Shift workers in Iran eat significantly more unhealthy processed foods than regular daytime workers, according to a Gram Research analysis of 3,158 workers. Shift workers consumed 212 grams of processed foods daily compared to 180 grams for regular workers, and drank 23 grams more soft drinks per day. The study suggests that irregular work schedules make it harder to maintain healthy eating habits, particularly for drivers working shifts.
A Gram Research analysis of over 3,000 Iranian workers found that people working night shifts eat significantly more unhealthy foods than those working regular daytime hours. Shift workers consumed about 32 grams more processed foods daily, drank more soft drinks, and ate more high-fat dairy products. The study suggests that irregular work schedules make it harder for people to maintain healthy eating habits. Researchers believe workplaces should offer better food options and nutrition support for shift workers to help them make healthier choices despite their challenging schedules.
Key Statistics
A 2026 cross-sectional study of 3,158 Iranian workers found that shift workers consumed 32 grams more processed foods daily (212g vs. 180g) compared to regular daytime workers.
According to research reviewed by Gram, shift workers drank significantly more soft drinks, averaging 121 grams per day versus 98.2 grams daily for non-shift workers—a 23-gram daily difference.
A 2026 analysis of 3,158 workers in Iran found that 16.8% worked shifts, and these shift workers consumed 46.3 grams of high-fat dairy products daily compared to 39.2 grams for regular workers.
Shift workers in the Shahedieh cohort study showed the strongest associations with unhealthy eating when their jobs involved driving, such as truck drivers or delivery drivers.
The Quick Take
- What they studied: Whether people who work night shifts or rotating shifts eat differently than people who work regular daytime hours
- Who participated: 3,158 male workers in Iran, including 530 shift workers and 2,628 regular daytime workers. Data was collected between 2015 and 2017
- Key finding: Shift workers ate about 32 grams more processed food per day and drank significantly more soft drinks (121 grams vs. 98 grams daily) compared to regular workers
- What it means for you: If you work night shifts or rotating schedules, you may need to be extra intentional about eating healthy foods. Planning meals ahead and having nutritious snacks available can help counter the tendency to reach for convenient junk food during odd hours
The Research Details
Researchers looked at information collected from workers in Yazd, Iran between 2015 and 2017. They compared what shift workers ate to what regular daytime workers ate using detailed food questionnaires. The study captured information about work schedules, age, income, and lifestyle habits. This type of study (called cross-sectional) takes a snapshot in time rather than following people over many years, so it shows associations but not necessarily cause-and-effect relationships.
The researchers used a validated food frequency questionnaire, which is a reliable tool that asks people to report how often they eat different foods. They then calculated average daily intake of various food categories, paying special attention to processed and ultra-processed foods like snacks, soft drinks, and high-fat dairy products. They adjusted their analysis to account for factors like age and job type that might influence eating patterns.
Understanding how work schedules affect eating habits is important because shift work is common worldwide, affecting millions of people. If shift workers consistently eat less healthy diets, this could contribute to higher rates of obesity, diabetes, and heart disease in this population. This research helps identify a specific problem so that workplaces and health organizations can develop targeted solutions.
This study has several strengths: it included a large number of participants (over 3,000), used a validated food questionnaire, and collected detailed information about work schedules and other factors. However, because it’s cross-sectional, it only shows a snapshot in time and cannot prove that shift work causes unhealthy eating—only that the two are associated. The study focused only on male workers in Iran, so results may not apply equally to women or people in other countries with different food cultures and work environments
What the Results Show
Shift workers reported eating significantly more unhealthy foods compared to regular daytime workers. On average, shift workers consumed 46.3 grams of high-fat dairy products daily versus 39.2 grams for regular workers—a difference of about 7 grams per day. They also consumed more snacks (1.50 grams vs. 1.07 grams daily) and notably more soft drinks (121 grams vs. 98.2 grams daily). Most striking was the total processed food intake: shift workers averaged 212 grams per day compared to 180 grams for regular workers, a 32-gram daily difference.
Interestingly, shift workers actually ate less pizza than regular workers, and they had different meal frequency patterns. This suggests that shift work doesn’t simply lead to eating more of everything—instead, it changes what types of foods people choose and when they eat.
The differences were especially pronounced among shift workers whose jobs involved driving, such as truck drivers or delivery drivers. These workers showed the strongest associations with high soft drink and processed food consumption. The researchers also found that age played a role: the relationship between shift work and unhealthy eating was stronger in some age groups than others.
The study found that different types of shift workers had different eating patterns. Drivers who worked shifts showed the strongest associations with unhealthy eating, suggesting that the combination of shift work plus a job that involves driving may create additional barriers to healthy eating. The researchers also noted that meal frequency patterns differed between groups, indicating that shift workers may be eating at different times of day or in different patterns than regular workers, which could affect their food choices.
Previous research has suggested that shift work disrupts normal eating patterns and circadian rhythms (the body’s natural 24-hour cycle), but most studies have focused on developed countries. This study is valuable because it provides evidence from a Middle Eastern population, where food cultures and work environments differ from Western countries. The findings align with existing research showing that irregular work schedules make it harder to maintain healthy eating habits, but this study provides specific numbers for a population that hadn’t been well-studied before.
This study has important limitations to consider. First, it only included male workers, so we don’t know if the same patterns apply to women. Second, it was conducted in Iran, so the results may not apply to other countries with different food availability and work cultures. Third, because it’s a snapshot in time rather than following people over years, we can’t be certain that shift work causes unhealthy eating—only that shift workers tend to eat less healthily. Fourth, the study relied on people’s memories of what they ate, which can be inaccurate. Finally, the study didn’t measure actual health outcomes like weight gain or disease, only food intake
The Bottom Line
If you work night shifts or rotating schedules, consider these evidence-based strategies: (1) Plan and prepare meals ahead of time so you have healthy options available during odd hours, (2) Keep nutritious snacks like nuts, fruit, and yogurt accessible at work, (3) Limit soft drinks and sugary beverages by keeping water and unsweetened drinks available, (4) Try to maintain regular meal times even when your work schedule changes. Employers should consider providing healthy food options in break rooms and educating shift workers about nutrition. These recommendations are supported by moderate evidence from this and similar studies
This research is most relevant to people who work night shifts, rotating shifts, or irregular schedules—including healthcare workers, factory workers, security guards, truck drivers, and others in shift-based jobs. It’s also important for employers, occupational health professionals, and policymakers who want to support worker health. If you work regular daytime hours, this research suggests you may have an easier time maintaining healthy eating habits, though the principles still apply
Changes in eating habits don’t happen overnight. If you implement healthier eating strategies, you might notice improvements in energy levels within 2-4 weeks and more significant health changes within 2-3 months. However, maintaining these changes requires ongoing effort, especially when working irregular schedules
Frequently Asked Questions
Do shift workers eat unhealthier than regular workers?
Research shows shift workers eat significantly more processed foods and soft drinks. A study of 3,158 Iranian workers found shift workers consumed 32 grams more processed food daily and drank 23 grams more soft drinks than regular daytime workers.
Why do night shift workers eat more junk food?
Shift work disrupts normal eating patterns and makes it harder to access healthy food options during odd hours. Irregular schedules also affect the body’s natural hunger signals, making people more likely to reach for convenient processed foods and sugary drinks.
What can shift workers do to eat healthier?
Plan meals ahead, keep nutritious snacks at work, limit soft drinks, and try to maintain regular meal times despite schedule changes. Having healthy options readily available makes it easier to avoid vending machine snacks and processed foods.
Does this study apply to women shift workers too?
This study only included male workers in Iran, so we don’t know if women have the same eating patterns. More research is needed to understand how shift work affects women’s diets and whether the findings apply to other countries.
Can shift work cause weight gain through unhealthy eating?
This study shows shift workers eat less healthily, which could contribute to weight gain, but it didn’t measure actual weight changes. The combination of unhealthy eating plus shift work’s effects on sleep and metabolism may increase weight gain risk.
Want to Apply This Research?
- Log your daily soft drink and processed snack intake for one week to establish a baseline, then set a goal to reduce soft drinks by 10% each week and track progress. Measure in grams or ounces to match the study’s findings
- Use the app to plan your meals for the week before your shift schedule begins. Set reminders to eat at consistent times even when your work schedule changes, and log healthy snacks you bring to work to replace vending machine options
- Track weekly averages of processed food intake, soft drink consumption, and meal frequency patterns. Compare your patterns across different work schedules (if applicable) to identify which shifts make healthy eating most challenging, then develop targeted strategies for those periods
This research shows an association between shift work and unhealthy eating patterns but does not prove that shift work causes poor eating habits. Individual results vary based on personal circumstances, food availability, and cultural factors. If you work shifts and have concerns about your diet or health, consult with a healthcare provider or registered dietitian for personalized advice. This article is for informational purposes and should not replace professional medical or nutritional guidance.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.