While it may seem obvious, we now have research showing a positive link between eating fast food, weight gain and diabetes. Up to this point there have been no long-term studies documenting the effect of fast food on obesity, type 2 diabetes and heart disease.

Data from a cardiac health study involving 3000 young people was used to determine if there is a link between eating fast food, weight gain and diabetes. Subjects in the 15-year study received a medical checkup and answered questions about diet, physical activity and other lifestyle factors.

After controlling for other factors, researchers determined that eating fast food twice a week or more was associated with a weight gain of 10 pounds over the course of the study. Fast food eaters had more than double the chance of developing insulin resistance, which is a predictor of type 2 diabetes and is also strongly linked to obesity.

Reference
Pereira, Mark A. et al. Fast-food habits, weight gain, and insulin resistance (the CARDIA study): 15-year prospective analysis. Lancet. 2005; 365: 36-42