According to Gram Research analysis, a large Korean study of 4,085 people identified five distinct lifestyle patterns, with two showing dramatically elevated risk of sudden cardiac arrest: one combining smoking, inactivity, poor sleep, and minimal healthy eating (8.93 times higher risk), and another characterized by very high intake of red meat and fish (15.20 times higher risk). However, the study shows associations only, not proof that these patterns cause heart attacks.
Researchers in South Korea studied over 4,000 people to understand why some people have sudden heart attacks without any warning signs of heart disease. They found that people’s habits—like smoking, exercise, sleep, and what they eat—tend to cluster together in five distinct patterns. Two patterns stood out as being strongly connected to sudden cardiac arrest: one where people eat a lot of red meat and fish, and another combining smoking, no exercise, poor sleep, and eating very little. While this study can’t prove these habits cause heart attacks, it shows that our daily choices work together in ways that might affect heart health.
Key Statistics
A 2026 case-control study of 1,466 cardiac arrest cases and 2,619 controls in South Korea found that people combining smoking, physical inactivity, inadequate sleep, and low healthy food intake had 8.93 times higher odds of sudden cardiac arrest compared to those with balanced lifestyle patterns.
The same 2026 multicentre Korean study identified that individuals with very high reported intake frequency across all food groups, particularly red meat and fish, had 15.20 times higher odds of sudden cardiac arrest compared to the reference group with moderate, balanced dietary patterns.
Researchers analyzing 4,085 South Korean participants discovered five distinct lifestyle phenotypes in 2026, with the two highest-risk patterns showing dramatically different behavioral profiles—one emphasizing dietary excess and another emphasizing multiple simultaneous unhealthy behaviors.
The Quick Take
- What they studied: Whether certain combinations of lifestyle habits (smoking, exercise, sleep, and diet) are connected to sudden cardiac arrest in people without known heart disease
- Who participated: 4,085 people in South Korea: 1,466 who had sudden cardiac arrest and 2,619 healthy community members matched by age, sex, and neighborhood
- Key finding: Five distinct lifestyle patterns emerged, with two showing the strongest connection to sudden cardiac arrest—one involving high meat consumption and another combining smoking, inactivity, poor sleep, and minimal healthy eating
- What it means for you: Your daily habits don’t work in isolation; they cluster together. If you smoke, don’t exercise, sleep poorly, and eat poorly, your risk profile looks very different than someone with just one of these issues. However, this study shows associations, not proof of cause-and-effect.
The Research Details
This was a case-control study, which means researchers compared two groups: people who had experienced sudden cardiac arrest and similar people who hadn’t. They collected data from 2017 to 2023 across multiple hospitals in South Korea. Researchers asked participants about seven lifestyle factors: whether they smoked, how much they exercised, how long they slept, and how often they ate red meat, fish, fruits, and vegetables.
The researchers then used a statistical technique called latent class analysis to find patterns—like grouping people by similar lifestyle combinations rather than looking at each habit separately. This approach is powerful because it recognizes that people’s behaviors cluster together. Someone who smokes is more likely to be inactive and sleep poorly, for example.
They carefully adjusted their analysis to account for other factors that might affect heart attack risk, using a method called directed acyclic graph analysis. This helps ensure the lifestyle patterns themselves—not other confounding factors—are what’s being measured.
Most heart disease risk assessment focuses on individual factors like cholesterol or blood pressure. But this study shows that behavioral patterns matter too, and they matter as clusters. Understanding that unhealthy behaviors tend to occur together helps doctors and researchers see the bigger picture of who might be at risk. This is especially important because many people who have sudden cardiac arrests have no diagnosed heart disease, meaning traditional screening misses them.
This study has several strengths: it’s large (over 4,000 participants), conducted across multiple centers (reducing bias from a single hospital), and used careful statistical methods to account for confounding factors. However, it’s a case-control study, which means it can show associations but not prove causation. The study relied on people’s reported dietary intake, which can be inaccurate. Additionally, all participants were from South Korea, so findings may not apply equally to other populations with different genetic backgrounds or food cultures.
What the Results Show
The analysis identified five distinct lifestyle phenotypes (patterns). The reference group (C2), which showed the lowest rate of sudden cardiac arrest, had a moderate, balanced approach to diet and lifestyle. Compared to this healthiest group, people in other patterns had significantly higher risks.
The two most striking patterns were C4 and C5. Pattern C4 combined smoking, physical inactivity, inadequate sleep (less than 6 hours), and very low intake of healthy foods—this group had an 8.93 times higher odds of sudden cardiac arrest. Pattern C5 was characterized by eating large amounts across all food categories, particularly red meat and fish—this group had a 15.20 times higher odds of sudden cardiac arrest, the highest of all groups.
Patterns C1 and C3 showed moderate increases in risk (1.48 and 1.95 times higher, respectively) compared to the reference group. These patterns likely represented less extreme versions of unhealthy behaviors.
The key insight is that these patterns represent real-world combinations of behaviors that people actually live with, not theoretical combinations. The dramatic differences in risk between groups suggest that how behaviors cluster together matters significantly.
The study revealed that lifestyle patterns are not random—people who smoke tend to be inactive and sleep poorly, and their diet tends to be limited. Similarly, people who eat frequently across all food categories (including high amounts of red meat) form a distinct group. This clustering of behaviors is important because it means interventions targeting one behavior might need to address multiple interconnected habits to be effective.
Previous research has examined individual lifestyle factors and heart disease risk separately. This study advances that work by showing that combinations matter. While earlier studies showed that smoking, inactivity, poor sleep, and poor diet each independently increase heart disease risk, this research demonstrates that when these factors occur together, the risk appears to multiply rather than simply add up. The finding about high red meat consumption is somewhat novel in the sudden cardiac arrest context, though previous research has linked red meat to cardiovascular disease.
This study cannot prove that these lifestyle patterns cause sudden cardiac arrest—it only shows they’re associated with it. People’s memory of their eating habits and exercise may not be perfectly accurate. The study was conducted in South Korea, so results may not apply equally to other countries with different diets, genetics, and healthcare systems. Additionally, the study looked at people who survived to be interviewed; those who died from sudden cardiac arrest weren’t included, which could skew results. Finally, the study cannot determine absolute risk—it only shows relative risk compared to the reference group.
The Bottom Line
Based on this research, maintaining a balanced lifestyle across multiple domains appears protective: moderate physical activity, adequate sleep (7-9 hours), not smoking, and a balanced diet with moderate amounts of fish, fruits, and vegetables. However, these are associations, not proven causes. Confidence level: Moderate. The patterns identified are consistent with existing cardiovascular health guidelines, but this specific study cannot prove these patterns prevent sudden cardiac arrest.
Everyone should care about these findings, but especially people with multiple unhealthy lifestyle factors. If you smoke, don’t exercise, sleep poorly, and eat poorly, this research suggests your risk profile is particularly concerning. People with a family history of sudden cardiac death should pay special attention. However, these findings are not yet ready for individual risk prediction—they’re meant to guide future research and public health approaches.
Lifestyle changes typically show cardiovascular benefits over weeks to months for some markers (like blood pressure and cholesterol), but protection against sudden cardiac arrest may take longer to develop. Consistent adherence to healthy behaviors over years is likely necessary to see meaningful risk reduction.
Frequently Asked Questions
What lifestyle habits are most connected to sudden heart attacks?
Research shows two patterns stand out: smoking combined with inactivity, poor sleep, and minimal healthy eating (8.93x higher risk), and very high consumption of red meat and fish (15.20x higher risk). However, this study shows association, not causation.
Can sudden cardiac arrest happen to people without heart disease?
Yes. This study focused on people without diagnosed cardiovascular disease who experienced sudden cardiac arrest, suggesting conventional risk screening misses many at-risk individuals. Lifestyle patterns may help identify hidden risk.
How quickly can I reduce my sudden cardiac arrest risk by changing habits?
This study cannot determine how quickly risk changes with behavior modification. Cardiovascular benefits from lifestyle changes typically appear over weeks to months for some markers, but protection against sudden cardiac arrest likely requires years of consistent healthy behaviors.
Does eating a lot of fish increase heart attack risk?
In this study, very high intake of fish combined with high red meat consumption was associated with increased risk. Moderate fish consumption is generally considered heart-healthy, suggesting quantity and overall dietary pattern matter more than individual foods.
Should I be worried if I have one unhealthy lifestyle habit?
This study shows that multiple unhealthy habits clustering together pose the greatest risk. Having one unhealthy habit is concerning, but the research suggests the combination of smoking, inactivity, poor sleep, and poor diet together creates particularly elevated risk.
Want to Apply This Research?
- Track the five lifestyle domains together weekly: smoking status (yes/no), minutes of physical activity, hours of sleep, and frequency of red meat, fish, fruit, and vegetable consumption. Create a ’lifestyle pattern score’ that shows whether the user is trending toward healthier or riskier clusters.
- Instead of tackling one habit at a time, help users identify their current lifestyle pattern and suggest simultaneous improvements across multiple domains. For example, if a user is in a high-risk pattern, the app could suggest: ‘This week, add 20 minutes of activity AND aim for 7 hours of sleep AND reduce red meat to 2x per week.’ This addresses the clustering nature of behaviors.
- Monthly pattern reassessment using the same seven indicators. Show users how their combination of behaviors is shifting over time, with visual comparisons to the reference ‘healthiest’ pattern identified in the study. Include motivational messaging that emphasizes how improvements across multiple domains compound.
This research shows associations between lifestyle patterns and sudden cardiac arrest but cannot prove these patterns cause heart attacks. The study was conducted in South Korea and may not apply equally to other populations. These findings are not intended for individual risk prediction. If you have concerns about your heart health or sudden cardiac arrest risk, especially if you have a family history of heart disease or sudden cardiac death, consult with a healthcare provider. This article is for educational purposes and should not replace professional medical advice.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.
