A major new international study has found that eating meals prepared outside the home is strongly linked to weight gain and obesity across the world.
The findings suggest that restaurants, fast-food chains, takeaway meals, and other commercially prepared foods may be playing a much larger role in the global obesity crisis than many people realize.
The research was presented at the European Congress on Obesity (ECO 2026) in Istanbul, Turkey, and was led by scientists from Göttingen University and Heidelberg University in Germany.
The study looked at data from 65 countries and included more than 280,000 adults between 2009 and 2021. The researchers wanted to better understand how often people eat food prepared away from home and how this may affect body weight.
For years, scientists have warned that obesity rates are increasing rapidly around the world. Obesity is now considered one of the biggest public health problems because it raises the risk of heart disease, diabetes, high blood pressure, stroke, cancer, joint problems, and many other illnesses.
While unhealthy diets and lack of exercise are well-known causes, this new study highlights the growing importance of eating outside the home.
Food prepared away from home often contains larger portions, more calories, and higher amounts of salt, sugar, and unhealthy fats compared to home-cooked meals. Many commercial foods are also heavily processed, which can make people eat more without realizing it.
Previous studies had already shown a connection between eating out and obesity in wealthy countries like the United States and parts of Europe. However, much less was known about lower-income countries, where lifestyles and food systems are changing very quickly.
To fill this gap, the researchers analyzed large national health surveys from low-income, middle-income, and high-income countries. Participants answered questions about how many meals they ate outside the home each week, including breakfast, lunch, and dinner.
The results showed that almost half of adults worldwide eat meals prepared away from home at least once every week. However, eating habits varied greatly between regions.
In the Americas, about 81% of adults reported eating out at least once a week. In South East Asia, the number was much lower at around 26%. In central Europe, about 36% of adults said they regularly ate meals prepared outside the home.
Not surprisingly, people in wealthier countries generally ate out much more often. Adults in high-income countries consumed more than three times as many outside meals compared to adults in low-income countries.
But the study also found something very important. In low-income and lower-middle-income countries, people who were overweight or obese were much more likely to eat out frequently.
For example, adults with obesity in low-income countries had 39% higher rates of eating outside the home compared to adults with normal body weight. In lower-middle-income countries, people living with obesity had 20% higher levels of outside meal consumption.
The researchers believe this may reflect what scientists call a “nutrition transition.” As countries become wealthier and cities grow larger, fast food and commercially prepared meals become more available and affordable. Traditional home cooking may slowly decline while highly processed foods become more common.
The study also found several social patterns linked to eating out. Men tended to eat outside the home more often than women. Younger adults ate out more frequently than older adults. People who were unmarried, employed, or highly educated also tended to consume more outside meals.
According to the researchers, eating out may represent social status and wealth in poorer countries, while in richer countries it has become a normal part of daily life.
The findings are important because they suggest obesity prevention should not focus only on personal choices at home. Public health experts may also need to pay closer attention to restaurants, takeaway food, and the wider food environment.
Professor Sebastian Vollmer, one of the senior researchers, explained that modern food environments make it difficult for people to avoid overeating. Large portion sizes, processed foods, sugary drinks, and aggressive food marketing all encourage people to consume more calories than they need.
The researchers believe governments and health organizations may need stronger policies to improve the nutritional quality of food sold outside the home. This could include clearer food labels, healthier restaurant menus, smaller portion sizes, and limits on unhealthy food advertising.
Still, the study has some limitations. Because the research only observed patterns in people’s eating habits, it cannot prove that eating out directly causes obesity. Other lifestyle factors, such as physical activity, exercise habits, and overall calorie intake, may also influence body weight.
The researchers also relied on self-reported surveys, which means some people may not have remembered their meals accurately. In addition, the surveys counted the number of meals eaten outside the home but did not fully measure the nutritional quality of the food.
Even with these limitations, the study provides strong evidence that eating meals prepared outside the home is closely linked to obesity worldwide.
Overall, the findings suggest that the global obesity crisis is not simply about individual willpower. The modern food environment itself may be making healthy choices harder for millions of people.
As eating out becomes more common across the world, scientists say finding ways to make outside food healthier could become one of the most important steps in fighting obesity.
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Source: Göttingen University and Heidelberg University.
