A new study provides the best evidence to date that eating fast food makes you fat. Among nearly 3,400 young adults participating in a long-term study, every additional fast food meal they consumed each week correlated with a substantial increase in body mass index (BMI), Dr Barry M. Popkin of the University of North Carolina in Chapel Hill and colleagues found.
"It's a large effect," Popkin told Reuters Health in an interview. "That's enough of an effect to take you from being non-diabetic to diabetic."
Food eaten away from home now accounts for up to 42 per cent of Americans' calorie intake, Popkin and his team note in their report in the American Journal of Clinical Nutrition. While the increase in restaurant and fast food consumption has occurred at the same time as the rise in obesity, they add, it's not clear if it's a contributing factor.
The more fast food the subjects ate, the higher was their BMI, Popkin and colleagues found. However, the researchers found no association between meals eaten at traditional restaurants and increases in BMI; in fact, some analyses linked eating more often in restaurants to a slightly lower BMI.
The study confirms, Popkin said, that people who eat more fast food pack on more pounds. "People have been trying to say that, but they didn't have the kind of evidence that we have now."