From The Atlantic: Are prepared foods making us fat?
It is a topic I am pursuing, and I continue to be surprised at the dearth of studies. Barbara Rolls and colleagues have shown that portion size influences caloric intake; because prepared foods are often served in large portions, it seems likely that they promote excessive caloric intake and weight gain. But we need more research to make the connection between prepared foods and weight gain.
Further complicating the picture is the huge number of foods that fall under the term “prepared” or “semi-prepared”–and because people are cooking less and less, their very idea of what a prepared food is may be changing. Putting pasta sauce from a jar on cooked spaghetti may or may not be considered using prepared foods, depending on the perspective of the “cook.”
Further complicating things is the many foods like macaroni and cheese that can be made at home either from scratch or from a mix–or bought as a ready-to-eat dish. Unfortunately, most epidemiologic studies that follow people’s diets and weights over time don’t collect the details that would allow the authors to differentiate between what was made from scratch and foods at least semi-prepared outside the home. This may explain why there is so little research on the association between prepared foods and obesity.