Imagine scrolling through your morning news feed, coffee in hand, feeling good about the 16:8 fasting routine you’ve followed for months. Then a headline stops you cold: intermittent fasting linked to a 91% higher risk of dying from heart disease. Your stomach drops. You set down the coffee. You wonder if the health habit you trusted has been quietly hurting you all along.
That’s exactly what happened to millions of people in March 2024, when a study published in JAMA Internal Medicine made international headlines [JAMA Network]. But as with most things in health science, the real story is far more nuanced than the panic suggested. The alarming statistic obscured important context about study design, missing data, and what fasting research actually tells us.
The Headline That Shocked Everyone
The study analyzed data from more than 20,000 adults drawn from the National Health and Nutrition Examination Survey, tracking eating patterns alongside health outcomes over several years [JAMA Network].
Researchers found that people who ate within an 8-hour window (the hallmark of popular intermittent fasting protocols) had a 91% higher risk of cardiovascular death compared to those eating across 12 to 16 hours [AMA].
The number was staggering. Social media erupted. Fasting influencers scrambled to respond. News outlets ran the story with urgent, alarming framing [CNN]. For anyone who’d embraced time-restricted eating as a path to better health, it felt like the rug had been pulled out.
But a single statistic, stripped from its scientific context, can tell a very misleading story.
What the Study Actually Found
Here’s where things get important.
Photo by This was an observational study, which means researchers watched patterns unfold. They didn’t design an experiment to test whether fasting causes heart problems. As the New York Times noted, the study “shows association, not causation” [New York Times].
The methodology raises further questions. Participants self-reported their eating times through just two days of 24-hour dietary recalls. Those two snapshots were then used to categorize years of eating behavior [Healthline]. Anyone who’s ever had an unusual eating day (a skipped lunch, a late dinner) can see the problem. Two days is a narrow window to define someone’s long-term habits.
Observational designs also can’t fully account for confounding variables. Were participants exercising? Managing stress? Taking medications? These factors shape heart health profoundly, and they weren’t controlled in the way a randomized trial would require.
The Missing Context Everyone Overlooked
Perhaps the most significant gap involves who was eating in those restricted windows and why.
Some participants may have been eating less because they were already sick. People battling chronic illness, depression, or advanced disease often lose appetite and eat during shorter periods. This creates what researchers call reverse causation: the restricted eating didn’t cause poor health outcomes; poor health caused the restricted eating.
The study also didn’t distinguish between someone intentionally practicing intermittent fasting with nutrient-dense meals and someone skipping meals due to poverty, food insecurity, or chaotic work schedules. These are vastly different scenarios with vastly different health implications.
And critically, no data captured what people ate during their windows. An 8-hour eating period filled with processed food tells a completely different metabolic story than one built around whole foods, healthy fats, and lean protein. As Forbes reported, “the findings should be interpreted with caution due to potential confounders” [Forbes].
What Experts Actually Say
Nutrition scientists were quick to push back on the panic.
Photo by Several randomized controlled trials (studies with far more rigorous designs) have shown that intermittent fasting can improve insulin sensitivity, reduce inflammation markers, and support healthy weight management.
These higher-quality studies control for the very variables that observational research cannot. They track what people eat, monitor their health baselines, and compare outcomes against control groups.
That said, experts also acknowledge that fasting isn’t universally safe. People with certain heart conditions, diabetes, eating disorder histories, or those on specific medications may face genuine risks. The conversation isn’t really about whether fasting is good or bad. It’s about whether it’s right for a particular person in their particular circumstances.
Making Sense of Conflicting Research
One study, no matter how large, doesn’t rewrite decades of metabolic research.
Photo by Scientific understanding builds through replication: consistent findings across different high-quality studies using varied methodologies. That’s how consensus forms.
This JAMA study raised worthwhile questions. It reminded the wellness community that no dietary approach is beyond scrutiny, and that’s healthy. But it didn’t prove that intermittent fasting damages hearts.
If you currently practice time-restricted eating and it works well for you, this study alone isn’t a reason to abandon it. If you’re considering starting, it’s worth having a conversation with a healthcare provider who understands your health history, medications, and goals. Personalized guidance will always matter more than headlines.
The March 2024 JAMA study sparked an important conversation, but the full picture looks very different from the alarming headlines. Missing data on participant health, diet quality, and fasting motivations leaves the 91% figure without the context it needs. Current evidence still supports fasting’s benefits when practiced thoughtfully and paired with good nutrition. Science advances through questions, not panic. So the next time a headline shakes your confidence, take a breath, look deeper, and let curiosity guide you rather than fear.
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- JAMA Network Open - Time-Restricted Eating and Cardiovascular Mortality Study 2024
- AMA - 8-hour time-restricted eating patterns and health impacts
- CNN - Time-restricted eating associated with 91% higher cardiovascular death risk
- Healthline - Observational design and self-reported data limitations
- New York Times - Association not causation in observational study design
- Forbes - Findings should be interpreted with caution due to confounders
