Many people eat not when they are hungry or have appetite but also for a reason of participation in social occasions or celebration of big events. But when they consume too much food, they get excessive amount of calories. As a result, fat is accumulated in their bodies. If a person continues to overeat, he or she may become morbidly obese. Obesity is a medical condition that results in immoderate body fat to an extent that it may affect person’s health. This may lead not only to different diseases but may considerably reduce a person’s life span. The majority of people are aware about negative effects of overeating. However, they are often reluctant to give up their unhealthy habit. What does prevent them from doing so? Is it not better to go back to a healthy lifestyle and to enjoy its benefits? To answer this question, it is important to understand what drives people to eat. There are three major factors that influence people’s eating behavior – psychological, biological and cultural. To find the roots of overeating and treat the obesity, it is necessary to research these areas of a person’s life. Current essay will focus on these three factors and their role in overeating and obesity. Psychological Factors of Eating Disorder Psychological factors, perhaps, the most frequently affect people and cause them to consume more food than they really need. For example, depression and eating disorder are often linked together. A person may gain weight due to psychological shifts in his or her hormone and immune system. Also, when depression comes, it is more difficult to get a positive attitude and have an active lifestyle. In this case, a person may not be inclined to physical exercises or going outside. At the same time, those who are overweight have tendency to be depressed, as they often realize their poor health and unsatisfactory appearance. Especially, this is a case with women and people of high social status. Some people struggle to control their impulses. As soon as they see tasty food, they cannot resist temptation – they eat by impulse. Such people often have difficulties to stop in time, and thus overeat. Apparently, people who have this type of impulse disorder need to learn how to manage and express their feelings. Children who suffer from obesity often have a low self-esteem. As a result, they may experience sadness and loneliness which often cause depression. Suffering abuse or neglect, especially, in childhood may also lead to obesity. As food seems to temporarily relieve past pain, people with trauma have a tendency to eat something very frequently. In the same manner, many people try to relieve their stress, but in those who had trauma this mechanism is amplified. Biological Factors of Eating Disorder Biological factors may also contribute to overeating. For example, if hypothalamus (a part of brain responsible for appetite) dysfunctions sending incorrect messages concerning appetite a person will be ‘deceived’ and eat more than he or she actually needs. Since hypothalamus cannot sense the response from the fat that gives a command to put off hunger, a person thinks he/ she still wants to eat. Though the consumed calories are stored, the person does not feel full. As a result, the gain of weight may reach about 2 pounds a week. The fat is usually stored in muscles and in organs in the belly, particularly in liver. Under such circumstances, the organs have difficulty to function properly. Low level of serotonin is another biological force that may cause obesity. When serotonin level is low, human body senses a false need in carbohydrates. It is well- known that carbohydrates contribute to fat formation. This may lead to obesity. Recently, the researchers discovered genetic mutation that may cause an eating disorder. The mutation affects MTHFR gene which is responsible for homocysteine metabolism. Mutations of the MTHFR gene may cause elevated blood levels of homocysteine. This factor is recognized as a high risk factor of various medical conditions including obesity. Another substance that may influence app?tit is leptin. This is a hormone that is produced from fat tissue and it functions as an inhibitor of appetite. However, in the modern time humans do not have the problems with food supply anymore. At the same time, the desire to eat this kind of food is still preserved. Cultural Factors of Eating Disorders Each culture has different eating habits. Some of them may be healthy but others may lead to obesity depending on food value. Cuisine where vegetables and fruits dominate will shape healthier people. If a cultural menu is abundant with greasy food, it is likely that the representatives of that culture will have tendency to obesity. At the same time, there are cultures that encourage people to be thin and put shame to those who overeat. This practice of setting restrictions on eating may cause an opposite effect. People, while hiding their overeating habit, will develop even greater eating disorder. This is sometimes called emotional eating. In some families, however, children are encouraged to eat more. Parents use food to comfort their children or if they are very busy, food serves the purpose to dismiss the children. Using food for reward is also an option for some people. Children who are exposed to frequent critical comments about their bodies and weight are also vulnerable, as are those who have been sexually abused in childhood. To develop an eating disorder, it usually takes a combination of three major factors – psychological, biological and socio-cultural. This includes person’s emotional and socio-cultural experiences. Psychological trauma is a powerful force that may affect eating behavior of humans, as well as cultural practices. Also the function of hypothalamus is very important, as it has to provide proper signals from the fat tissues. The hormones, such as serotonin and leptin, play a vital role in controlling an appetite too. Therefore, while dealing with the problem of eating disorder or obesity it is necessary to consider all the factors discussed above.