Major causes of belly fat are genetics, improper digestion, stress, menopause, slow metabolism, lack of exercise and excess eating.

Stress: According to researches, belly fat can result from stress. When you are under stress, the cortisol hormone is released. Cortisol stimulates the fat storage around the belly. When you are stressed, you often feel hungry and tend to eat more, which can lead to excess weight gain.

Genetics: There are two body types such as apple body and pear body shapes. In case of pear-shaped body, fat accumulation is in the lower parts of the body. Fat stored in the abdomen and middle portion causes apple-shaped body. Most people have apple-shaped body. If any of your parents have such body type, then you are at a higher risk of developing belly fat.

Slow Metabolism: Metabolism rate is a major contributing factor in abdominal fat. A slower metabolism causes less burning of calories and excess accumulation of fats. You can increase the basal metabolic rate (BMR) with the help of a nutritious and balanced diet and regular exercises.

Improper Digestion: Over eating and improper digestion can lead to a number of gastrointestinal problems. It causes gases and bloating. Eating late at night can also interfere with proper digestion of food. Going to bed immediately after meals also increases the risk of fat storage around the abdominal area.

Lack Of Exercises: If you follow a lazy lifestyle and keep on eating without any physical activity, then it can lead to obesity and accumulation of belly fat. It is very essential to burn calories through exercises to maintain a healthy body weight.

Poor Posture: Poor body posture can leave you with a paunch or 'pot belly' appearance. The proper posture makes a great difference in your appearance.

Alcoholism: Alcohol decreases the rate of metabolism and increases obesity. Calories obtained from excess alcoholism are often stored around the abdominal area.

Menopause: Menopause is one of the main reasons for belly fat in women. After menopause, many women tend to accumulate fat around the tummy due to hormonal changes.

Source: buzzle.com/articles/what-causes-belly-fat.html