I've NOTICED a huge difference (pun intended) in the past ten years. Part of it is more people have cars and motos, but also way more fast-food is available. My brother-in-law sells all that crap that makes you fat at his student cafeteria, and he only sells what they want. The amount of children that bring a healthy lunch and snacks to school out of 600 children you can count on your fingers.
At the new school with the little ones we are trying to change that by selling no candy, but it's a hard habit to break when these kids are practically born with a sucker in their mouths.
Lots of Dominican kids are involved in sports, and even most of fat ones play baseball, but a steady diet of starches, sugars, and processed junk food will get you fat in a hurry.