials (RCTs)
Meta-analyses of RCTs
Here's the crucial difference: Observational studies can only show correlation. Experimental studies can prove causation.
The Breakfast Study That Fooled Everyone
Let's dissect that diabetes study as an example. Researchers looked at Japanese teenagers and found that those who skipped breakfast were more likely to have prediabetes. The media interpreted this as "skipping breakfast causes diabetes."
But this was a cross-sectional observational study. Here's what that actually tells us:
At one point in time, some teenagers skipped breakfast
At that same point in time, some teenagers had prediabetes
These two things occurred together more often than expected by chance
What it doesn't tell us:
Whether skipping breakfast caused the prediabetes
Whether having prediabetes caused breakfast skipping
Whether both were caused by some third factor entirely
Think about it logically: What kind of teenager skips breakfast? Probably one who:
Stays up late and sleeps in
Has poor family structure or supervision
Makes impulsive food choices throughout the day
Has irregular sleep patterns
Lives in a chaotic household environment
Any of these factors could contribute to prediabetes. The study found a correlation, but correlation is not causation.
The Red Flags to Watch For
1. Headline Claims vs. Study Design If the headline says "X causes Y" but the study just observed people, you're being misled. Observational studies cannot prove causation, period.
Red flag phrases:
"Study shows X causes Y"
"Research proves..."
"Scientists discover X prevents Y"
What observational studies can actually say:
"X is associated with Y"
"People who do X are more likely to experience Y"
"X and Y appear to be connected"
2. Lifestyle Clustering Most health behaviors cluster together. People who eat breakfast regularly also tend to:
Exercise more
Sleep better
Have higher incomes
Plan their meals
Follow other healthy habits
When a study finds that "breakfast eaters are healthier," it's probably measuring this entire cluster of behaviors, not breakfast specifically.
3. Self-Reported Data Many nutrition studies rely on people accurately remembering and reporting what they ate weeks or months ago. Spoiler alert: people are terrible at this.
Studies show people consistently:
Under-report calories by 20-40%
Over-report healthy foods
Under-report unhealthy foods
Forget snacks and drinks
4. Relative Risk vs. Absolute Risk Headlines love to trumpet scary-sounding numbers like "50% increased risk!" But context matters enormously.
If a disease affects 2 out of 100,000 people normally, and some behavior increases that to 3 out of 100,000 people, that's a "50% increased risk" but an absolute increase of just 0.001%. The relative risk sounds terrifying; the absolute risk is negligible.
The Gold Standard: Randomized Controlled Trials
When researchers actually want to test whether breakfast matters, they do something completely different. They take similar groups of people and randomly assign some to eat breakfast and others to skip it. Then they measure what happens.
When this has been done with breakfast, the results are clear: eating breakfast doesn't provide the magical benefits claimed by observational studies. No significant differences in weight loss, metabolism, or health markers.
Why RCTs are better:
Random assignment eliminates lifestyle clustering
Researchers control the intervention
They can prove causation, not just correlation
Why we don't see more RCTs:
They're expensive (often millions of dollars)
They take years to complete
They often show boring, null results
They're harder to publish and get media attention
The Broken Incentive System
Here's the dirty secret: the scientific publishing system is fundamentally broken when it comes to nutrition research.
Researchers face "publish or perish" pressure. Their careers depend on getting studies published, and observational studies are:
Cheap to conduct
Quick to complete
Easy to get "positive" results from
More likely to be published than boring null results
Journals prefer exciting findings. "Breakfast prevents diabetes!" gets more attention than "We found no significant relationship between breakfast and diabetes."
Media amplifies weak findings. Science journalists often don't understand the difference between observational and experimental studies, so they report correlations as if they prove causation.
Food companies fund convenient research. Cereal companies love observational studies showing breakfast eaters are healthier. They don't fund RCTs that might disprove their marketing claims.
The result? We're drowning in weak observational studies while rigorous experimental research gets less attention and funding.
How to Protect Yourself
1. Look for the study design Before believing any nutrition headline, find the actual study and check:
Was it observational or experimental?
How many people were involved?
How long did it last?
Who funded it?
2. Ask the right questions
Could this just be lifestyle clustering?
Are they measuring correlation or causation?
What's the absolute risk, not just relative risk?
Does this contradict well-designed RCTs?
3. Be especially skeptical of:
Single studies making big claims
Research that confirms what food companies want to hear
Headlines that claim to "prove" anything from observational data
Studies based entirely on self-reported dietary data
4. Look for consistency in RCTs Real nutritional insights come from multiple well-designed randomized controlled trials showing consistent results. If the RCTs contradict the observational studies, trust the RCTs.
The Breakfast Example: How Science Should Work
Let's trace how the breakfast story should have unfolded:
Observational studies in the 1960s-90s showed breakfast eaters were healthier
Hypothesis formed: Maybe breakfast improves health
RCTs conducted in the 2000s-2010s to test this hypothesis
Results: No significant benefits from breakfast when properly tested
Conclusion: The observational studies were measuring lifestyle patterns, not breakfast effects
Instead, what happened was:
Observational studies showed correlation
Media and industry treated this as proof of causation
Decades of marketing built an entire mythology around breakfast
RCTs eventually disproved the claims
But the mythology persists because it serves commercial interests
The Bottom Line
Most nutrition headlines are based on weak observational research that can't prove what the headlines claim. These studies aren't useless—they can suggest interesting hypotheses for future research—but they shouldn't guide your food choices.
The next time you see a nutrition headline, ask yourself:
Is this based on an observational study or an RCT?
Could lifestyle clustering explain these results?
Does this contradict stronger experimental evidence?
Who benefits if people believe this claim?
Your ability to spot weak studies is your defense against a broken system that churns out misleading nutrition advice. Don't let observational studies masquerading as definitive proof dictate what you eat.
The goal isn't to become cynical about all research, but to become appropriately skeptical about weak research. When multiple well-designed RCTs consistently show the same result, that's worth paying attention to. When a single observational study gets breathless media coverage, that's worth ignoring.
Your health decisions deserve better evidence than correlation dressed up as causation.
Want to dive deeper into how nutrition myths are created and perpetuated? Look for my upcoming book "We're Not Sick, We're Being Sold.", where I trace the marketing origins of our most persistent dietary dogmas and teach you to distinguish between science and salesmanship.
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