Young adults who eat frequently at fast-food restaurants gain more weight and have a greater increase in insulin resistance in early middle age, according to a large multi-center study published in the January 1 issue of The Lancet.
After 15 years, those who ate at fast-food restaurants more than twice each week compared to less than once a week had gained an extra ten pounds and had a two-fold greater increase in insulin resistance, a risk factor for type 2 diabetes. Diabetes is a major risk factor for heart disease.
Obesity and diabetes are on the rise around the world and the study highlights the value of healthy eating habits.
"It's extremely difficult to eat in a healthy way at a fast-food restaurant. Despite some of their recent healthful offerings, the menus still tend to include foods high in fat, sugar and calories and low in fibre and nutrients," said lead author Mark Pereira, assistant professor of epidemiology at the University of Minnesota.
People need to evaluate how often they eat meals at fast-food restaurants and think about cutting back, according to Pereira.
One reason for the weight gain may be that a single meal from one of these restaurants often contains enough calories to satisfy a person's caloric requirement for an entire day.
Participants were asked during the physical examinations given as part of the study how often they ate breakfast, lunch or dinner at fast-food restaurants. Researchers found that the adverse impact on participants' weight and insulin resistance was seen in both blacks and whites who ate frequently at fast-food restaurants, even after adjustment for other lifestyle habits.
Study participants included 3,031 young black and white adults who were between the ages of 18 and 30 in 1985-1986. The participants, who were part of the Coronary Artery Risk Development in Young Adults (CARDIA) study, received dietary assessments over a 15-year period.
According to the study, men visited fast-food restaurants more frequently than women and blacks more frequently than whites. Black men reported an average frequency of 2.3 visits per week in 2000-01. White women had the lowest frequency, at an average of 1.3 visits per week in 2000-01.