Of course eating meals prepared at home is healthier! The study results - that people who often consume meals prepared at home are less likely to suffer from type 2 diabetes than those who consume such meals less frequently shouldn't be surprising. The researchers attributed the higher incidence of type 2 diabetes to weight gain in those eating fewer meals prepared at home, but there are other things going on also.
Restaurant and fast food meals tend to have very large portions, frequently with rich sauces, and the meal choices tend to be heavy on fat and salt. The meals can be high in calories, contain many artificial ingredients, and may be low in nutritional quality (and so also not nourishing the beneficial gut microbes that are linked to health). At home you can limit portions, control the food ingredients, and eat only healthy foods (see earlier post on this). From Science Daily:
People who often consume meals prepared at home are less likely to suffer from type 2 diabetes than those who consume such meals less frequently, according to new epidemiological research reported by Qi Sun, of the Harvard T.H. Chan School of Public Heath, Boston, USA and colleagues as part of PLOS Medicine's special issue on Preventing Diabetes.
Internationally, there is an increasing tendency for people to eat out, and this could involve consumption of fast food, for example. Concerns have been raised that such people have a diet that is rich in energy but relatively poor in nutrients -- this could lead to weight gain which is, in turn, associated with an increased risk of type 2 diabetes.
Sun and colleagues employed large prospective data sets in which US health professionals -- both men and women--were followed-up for long periods, with rigorous collection of data on health indicators, including self-reported information on eating habits and occurrence of diabetes. The results were corrected for various known factors that could affect dining habits, including marital status. All in all, the study analyzed 2.1 million years of follow-up data.
The findings indicate that people who reported consuming 5-7 evening meals prepared at home during a week had a 15% lower risk of type 2 diabetes than those who consumed 2 such meals or fewer in a week. A smaller, but still statistically significant, reduction was apparent for those who reported consuming more midday meals prepared at home. Other analyses suggest that less weight gain could partially explain the reported reduction in occurrence of type 2 diabetes in those often eating meals prepared at home.