Friday August 8 2014
People who dine out 'consume more calories'
"Eating in restaurants no better than fast food for health," reports The Daily Telegraph after the publication of a study on the calorie intake of eating out.
The US study found people who enjoyed dining at a full-service restaurant consumed just as many calories as those who ate fast food.
Researchers looked at the diets of more than 12,500 Americans and found those who dined out at non-fast-food restaurants ate 205 calories more than those who ate at home. Those eating out at fast-food restaurants were not far behind, at 194 extra calories.
In an interview with The Daily Telegraph, lead study author Dr Binh Nguyen suggested restaurant food was higher in calories than home-cooked food because "they have more energy-dense foods and bigger portions".
However, this seems speculative as the study didn't report portion size, making it difficult to know what diners were eating and in what quantity. This missing piece of information is important as it has the potential to significantly influence the study's findings.
In the UK, the average person eats one in every six meals outside the home and we consume up to a quarter of our calories when eating out, according to the Food Standards Agency.
Eating out has been linked to a higher risk of being overweight or obese, which increases the risk of weight-related diseases such as cardiovascular disease and diabetes.
For those who want to maintain a healthy weight, being aware of different sources of energy from food and drink may help you achieve your weight-related goals.
This includes awareness of the possible impact of eating away from the home often, where a person has less direct control over their calorie consumption compared with a home-cooked meal.
For more help and advice on healthy living, check out the NHS Choices healthy eating section.
Where did the story come from?
The study was carried out by researchers from the American Cancer Society and the School of Public Health at the University of Illinois, and was funded by the US National Heart, Lung and Blood Institute.
It was published in the peer-reviewed journal, Public Health Nutrition.
The media generally reported the story accurately, although few explored the potential limitations of the study.
What kind of research was this?
This was a cross-sectional analysis of data collected from a large US cohort study looking at whether eating away from the home influenced the number of calories people consumed in a day.
The research authors highlight that, in line with rising rates of obesity in the US, there has been a marked upward trend in total energy intake derived from food consumed away from home.
Given the large and increasing numbers of people eating away from home, the researchers wanted to assess the effect of fast-food and full-service restaurant consumption on adults' energy intake and dietary indicators.
What did the research involve?
The study recruited non-pregnant adults aged from 20 to 64 who were taking part in a large US nationally representative study called the National Health and Nutrition Examination Survey between 2003 and 2010.
Participants completed two dietary interviews on non-consecutive days, where they reported all foods and beverages consumed in the previous 24 hours. Based on this information, calorie consumption – a measure of the energy content of food and drink – was estimated.
The survey participants were also asked about the source of each food and beverage item in terms of where it came from – for example, from a shop, fast-food restaurant or full-service restaurant.
The full sample included 12,528 people, who completed dietary recall interviews on both days. Those with missing data were excluded from the results.
The main analysis compared the calorie intake of people who reported eating out at fast-food restaurants or full-service restaurants with those who reported eating at home. They also analysed sugar, salt and fat intake.
What were the basic results?
The main result was that eating at fast-food and full-service restaurants was associated with consuming more calories.
Fast-food and full-service restaurant consumption was associated with an increase in daily total energy intake of 194kcal and 205kcal respectively, and higher intake of saturated fat (3.48g and 2.52g) and salt (296.38mg and 451.06mg).
Black adults consumed more calories from eating out compared with their white and Hispanic counterparts, the study found. The same was true for middle-income compared with high-income adults.
How did the researchers interpret the results?
The study authors found that "adults' fast-food and full-service restaurant consumption was associated with higher daily total energy intake and poorer dietary indicators".
They observed that people did not compensate for this calorie surplus by reducing their energy intake over the rest of the day, which meant their overall calorie intake was higher on days when they ate out.
This large study of US adults suggests people eating away from home consume around 200 extra calories compared with people eating at home in any single day. The added calories associated with eating out were similar, regardless of whether people went to a full-service restaurant or a fast-food restaurant.
While the broad conclusions of the study are perfectly plausible, there are a number of limitations to be aware of.
The information on diet came from asking people to recall what they ate in the previous 24 hours, which might be prone to error. People can over or underestimate their food intake and portion size, which would influence the calorie consumption calculation and potentially bias the results.
The analysis did not take into account physical activity levels, so in theory people may have been able to burn off some of the added calories associated with eating out. Related to this, people may eat more after being physically active because of an increase in appetite.
The point is that calories consumed are only one side of the weight equation, the other side being calories burned. We therefore cannot tell whether these added calories actually contributed to long-term weight gain or an increase in disease risk.
The study did not report what the people ate or their portion size, as they were eating outside the home. There was also not enough information to glean details about what types of restaurant food might be better or worse for adding calories.
The study was based in the US, and although the UK diet is similar, there may be important differences in terms of the type of restaurant food and portion size, which means the study's results are less applicable to people in the UK.
However, we should not be complacent as many trends and findings in the US are applicable to the UK in many ways.
Overall, this study serves to remind anyone conscious of their weight to be aware of the potential effects of eating out regularly.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.