Back far is commonly caused by atrophy of the back on top of excess body fat. Atrophy of the back means that the muscles have lost their tone and strength resulting in those stubborn back rolls. Additionally, your exercise regiment is a contributing factors. Minimal physical activity can result in a slower metabolism which can cause you to gain weight in multiple areas, including your back. Your diet can also cause excess back fat if you tend to eat products that are high in calories, fat, carbohydrates, sugar, and sodium. These ingredients are known to cause weight gain.