The obesity epidemic has helped focus attention on Americans' eating habits, with an eye to the extent to which they are associated with consumption of excess calories. In addition, understanding these habits may lead to means of improving diet quality. In the interests of both these aims, researchers from the University of Washington in Seattle, led by Dr. Adam Drewnowski (an ACSH scientific advisor) queried 437 consumers on what and where they ate. In particular, the investigators were interested in following up on previous studies suggesting that meals consumed at home were of higher quality than those eaten outside the home. Their study appears in the American Journal of Preventive Medicine.
The participants in the study were the primary food shoppers for their families, were 21-55 years old, and 70 percent were women. They reported on the weekly frequency of cooking dinner at home versus frequency of eating out, completed food frequency questionnaires, and provided information on socioeconomic characteristics.
Reported food intakes were then compared to the USDA's Healthy Eating Index (HEI)(1) to assess the quality of participants' diets. The investigators found that people who cooked at home 6 or more times per week had significantly higher HEI scores than those who only cooked at home no more than three times per week. Conversely, those who ate outside more than three times per week had significantly lower HEI scores (and these eating sessions included all types of restaurants). Other characteristics that were also significantly associated with more frequent at-home meals were: being married; having children in the household; having 2-6 people in the home and being employed. Interestingly, the frequency of home-consumed meals was not associated with income level, or with greater food expenditures. This latter observation is particularly interesting since it has been observed that foods considered most healthful tend to be more expensive (e.g., fresh fruits and vegetables vs. processed varieties).
Taken as a whole, these authors suggest "Cooking dinners at home may be an effective strategy to reduce the consumption of empty calories, and improve diet quality within the budget" and they also suggest that efforts should be made to target such meals as a strategy to improve Americans' diet quality.
It's important to note that this was a cross-sectional study (only one point in time) rather than a longitudinal study that might look at impacts on health of the different dietary habits. And of course, the data were all self-reported, which can lead to bias. While one can not make causal inferences from this study, it is in line with previous research, according to the authors, and is an important aspect of American's food-related behavior.
1) The Healthy Eating Index or HEI. The Healthy Eating Index (HEI) is a measure of diet quality that assesses conformance to the Dietary Guidelines for Americans. It uses data from 24-hour dietary recalls during national surveys (such as NHANES) as the basis for assessing compliance. The compliance scores range from 0 to 100, with higher numbers being better.