A 2026 cross-sectional study of 891 Portuguese adults found that people who regularly use screens are 2.36 times more likely to eat unhealthily, while non-smokers are 79% less likely to have poor diets. According to Gram Research analysis, these findings suggest unhealthy lifestyle behaviors cluster together, indicating that integrated public health approaches addressing multiple habits simultaneously may be more effective than isolated interventions.
A new study of 891 Portuguese adults reveals surprising connections between lifestyle habits and diet quality. Researchers found that people who spend lots of time on screens are more than twice as likely to eat unhealthily, while non-smokers are much less likely to have poor diets. According to Gram Research analysis, these findings suggest that unhealthy behaviors often cluster together—meaning if you’re struggling with one bad habit, you might be struggling with others too. The study highlights why public health efforts need to address multiple lifestyle issues at once rather than tackling diet alone.
Key Statistics
A 2026 cross-sectional study of 891 Portuguese adults found that screen users were 2.36 times more likely to have unhealthy diets compared to those with minimal screen time, according to weighted logistic regression analysis.
In the same 2026 Portuguese population study, non-smokers had 79% lower odds of unhealthy diet compared to smokers (odds ratio = 0.21), suggesting smoking status is strongly associated with overall dietary quality.
The 2026 Portuguese diet study showed moderate predictive ability (AUC = 0.62) for identifying unhealthy diet based on lifestyle factors, indicating that screen time and smoking explain only part of the variation in eating habits.
The Quick Take
- What they studied: What lifestyle habits are connected to eating unhealthily among Portuguese adults, and which ones are the strongest predictors?
- Who participated: 891 Portuguese adults from a nationwide survey conducted in 2019, representing a cross-section of the general population
- Key finding: People who use screens frequently are 2.36 times more likely to eat unhealthily, while non-smokers are 79% less likely to have poor diets
- What it means for you: If you’re spending excessive time on screens or smoking, you may want to examine your eating habits too. These behaviors often go hand-in-hand, so improving one area might help improve others. However, this study shows correlation, not that one causes the other.
The Research Details
Researchers surveyed 891 Portuguese adults in 2019 and asked them detailed questions about their eating habits, screen time, smoking status, and other lifestyle factors. They defined a healthy diet as eating regular meals, consuming adequate fruits and vegetables, and drinking alcohol moderately—all based on official health guidelines. Using statistical analysis called logistic regression, they identified which lifestyle factors were most strongly connected to unhealthy eating patterns.
The researchers weighted their data to make sure the sample accurately represented the Portuguese population. This approach allowed them to identify independent associations—meaning they could determine which factors mattered most even when multiple factors were present. The study was designed as a snapshot in time rather than following people over years, which is why it’s called cross-sectional.
Understanding which lifestyle behaviors cluster together helps public health officials design better intervention programs. Rather than creating separate campaigns for diet, smoking, and screen time, this research suggests integrated approaches addressing multiple behaviors simultaneously might be more effective. The findings also highlight that people’s perception of their diet quality may not match reality—many Portuguese adults thought their diets were healthier than they actually were.
The study used a population-based sample, which is stronger than convenience samples. However, the statistical model showed only moderate ability to predict unhealthy diet (AUC = 0.62), meaning other unmeasured factors also influence eating habits. The study is observational, so it identifies associations but cannot prove that screen time or smoking directly causes unhealthy eating. The cross-sectional design captures only one moment in time, not how behaviors change over years.
What the Results Show
The most striking finding was the strong association between screen use and unhealthy diet. Adults who regularly used screens were 2.36 times more likely to eat unhealthily compared to those with minimal screen time. This remained true even after accounting for other factors like smoking status and demographic characteristics.
The second major finding involved smoking. Non-smokers were significantly less likely to have unhealthy diets, with the odds reduced by 79% (odds ratio = 0.21). This suggests that people who don’t smoke may be more generally health-conscious or have better overall lifestyle habits.
Interestingly, the statistical model could only moderately predict unhealthy diet (AUC = 0.62 on a scale where 1.0 is perfect prediction). This means that while screen time and smoking are important factors, many other influences on diet quality weren’t captured in this study—such as income, education, food availability, cultural factors, and personal preferences.
The study revealed that Portuguese adults tend to overestimate how healthy their diets are. This perception gap is important because people who think they’re eating well may not feel motivated to make changes. The research also suggests that unhealthy behaviors cluster together—people with one unhealthy habit often have others, indicating that lifestyle interventions should address multiple behaviors simultaneously rather than in isolation.
This research aligns with existing studies showing connections between sedentary behavior (like screen time) and poor diet quality. Previous research has also documented that smoking is associated with other unhealthy behaviors. However, this Portuguese study provides specific quantitative evidence for these associations in a European population and emphasizes the importance of integrated public health approaches. The finding about overestimating diet healthfulness echoes similar research in other countries.
The study captures only one moment in time, so we can’t determine whether screen time causes unhealthy eating or if unhealthy eating leads to more screen time. The statistical model’s moderate predictive ability (AUC = 0.62) means important factors are missing—possibly income, education, food access, or cultural influences. The study is limited to Portuguese adults, so findings may not apply equally to other populations. Additionally, the study relied on self-reported data, which can be inaccurate when people underestimate screen time or overestimate healthy eating.
The Bottom Line
If you spend significant time on screens, consider this a signal to examine your overall lifestyle habits, particularly your diet. Try reducing screen time gradually and replacing it with activities like meal preparation or physical activity. For smokers, quitting smoking may be part of a broader lifestyle improvement that includes better eating habits. Public health officials should develop integrated programs addressing multiple unhealthy behaviors rather than isolated campaigns. Confidence level: Moderate—the associations are clear, but causation isn’t proven.
Anyone concerned about their diet quality should pay attention, especially if they also spend substantial time on screens or smoke. Parents should note the screen-time connection when thinking about their children’s eating habits. Public health officials and healthcare providers should use these findings to design more comprehensive lifestyle intervention programs. People who think their diet is healthier than it probably is should take particular note.
Changes in eating habits typically take 2-4 weeks to become noticeable and 8-12 weeks to become established as new routines. If you’re also reducing screen time, you may see improvements in diet quality within a few weeks as you have more time for meal preparation and mindful eating. However, sustainable lifestyle change usually requires 3-6 months of consistent effort.
Frequently Asked Questions
Does spending too much time on screens actually cause people to eat worse?
This study shows a strong association—screen users are 2.36 times more likely to eat unhealthily—but doesn’t prove screens cause bad eating. The connection could work both ways, or other factors might influence both behaviors. More research is needed to determine causation.
Why are smokers more likely to have unhealthy diets?
The study doesn’t explain why, only that the connection exists. Smokers may be less health-conscious overall, have different stress-management approaches, or face different social influences. Non-smokers showed 79% lower odds of unhealthy eating in this Portuguese population.
Can improving my diet help me quit smoking or reduce screen time?
This study shows these behaviors cluster together but doesn’t prove improving one helps the other. However, addressing multiple unhealthy habits simultaneously through integrated programs may be more effective than tackling them separately, according to the researchers’ recommendations.
How accurate is this study for predicting who eats unhealthily?
The study’s statistical model showed moderate accuracy (AUC = 0.62), meaning screen time and smoking alone can’t reliably predict diet quality. Income, education, food access, and cultural factors likely play important roles too.
Should I be concerned if I use screens a lot and eat poorly?
Yes, this research suggests these behaviors often occur together. Consider examining your overall lifestyle habits and making gradual changes. Start with one specific goal—like a screen-free meal daily—rather than trying to change everything at once.
Want to Apply This Research?
- Track daily screen time (hours per day) alongside meal quality scores. Create a simple daily log: rate each meal as ‘healthy’ (includes vegetables, whole grains, moderate portions) or ‘unhealthy,’ then note total screen hours. Look for patterns over 2-week periods to see if reducing screen time correlates with better meal choices.
- Set a specific ‘screen-free meal’ goal—commit to eating at least one meal daily without phones, tablets, or TV. Use the app to set reminders for this meal and track completion. This single change addresses both screen time and eating quality simultaneously, aligning with the research showing these behaviors are connected.
- Create a weekly dashboard showing: (1) average daily screen hours, (2) percentage of meals rated as healthy, and (3) a combined ’lifestyle score.’ Track these metrics weekly for 12 weeks to establish baseline patterns, then set incremental reduction goals for screen time while monitoring corresponding improvements in diet quality.
This study identifies associations between lifestyle factors and diet quality but does not prove causation. Results are based on Portuguese adults and may not apply equally to other populations. The study relied on self-reported data, which can be inaccurate. If you have concerns about your diet or health, consult with a healthcare provider or registered dietitian for personalized advice. This research should not replace professional medical guidance.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.