But there are many factors, which can increase your risk of weight gain & obesity. You can not change or modify some of the risk factors like genetics, but there are some risk factors that you can change. Risk factors for obesity are:

High calorie diet:

Consumption of too many calories or high calorie foods and not getting enough physical activity to burn those calories results in weight gain & obesity.

1 gm of carbohydrate provides 4 calories, 1 gm of protein - 4 calories and 1 gm of fat - 9 calories. So, foods with high fat content are rich in calories. Also, foods & beverages like soft drink, desserts, which are high in sugar can also lead to weight gain.

Physical inactivity:

Your body weight is mainly determined by the balance between your calorie intakes from food with the calories you burn in daily activities. Inactivity or sedentary lifestyle is a major risk factor for obesity because extra calories, which are not used in physical activities, are deposited in body as fat.

Psychological & emotional factors:

Psychological factors can change eating habits. Some people overeat to deal with emotions like stress, boredom, anger & sadness.

Genetics factors:

Sometimes, obesity runs in families & if your parents are obese, your chances of being overweight are also high.

Age:

Incidence of obesity increases with increase in age. As physical activity level decreases with age, if caloric intake is not adjusted then extra calories will be deposited as fat.

Cigarette smoking:

Nicotine from cigarette increases metabolic rate of your body. High metabolic rate means more burning of calories by the body. When you quit smoking, you may gain weight temporarily.

However, cigarette smoking is associated with lot of health problems and benefits of stopping cigarettes exceed the risk of temporary gain in weight. You can avoid this weight gain by increasing physical activity & reducing calorie intake.

Drugs:

Certain medications like corticosteroids, tricyclic antidepressants, antipsychotic medications can increase your risk of being obese

Diseases or medical conditions:

Obesity is associated with certain medical conditions like hypothyroidism (low thyroid function), Cushing's syndrome (excess hormone production by adrenal gland), arthritis (due to decrease physical activity).

Alcohol:

Alcohol contains calories & it also increases appetite. So, drinking alcohol can lead to weight gain due to the caloric content of the alcohol as well as its appetite-enhancing effects.

So, you can control your weight by changing modifiable risk factors like high calorie diet, physical inactivity, and sedentary lifestyle & avoid complications of obesity.

You can get details on complications of obesity at