The main reason behind this is the lack of physical activity. Daily exercise will help regulate your blood sugar levels. You must also try to reduce your meal size as well. If you consume more calories than you burn, excessive fat will develop in your stomach and upper back. Another helpful tip is to get a sufficient amount of sleep. Lack of sleep can cause changes in your hormones which can increase your appetite. An increased appetite can lead to weight gain, which can lead to fat being stored in your belly and back.