Over consumption of fast foods, processed meats, high fat and sugar drinks and desserts , and fried foods and just too much carbs are  causing this epidemic.  It all comes down to
what you put in your pie hole and that is 90% if not more as to  whether you are setting yourself up
for a chronic illness like diabetics, kidney disease, heart disease, and cancers of all kinds and obesity.  Exercise is important also but it plays only a very small part.