Following are the 12 things that may increase your belly fat:

Sugary foods and beverages
Processed food
Physical inactivity
Lack of sleep
Stress or cortisol
Smoking
Alcohol
Overeating
Bloating
Genetics
Low-protein diet
Menopause

There are few other factors such as a low-fiber diet, wrong gut bacteria, or aging that may make it easy for you to gain belly fat.

Fat surrounding the liver and other organs in the abdomen is known as visceral fat. Gaining belly fat is the biggest concern among all populations. Larger waistlines not only look unappealing but also cause health concerns such as heart disease, diabetes, and cancer. It can also affect the blood vessels and quality of the sleep. 

Here’s how these 12 things make you gain belly fat:

Sugary foods and beverages: Candies, cakes, frozen yogurt, soda, flavored coffee drinks, and sweet tea are generally considered to have high added sugars. These added sugars contain high fructose content. Studies have shown that a high fructose content might reduce the metabolic rate and fat burning. Hence, consuming more of added sugars will likely make you gain belly fat.
Processed food: Fibers, vitamins, and nutrients are ripped off from these foods. Processed foods such as white rice, white bread, and food products made of refined flour are easily digestible and lead to a rapid increase in blood sugar and insulin levels after meals. These foods also have a high content of salts and preservatives. 
Physical inactivity: Sedentary lifestyle remains the main culprit in increasing abdominal obesity. Women sitting continuously for more than three hours are at an increased risk of abdominal obesity.
Lack of sleep: Sleeping for less than five hours may result in a weight gain of around 32 lbs. Similarly, sleeping for more than eight hours also does the same. People with sleeping disorders are most likely to experience weight gain. Hence, sleeping for six to eight hours seems to be adequate and is essential.
Stress or cortisol: Stressing out a lot releases the “stress hormone” cortisol, which can increase abdominal obesity. Stress also leads to declined sleep quality, overeating, and heavy alcohol drinking, which in turn also contribute to abdominal obesity.
Smoking: Smokers generally have larger waistlines because smoking localizes the fat in the abdomen. Smoking can also cause diabetes, cancer, and heart diseases.
Alcohol: Alcohol is empty calories that may pile up around the tummy. Although alcohol in moderation can curtail the risk of heart attack and strokes, higher amounts of it may lead to inflammation, liver diseases, and other health issues. Some studies have shown that alcohol curbs fat burning, and as a result, the excess fat gets deposited in the abdomen.
Overeating: Most of the time, we tend to binge due to stress. Overeating can result in the consumption of excess calories and eventually weight gain. Thus, mindful eating is the key to prevent abdominal bulge.
Bloating: Bloating may not be permanent. It is the collection of gas in the gut and stomach and results in a feeling of fullness and tightness. Massaging can relieve bloating and prevent gas formation. Practices such as eating slowly, taking small morsels of food, and taking fennel after food can reduce bloating.
Genetics: Genetics can be a problem too while considering abdominal obesity. The tendency to store fats can be blamed upon genetics. Specific genes that regulate calorie intake and weight are found to be the culprit in gaining belly fat. Genetics leaves you with fewer options for repair.
Low-protein diets: Protein helps to build muscle mass. This helps in an increased metabolic rate and a decreased calorie intake. High-protein diets prevent weight gain and abdominal obesity.
Menopause: Menopause leads to a drop in the estrogen level leading to fat deposition in the abdomen rather than the thighs and hips.