Not entirely, but the two things are certainly related. Many poor neighborhoods are "food deserts" with no significant grocery stores from which to buy ingredients. The poor are often left with fast food places and, if they are lucky, a bodega or other small establishment that does the best it can but does not have room for everything needed to cook a decent meal.
What they get includes excessive sodium, saturated fat, and far too many carbohydrates relative to the fruits, vegetables, and protein they need. This causes hypertension and excessive fat storage around the waistline. So: is this unique to poor neighborhoods? Yes and no.
Middle and upper-class people aren't immune from bad eating habits, of course. Advertisers see to that! However, they can find well-stocked stores near enough, or at least can afford to drive to them, and can even hire nutritionists or trainers to help them eat better and work out -- if they choose. They may, if they are in the limelight, feel more societal pressure to stay attractive for the camera. Of course, if they fail, they can also afford plastic surgery, liposuction and such. In other words, even their failures are lessened by socioeconomic factors.