I have personally found this to be true and I’m surprised that they needed a study to determines this because I figured it out (and I didn’t even have a research grant :-):

Women who put on extra pounds raise their risk of getting frequent heartburn or making symptoms worse Â? even if they aren’t overweight, a new study found.
Compared to women whose weight didn’t change, a moderate gain doubled the chances of heartburn and acid reflux. Shedding the pounds cut the risk by about 40 percent, according to the report in Thursday’s New England Journal of Medicine.
[…]
Hagerty’s doctor at Boston University Medical Center said heartburn medicine is usually the first to go when patients drop weight and their symptoms ease.
“It’s as little as 10 pounds. It’s amazing,” said Dr. Caroline Apovian, director of the Center for Nutrition and Weight Management.

The news article didn’t mention it but I bet age has something to do with it as well. I didn’t have this problem a few years ago. And eating before bed or overeating means I will suffer from it in the middle of the night and it is not fun. I need to stick to my diet (but ice cream taste soooo good).