Scientifically, obesity occurs from consuming more calories than needed by the body. Cause of the imbalance between calorie intake and burning is still unclear.
The occurrence of obesity involves several factors:
Genetic factors. Obesity tends lowered, so suspected to have genetic causes. But family members not only share genes but also diet and lifestyle habits, which can promote obesity. Often difficult to separate the lifestyle factors with genetic factors. Recent research shows that the average genetic factors influence 33% of the weight.
Environmental factors. Gene is an important factor in many cases of obesity, but one's environment also plays a significant role. This environment includes behavioral / lifestyle patterns (eg what to eat and how many times someone eat and how their activities). A person certainly can not change their genetic pattern, but he can change the diet and activity.
Psychological factors. What's in a person's mind can affect her eating habits. Many people reacted to his emotions by eating.
One form of emotional disturbance is a negative self-perception. This disorder is a serious problem in many young women who suffer from obesity, and can cause excessive awareness about obesity and discomfort in social interaction.
There are two abnormal eating patterns that could be the cause of obesity is eating in a number of very much (binge) and eat at night (at night eating syndrome). Both diets are usually triggered by stress and disappointment. Binge similar to bulimia nervosa, in which a person eat in a number of very many, the difference in binge this is not followed by the brings back what has been eaten. As a result, the calories consumed very much. On the night eating syndrome, is a reduced appetite in the morning and followed by excessive eating, agitation and insomnia at night.
Health factors. Some diseases can cause obesity, including:
Hypothyroidism
Cushing's syndrome
Prader-Willi Syndrome
Some nerve disorders that can cause a person to eat a lot.
Drugs.
Certain medications (eg steroids and some anti-depressants) can cause weight gain.
Growth factor. The addition of size or number of fat cells (or both) cause increasing amounts of fat stored in the body. Obese people, especially those being fat in childhood, can have the fat cells to 5 times more than people whose weight is normal. The number of fat cells can not be reduced, because the weight loss can only be accomplished by reducing the amount of fat in each cell.
Physical activity. Lack of physical activity is probably one of the main causes of the increasing incidence of obesity in the middle of a prosperous society. People who are inactive need fewer calories. Someone who tend to consume foods rich in fat and not a balanced physical activity, will be obese.